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877 results on '"Koop, I."'

1. Measurement of the $e^+e^-\to K_SK_L$ cross section near the $\phi(1020)$ resonance with the SND detector

Author

SND Collaboration, Achasov, M. N., Barnyakov, A. Yu., Bedarev, E. V., Beloborodov, K. I., Berdyugin, A. V., Bogdanchikov, A. G., Botov, A. A., Chistyakov, D. E., Dimova, T. V., Druzhinin, V. P., Kardapoltsev, E. V., Kasaev, A. S., Kattsin, A. A., Kharlamov, A. G., Koop, I. A., Korol, A. A., Kovrizhin, D. P., Kupich, A. S., Kryukov, A. P., Melnikova, N. A., Muchnoi, N. Yu., Obrazovsky, A. E., Pakhtusova, E. V., Pugachev, K. V., Rastigeev, S. A., Rogovsky, Yu. A., Senchenko, A. I., Serednyakov, S. I., Shatunov, Yu. M., Sherstyuk, S. P., Shtol, D. A., Silagadze, Z. K., Surin, I. K., Usov, Yu. V., Zhabin, V. N., and Zharinov, Yu. M.

Subjects
High Energy Physics - Experiment
Abstract

The cross section for the $e^+e^-\to K_SK_L$ process is measured in the center-of-mass energy range from 1000 MeV to 1100 MeV in the experiment with the SND detector at the VEPP-2000 $e^+e^-$ collider. The measurement is carried out in the $K_S\to 2\pi^0$ decay mode. Data with an integrated luminosity of 20 pb$^{-1}$ recorded in 2018 at 18 energy points are used in the analysis. The systematic uncertainty in the measured cross section at the maximum of the $\phi$ resonance is 0.9%. The mass, width of the $\phi$ meson, and the product of the branching fractions $B(\phi\to K_SK_L)B(\phi\to e^+e^-)$ are determined from the fit to the cross-section energy dependence., Comment: 14 pages, 12 figures

Published
2024

2. Search for the process $\mathbf{\it e^+e^-\to\eta^{\prime}\gamma}$ in the energy range $\mathbf{\it \sqrt{s}}$ = 1.075 -- 2 GeV

Author

Achasov, M. N., Barnyakov, A. Yu., Bedarev, E. V., Beloborodov, K. I., Berdyugin, A. V., Bogdanchikov, A. G., Botov, A. A., Dimova, T. V., Druzhinin, V. P., Zhabin, V. N., Zharinov, Yu. M., Kardapoltsev, L. V., Kasaev, A. S., Kattsin, A. A., Kyrpotin, A. N., Kovrizhin, D. P., Koop, I. A., Korol, A. A., Kupich, A. S., Kryukov, A. P., Melnikova, N. A., Muchnoy, N. Yu., Obrazovsky, A. E., Pakhtusova, E. V., Pugachev, K. V., Rastigeev, S. A., Rogovsky, Yu. A., Senchenko, A. I., Serednyakov, S. I., Silagadze, Z. K., Surin, I. K., Usov, Yu. V., Kharlamov, A. G., Chistyakov, D. E., Shatunov, Yu. M., Sherstyuk, S. P., and Shtol, D. A.

Subjects
High Energy Physics - Experiment
Abstract

The results of the search for the $e^+e^-\to\eta^{\prime}\gamma$ process in the center-of-mass energy range from 1.075 to 2 GeV are presented. We analyze data with an integral luminosity of 746 pb$^{-1}$ accumulated with the SND detector at the $e^+e^-$ collider VEPP-2000 in 2010--2024. The $\eta^{\prime}\to\eta\pi^0\pi^0$ decay is used in the analysis, with the subsequent $\eta$ and $\pi^0$ decays into $\gamma\gamma$. Upper limits not exceeding 13 pb have been set on the $e^+e^-\to\eta^{\prime}\gamma$ cross section at the 90\% confidence level., Comment: 5 pages, 2 figures. arXiv admin note: text overlap with arXiv:2306.12734

Published
2024

3. Measurement of the pion form factor with CMD-3 detector and its implication to the hadronic contribution to muon (g-2)

Author

Collaboration, CMD-3, Ignatov, F. V., Akhmetshin, R. R., Amirkhanov, A. N., Anisenkov, A. V., Aulchenko, V. M., Bashtovoy, N. S., Berkaev, D. E., Bondar, A. E., Bragin, A. V., Eidelman, S. I., Epifanov, D. A., Epshteyn, L. B., Erofeev, A. L., Fedotovich, G. V., Gorkovenko, A. O., Grancagnolo, F. J., Grebenuk, A. A., Gribanov, S. S., Grigoriev, D. N., Ivanov, V. L., Karpov, S. V., Kasaev, A. S., Kazanin, V. F., Khazin, B. I., Kirpotin, A. N., Koop, I. A., Korobov, A. A., Kozyrev, A. N., Kozyrev, E. A., Krokovny, P. P., Kuzmenko, A. E., Kuzmin, A. S., Logashenko, I. B., Lukin, P. A., Lysenko, A. P., Mikhailov, K. Yu., Obraztsov, I. V., Okhapkin, V. S., Otboev, A. V., Perevedentsev, E. A., Pestov, Yu. N., Popov, A. S., Razuvaev, G. P., Rogovsky, Yu. A., Ruban, A. A., Ryskulov, N. M., Ryzhenenkov, A. E., Semenov, A. V., Senchenko, A. I., Shatunov, P. Yu., Shatunov, Yu. M., Shebalin, V. E., Shemyakin, D. N., Shwartz, B. A., Shwartz, D. B., Sibidanov, A. L., Solodov, E. P., Talyshev, A. A., Timoshenko, M. V., Titov, V. M., Tolmachev, S. S., Vorobiov, A. I., Yudin, Yu. V., Zemlyansky, I. M., Zhadan, D. S., Zharinov, Yu. M., and Zubakin, A. S.

Subjects
High Energy Physics - Experiment
Abstract

The cross section of the process $e^+e^-\to\pi^+\pi^-$ has been measured in the center-of-mass energy range from 0.32 to 1.2 GeV with the CMD-3 detector at the electron-positron collider VEPP-2000. The measurement is based on an integrated luminosity of about 88 pb$^{-1}$, of which 62 pb$^{-1}$ represent a complete dataset collected by CMD-3 at center-of-mass energies below 1 GeV. In the dominant region near the $\rho$ resonance a systematic uncertainty of 0.7% was achieved. The implications of the presented results for the evaluation of the hadronic contribution to the anomalous magnetic moment of the muon are discussed., Comment: 8 pages, 3 figures; as published in Phys. Rev. Lett. 132, 231903

Published
2023
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4. Measurement of the neutron timelike electromagnetic form factor with the SND detector

Author

SND Collaboration, Achasov, M. N., Barnyakov, A. Yu., Bedarev, E. V., Beloborodov, K. I., Berdyugin, A. V., Berkaev, D. E., Bogdanchikov, A. G., Botov, A. A., Dimova, T. V., Druzhinin, V. P., Zhabin, V. N., Zharinov, Yu. M., Kardapoltsev, E. V., Kasaev, A. S., Kovrizhin, D. P., Koop, I. A., Korol, A. A., Kupich, A. S., Kryukov, A. P., Lysenko, A. P., Melnikova, N. A., Muchnoy, N. Yu., Obrazovsky, A. E., Pakhtusova, E. V., Pugachev, K. V., Rastigeev, S. A., Rogovsky, Yu. A., Serednyakov, S. I., Silagadze, Z. K., Surin, I. K., Usov, Yu. V., Kharlamov, A. G., Shatunov, Yu. M., and Shtol, D. A.

Subjects
High Energy Physics - Experiment
Abstract

The results of the measurement of the $e^+e^- \to n \bar{n}$ cross section and effective neutron timelike form factor are presented. The data taking was carried out in 2020-2021 at the VEPP-2000 $e^+e^-$ collider in the center-of-mass energy range from 1891 to 2007 MeV. The general purpose nonmagnetic detector SND is used to detect neutron-antineutron events. The event selection is performed using the time-of-flight technique. The measured cross section is 0.4-0.6 nb. The neutron form factor in the energy range under study varies from 0.3 to 0.2., Comment: 13 pages, 8 figures

Published
2023

5. Study of the process $e^+e^- \to \omega\pi^0 \to \pi^+\pi^-\pi^0\pi^0$ in the energy range $1.05-2.00$ GeV with SND

Author

SND Collaboration, Achasov, M. N., Barnyakov, A. Yu., Beloborodov, K. I., Berdyugin, A. V., Berkaev, D. E., Bogdanchikov, A. G., Botov, A. A., Denisov, V. S., Dimova, T. V., Druzhinin, V. P., Eminov, E. A., Fomin, L. B., Kardapoltsev, L. V., Kharlamov, A. G., Koop, I. A., Korol, A. A., Kovrizhin, D. P., Kupich, A. S., Kryukov, A. P., Melnikova, N. A., Muchnoy, N. Yu., Obrazovsky, A. E., Pakhtusova, E. V., Perevedentsev, E. A., Pugachev, K. V., Rogovsky, Yu. A., Serednyakov, S. I., Shatunov, Yu. M., Shtol, D. A., Silagadze, Z. K., Surin, I. K., Timoshenko, M. V., Usov, Yu. V., Zemlyansky, I. M., Zhabin, V. N., and Zhulanov, V. V.

Subjects
High Energy Physics - Experiment
Abstract

The process $e^+e^- \to \omega\pi^0 \to \pi^+\pi^-\pi^0\pi^0$ is studied in the center-of-mass energy region $1.05-2.00$ GeV using data with an integral luminosity of about 35 pb$^{-1}$ collected with the SND detector at the VEPP-2000 $e^+e^-$ collider. In the energy range under study, the value of the measured Born cross section varies from 0.7 to 18 nb. The statistical uncertainty of the cross section is $2-23$%, while the systematic uncertainty is in the range of $3.0-14.2$%. The results are consistent with previous measurements but have better accuracy., Comment: 13 pages, 11 figures

Published
2023

8. Study of the process $e^+e^-\to\eta\gamma\to 7\gamma$ in the energy range $\sqrt{s}$ = 1.07 -- 2 GeV

Author

SND Collaboration, Achasov, M. N., Barnyakov, A. Yu., Beloborodov, K. I., Berdyugin, A. V., Bogdanchikov, A. G., Botov, A. A., Denisov, V. S., Dimova, T. V., Druzhinin, V. P., Fomin, L. B., Kharlamov, A. G., Kardapoltsev, L. V., Kyrpotin, A. N., Koop, I. A., Korol, A. A., Kovrizhin, D. P., Kryukov, A. P., Kupich, A. S., Melnikova, N. A., Muchnoi, N. Yu., Obrazovsky, A. E., Pakhtusova, E. V., Perevedentsev, E. A., Pugachev, K. V., Rogovsky, Yu. A., Serednyakov, S. I., Silagadze, Z. K., Surin, I. K., Timoshenko, M. V., Usov, Yu. V., Zhabin, V. N., Zhulanov, V. V., Zemlyansky, I. M., Shatunov, Yu. M., Shtol, D. A., Shukaev, A. N., and Eminov, E. A.

Subjects
High Energy Physics - Experiment
Abstract

The $e^+e^-\to\eta\gamma$ cross section is measured in the center-of-mass energy range from 1.07 to 2.00 GeV in the decay channel $\eta\to 3\pi^0$, $\pi^0\to\gamma\gamma$. The data set with an integrated luminosity of 242 pb$^{-1}$ accumulated in the experiment with the SND detector at the VEPP-2000 $e^+e^-$ collider is analyzed., Comment: 12 pages, 3 figures

Published
2023
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9. STCF Conceptual Design Report: Volume 1 -- Physics & Detector

Author

Achasov, M., Ai, X. C., Aliberti, R., An, L. P., An, Q., Bai, X. Z., Bai, Y., Bakina, O., Barnyakov, A., Blinov, V., Bobrovnikov, V., Bodrov, D., Bogomyagkov, A., Bondar, A., Boyko, I., Bu, Z. H., Cai, F. M., Cai, H., Cao, J. J., Cao, Q. H., Cao, Z., Chang, Q., Chao, K. T., Chen, D. Y., Chen, H., Chen, H. X., Chen, J. F., Chen, K., Chen, L. L., Chen, P., Chen, S. L., Chen, S. M., Chen, S., Chen, S. P., Chen, W., Chen, X. F., Chen, X., Chen, Y., Chen, Y. Q., Cheng, H. Y., Cheng, J., Cheng, S., Dai, J. P., Dai, L. Y., Dai, X. C., Dedovich, D., Denig, A., Denisenko, I., Ding, D. Z., Dong, L. Y., Dong, W. H., Druzhinin, V., Du, D. S., Du, Y. J., Du, Z. G., Duan, L. M., Epifanov, D., Fan, Y. L., Fang, S. S., Fang, Z. J., Fedotovich, G., Feng, C. Q., Feng, X., Feng, Y. T., Fu, J. L., Gao, J., Ge, P. S., Geng, C. Q., Geng, L. S., Gilman, A., Gong, L., Gong, T., Gradl, W., Gu, J. L., Escalante, A. G., Gui, L. C., Guo, F. K., Guo, J. C., Guo, J., Guo, Y. P., Guo, Z. H., Guskov, A., Han, K. L., Han, L., Han, M., Hao, X. Q., He, J. B., He, S. Q., He, X. G., He, Y. L., He, Z. B., Heng, Z. X., Hou, B. L., Hou, T. J., Hou, Y. R., Hu, C. Y., Hu, H. M., Hu, K., Hu, R. J., Hu, X. H., Hu, Y. C., Hua, J., Huang, G. S., Huang, J. S., Huang, M., Huang, Q. Y., Huang, W. Q., Huang, X. T., Huang, X. J., Huang, Y. B., Huang, Y. S., Hüsken, N., Ivanov, V., Ji, Q. P., Jia, J. J., Jia, S., Jia, Z. K., Jiang, H. B., Jiang, J., Jiang, S. Z., Jiao, J. B., Jiao, Z., Jing, H. J., Kang, X. L., Kang, X. S., Ke, B. C., Kenzie, M., Khoukaz, A., Koop, I., Kravchenko, E., Kuzmin, A., Lei, Y., Levichev, E., Li, C. H., Li, C., Li, D. Y., Li, F., Li, G., Li, H. B., Li, H., Li, H. N., Li, H. J., Li, H. L., Li, J. M., Li, J., Li, L., Li, L. Y., Li, N., Li, P. R., Li, R. H., Li, S., Li, T., Li, W. J., Li, X. H., Li, X. Q., Li, Y., Li, Y. Y., Li, Z. J., Liang, H., Liang, J. H., Liao, G. R., Liao, L. Z., Liao, Y., Lin, C. X., Lin, X. S., Liu, B. J., Liu, C. W., Liu, D., Liu, F., Liu, G. M., Liu, H. B., Liu, J., Liu, J. J., Liu, J. B., Liu, K., Liu, K. Y., Liu, L., Liu, Q., Liu, S. B., Liu, T., Liu, X., Liu, Y. W., Liu, Y., Liu, Y. L., Liu, Z. Q., Liu, Z. Y., Liu, Z. W., Logashenko, I., Long, Y., Lu, C. G., Lu, N., Lü, Q. F., Lu, Y., Lv, Z., Lukin, P., Luo, F. J., Luo, T., Luo, X. F., Lyu, H. J., Lyu, X. R., Ma, J. P., Ma, P., Ma, Y., Maas, F., Malde, S., Matvienko, D., Meng, Z. X., Mitchell, R., Dias, J. M., Nefediev, A., Nefedov, Y., Olsen, S. L., Ouyang, Q., Pakhlov, P., Pakhlova, G., Pan, X., Pan, Y., Passemar, E., Pei, Y. P., Peng, H. P., Peng, L., Peng, X. Y., Peng, X. J., Peters, K., Pivovarov, S., Pyata, E., Qi, B. B., Qi, Y. Q., Qian, W. B., Qian, Y., Qiao, C. F., Qin, J. J., Qin, L. Q., Qin, X. S., Qiu, T. L., Rademacker, J., Redmer, C. F., Sang, H. Y., Saur, M., Shan, W., Shan, X. Y., Shang, L. L., Shao, M., Shekhtman, L., Shen, C. P., Shen, J. M., Shen, Z. T., Shi, H. C., Shi, X. D., Shwartz, B., Sokolov, A., Song, J. J., Song, W. M., Song, Y., Song, Y. X., Sukharev, A., Sun, J. F., Sun, L., Sun, X. M., Sun, Y. J., Sun, Z. P., Tang, J., Tang, S. S., Tang, Z. B., Tian, C. H., Tian, J. S., Tikhonov, Y., Todyshev, K., Uglov, T., Vorobyev, V., Wan, B. D., Wang, B. L., Wang, B., Wang, D. Y., Wang, G. Y., Wang, G. L., Wang, H. L., Wang, J., Wang, J. H., Wang, J. C., Wang, M. L., Wang, R., Wang, S. B., Wang, W., Wang, W. P., Wang, X. C., Wang, X. D., Wang, X. L., Wang, X. P., Wang, X. F., Wang, Y. D., Wang, Y. P., Wang, Y. Q., Wang, Y. L., Wang, Y. G., Wang, Z. Y., Wang, Z. L., Wang, Z. G., Wei, D. H., Wei, X. L., Wei, X. M., Wen, Q. G., Wen, X. J., Wilkinson, G., Wu, B., Wu, J. J., Wu, L., Wu, P. W., Wu, T. W., Wu, Y. S., Xia, L., Xiang, T., Xiao, C. W., Xiao, D., Xiao, M., Xie, Y. H., Xing, Y., Xing, Z. Z., Xiong, X. N., Xu, F. R., Xu, J., Xu, L. L., Xu, Q. N., Xu, X. C., Xu, X. P., Xu, Y. C., Xu, Y. P., Xu, Y., Xu, Z. Z., Xuan, D. W., Xue, F. F., Yan, L., Yan, M. J., Yan, W. B., Yan, W. C., Yan, X. S., Yang, B. F., Yang, C., Yang, H. J., Yang, H. R., Yang, H. T., Yang, J. F., Yang, S. L., Yang, Y. D., Yang, Y. H., Yang, Y. S., Yang, Y. L., Yang, Z. Y., Yao, D. L., Yin, H., Yin, X. H., Yokozaki, N., You, S. Y., You, Z. Y., Yu, C. X., Yu, F. S., Yu, G. L., Yu, H. L., Yu, J. S., Yu, J. Q., Yuan, L., Yuan, X. B., Yue, Y. F., Zeng, M., Zeng, S., Zhang, A. L., Zhang, B. W., Zhang, G. Y., Zhang, G. Q., Zhang, H. J., Zhang, H. B., Zhang, J. Y., Zhang, J. L., Zhang, J., Zhang, L., Zhang, L. M., Zhang, R., Zhang, S. L., Zhang, T., Zhang, X., Zhang, Y., Zhang, Y. X., Zhang, Y. T., Zhang, Y. F., Zhang, Y. C., Zhang, Y. M., Zhang, Y. L., Zhang, Z. H., Zhang, Z. Y., Zhao, H. Y., Zhao, J., Zhao, L., Zhao, M. G., Zhao, Q., Zhao, R. G., Zhao, R. P., Zhao, Z. G., Zhao, Z. X., Zhemchugov, A., Zheng, B., Zheng, L., Zheng, Q. B., Zheng, R., Zheng, Y. H., Zhong, X. H., Zhou, H. J., Zhou, H. Q., Zhou, H., Zhou, S. H., Zhou, X., Zhou, X. K., Zhou, X. R., Zhou, Y. L., Zhou, Y., Zhou, Y. X., Zhou, Z. Y., Zhu, J. Y., Zhu, K., Zhu, R. D., Zhu, R. L., Zhu, S. H., Zhu, Y. C., Zhu, Z. A., Zhukova, V., Zhulanov, V., Zou, B. S., and Zuo, Y. B.

Subjects
High Energy Physics - Experiment, High Energy Physics - Phenomenology, Physics - Instrumentation and Detectors
Abstract

The Super $\tau$-Charm facility (STCF) is an electron-positron collider proposed by the Chinese particle physics community. It is designed to operate in a center-of-mass energy range from 2 to 7 GeV with a peak luminosity of $0.5\times 10^{35}{\rm cm}^{-2}{\rm s}^{-1}$ or higher. The STCF will produce a data sample about a factor of 100 larger than that by the present $\tau$-Charm factory -- the BEPCII, providing a unique platform for exploring the asymmetry of matter-antimatter (charge-parity violation), in-depth studies of the internal structure of hadrons and the nature of non-perturbative strong interactions, as well as searching for exotic hadrons and physics beyond the Standard Model. The STCF project in China is under development with an extensive R\&D program. This document presents the physics opportunities at the STCF, describes conceptual designs of the STCF detector system, and discusses future plans for detector R\&D and physics case studies.

Published
2023
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10. Measurement of the $e^+e^-\to\pi^+\pi^-$ cross section from threshold to 1.2 GeV with the CMD-3 detector

Author

Collaboration, CMD-3, Ignatov, F. V., Akhmetshin, R. R., Amirkhanov, A. N., Anisenkov, A. V., Aulchenko, V. M., Bashtovoy, N. S., Berkaev, D. E., Bondar, A. E., Bragin, A. V., Eidelman, S. I., Epifanov, D. A., Epshteyn, L. B., Erofeev, A. L., Fedotovich, G. V., Gorkovenko, A. O., Grancagnolo, F. J., Grebenuk, A. A., Gribanov, S. S., Grigoriev, D. N., Ivanov, V. L., Karpov, S. V., Kasaev, A. S., Kazanin, V. F., Khazin, B. I., Kirpotin, A. N., Koop, I. A., Korobov, A. A., Kozyrev, A. N., Kozyrev, E. A., Krokovny, P. P., Kuzmenko, A. E., Kuzmin, A. S., Logashenko, I. B., Lukin, P. A., Lysenko, A. P., Mikhailov, K. Yu., Obraztsov, I. V., Okhapkin, V. S., Otboev, A. V., Perevedentsev, E. A., Pestov, Yu. N., Popov, A. S., Razuvaev, G. P., Rogovsky, Yu. A., Ruban, A. A., Ryskulov, N. M., Ryzhenenkov, A. E., Semenov, A. V., Senchenko, A. I., Shatunov, P. Yu., Shatunov, Yu. M., Shebalin, V. E., Shemyakin, D. N., Shwartz, B. A., Shwartz, D. B., Sibidanov, A. L., Solodov, E. P., Talyshev, A. A., Timoshenko, M. V., Titov, V. M., Tolmachev, S. S., Vorobiov, A. I., Zemlyansky, I. M., Zhadan, D. S., Zharinov, Yu. M., Zubakin, A. S., and Yudin, Yu. V.

Subjects
High Energy Physics - Experiment
Abstract

The cross section of the process $e^+e^-\to\pi^+\pi^-$ has been measured in the center of mass energy range from 0.32 to 1.2 GeV with the CMD-3 detector at the electron-positron collider VEPP-2000. The measurement is based on a full dataset collected below 1 GeV during three data taking seasons, corresponding to an integrated luminosity of about 62 pb$^{-1}$. In the dominant $\rho$-resonance region, a systematic uncertainty of 0.7% has been reached. At energies around $\phi$-resonance the $\pi^+\pi^-$ production cross section was measured for the first time with high beam energy resolution. The forward-backward charge asymmetry in the $\pi^+\pi^-$ production has also been measured. It shows a strong deviation from the theoretical prediction based on the conventional scalar quantum electrodynamics framework, and it is in good agreement with the generalized vector-meson-dominance and dispersive-based predictions. The impact of the presented results on the evaluation of the hadronic contribution to the anomalous magnetic moment of muon is discussed., Comment: 54 pages, 36 figures; as published in Phys. Rev. D 109, 112002

Published
2023
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11. Experimental study of the $e^+e^-\to n\bar n$ process at the VEPP-2000 $e^+e^-$ collider with the SND detector

Author

Achasov, M. N., Barnyakov, A. Yu., Beloborodov, K. I., Berdyugin, A. V., Berkaev, D. E., Bogdanchikov, A. G., Botov, A. A., Chizhik, G. S., Dimova, T. V., Druzhinin, V. P., Kardapoltsev, L. V., Kharlamov, A. G., Kladov, V. A., Koop, I. A., Korol, A. A., Kovrizhin, D. P., Kupich, A. S., Lysenko, A. P., Melnikova, N. A., Muchnoi, N. Yu., Obrazovsky, A. E., Pakhtusova, E. V., Perevedentsev, E. A., Pugachev, K. V., Serednyakov, S. I., Silagadze, Z. K., Shatunov, P. Yu., Shatunov, Yu. M., Shtol, D. A., Shwartz, D. B., Surin, I. K., Usov, Yu. V., Zemlyansky, I. M., Zhabin, V. N., and Zhulanov, V. V.

Subjects
High Energy Physics - Experiment
Abstract

The process $e^+e^-\to n\bar n$ is studied in the experiment at the VEPP-2000 $e^+e^-$ collider with the SND detector. The technique of the time measurements in the multichannel NaI(Tl) electromagnetic calorimeter is used to select nnbar events. The value of the measured cross section in the center-of-mass energy range from 1.894 to 2 GeV varies from 0.5 to 0.35 nb. The effective neutron timelike form factor is derived from the measured cross section and compared with the proton form factor. The ratio of the neutron electric and magnetic form factors is obtained from the analysis of the antineutron polar angle distribution and found to be consistent with unity., Comment: 13 pages, 17 figures, 19 references

Published
2022

12. Snowmass 2021 White Paper on Upgrading SuperKEKB with a Polarized Electron Beam: Discovery Potential and Proposed Implementation

Author

Accardi, A., Asner, D. M., Atmacan, H., Baartman, R., Banerjee, Sw., Beaubien, A., Bennett, J. V., Bertemes, M., Bessner, M., Biswas, D., Bonvicini, G., Brenny, N., Briere, R. A., Browder, T. E., Chen, C., Choudhury, S., Cinabro, D., Cochran, J., Cremaldi, L. M., Deconinck, W., Di Canto, A., Dubey, S., Flood, K., Fulsom, B. G., Gaur, V., Gericke, M., Godang, R., Gu, T., Guan, Y., Guilliams, J., Hadjivasiliou, C., Hartbrich, O., Hearty, C., Hoferichter, M., Jacobs, W. W., Jaffe, D. E., Junginger, T., Kang, S., Kapitánová, L., Ketter, C., Khatri, A., Kinoshita, K., Kohani, S., Koop, I. A., Korandla, H., Sari, I. Koseoglu, Kroeger, R., Kumar, J., Kumara, K. J., Kuriki, M., Lam, T., Laycock, P. J., Diberder, F. R. Le, Li, L., Liptak, Z., Liventsev, D., Mammei, J., Martens, A., Meier, F., Miller, C., Mitra, S., Moorthy, K., Natochii, A., Nellikunnummel, N., Nishimura, K. A., Otboev, A. V., Oxford, E. R., Panta, A., Parham, K., Parker, B., Pedlar, T. K., Peng, Y., Peschke, R., Piilonen, L. E., Planche, T., Pokharel, S., Prell, S., Purwar, H., Herrmann, D. E. Ricalde, Roney, J. M., Rosenfeld, C., Sahoo, D., Sanders, D. A., Sangal, A., Savinov, V., Schneider, S., Schueler, J., Schwartz, A. J., Shatunov, Yu. M., Shebalin, V., Sibidanov, A., Signori, A., Stottler, Z. S., Strube, J., Trabelsi, K., Tripathi, S., Vahsen, S. E., Varner, G. S., Vossen, A., Wang, D., Wang, E., Wienands, U., Wood, L., Yelton, J., Zhai, Y., Zhang, B., Zhou, D., and Zomer, F.

Subjects
Physics - Accelerator Physics, High Energy Physics - Experiment
Abstract

Upgrading the SuperKEKB electron-positron collider with polarized electron beams opens a new program of precision physics at a center-of-mass energy of 10.58 GeV. This white paper describes the physics potential of this `Chiral Belle' program. It includes projections for precision measurements of $\sin^2\theta_W$ that can be obtained from independent left-right asymmetry measurements of $e^+e^-$ transitions to pairs of electrons, muons, taus, charm and b-quarks. The $\sin^2\theta_W$ precision obtainable at SuperKEKB will match that of the LEP/SLC world average, but at the centre-of-mass energy of 10.58 GeV. Measurements of the couplings for muons, charm, and $b$-quarks will be substantially improved and the existing $3\sigma$ discrepancy between the SLC $A_{LR}$ and LEP $A_{FB}^b$ measurements will be addressed. Precision measurements of neutral current universality will be more than an order of magnitude more precise than currently available. As the energy scale is well away from the $Z^0$-pole, the precision measurements will have sensitivity to the presence of a parity-violating dark sector gauge boson, $Z_{\rm dark}$. The program also enables the measurement of the anomalous magnetic moment $g-2$ form factor of the $\tau$ to be made at an unprecedented level of precision. A precision of $10^{-5}$ level is accessible with 40~ab$^{-1}$ and with more data it would start to approach the $10^{-6}$ level. This technique would provide the most precise information from the third generation about potential new physics explanations of the muon $g-2$ $4\sigma$ anomaly. Additional $\tau$ and QCD physics programs enabled or enhanced with having polarized electron beams are also discussed in this White Paper. This paper includes a summary of the path forward in R&D and next steps required to implement this upgrade and access its exciting discovery potential., Comment: 74 pages, 56 figures, contribution to Snowmass 2021

Published
2022

13. Measuring the Neutron Timelike Electromagnetic Form Factor with the SND Detector

Author

Achasov, M. N., Barnyakov, A. Yu., Bedarev, E. V., Beloborodov, K. I., Berdyugin, A. V., Berkaev, D. E., Bogdanchikov, A. G., Botov, A. A., Dimova, T. V., Druzhinin, V. P., Zhabin, V. N., Zharinov, Yu. M., Kardapoltsev, L. V., Kasaev, A. S., Kovrizhin, D. P., Koop, I. A., Korol, A. A., Kupich, A. S., Kryukov, A. P., Lysenko, A. P., Melnikova, N. A., Muchnoi, N. Yu., Obrazovsky, A. E., Pakhtusova, E. V., Pugachev, K. V., Rastigeev, S. A., Rogovsky, Yu. A., Serednyakov, S. I., Silagadze, Z. K., Surin, I. K., Usov, Yu. V., Kharlamov, A. G., Shatunov, Yu. M., and Shtol, D. A.

Published
2023
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14. Study of the Process \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${e^{+}e^{-}\to}{\eta\gamma}{\to 7}\!\gamma$$\end{document} \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sqrt{{s}}{=1.07{-}2}$$\end{document} in the Energy Range \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${e^{+}e^{-}\to}{\eta\gamma}{\to 7}\!\gamma$$\end{document} \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sqrt{{s}}{=1.07{-}2}$$\end{document} GeV

Author

Achasov, M. N., Barnyakov, A. Yu., Beloborodov, K. I., Berdyugin, A. V., Bogdanchikov, A. G., Botov, A. A., Denisov, V. S., Dimova, T. V., Druzhinin, V. P., Fomin, L. B., Kharlamov, A. G., Kardapoltsev, L. V., Kyrpotin, A. N., Koop, I. A., Korol, A. A., Kovrizhin, D. P., Kryukov, A. P., Kupich, A. S., Melnikova, N. A., Muchnoi, N. Yu., Obrazovsky, A. E., Pakhtusova, E. V., Perevedentsev, E. A., Pugachev, K. V., Rogovsky, Yu. A., Serednyakov, S. I., Silagadze, Z. K., Surin, I. K., Timoshenko, M. V., Usov, Yu. V., Zhabin, V. N., Zhulanov, V. V., Zemlyansky, I. M., Shatunov, Yu. M., Shtol, D. A., and Eminov, E. A.

Published
2023
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15. Study of the process $e^+e^- \to \eta\eta\gamma$ in the energy range $\sqrt{s} = \mbox{1.17--2.00}$ GeV with the SND detector

Author

SND Collaboration, Achasov, M. N., Barnyakov, A. Yu., Beloborodov, K. I., Berdyugin, A. V., Berkaev, D. E., Bogdanchikov, A. G., Botov, A. A., Dimova, T. V., Druzhinin, V. P., Kirpotin, A. N., Kardapoltsev, L. V., Kasaev, A. S., Kharlamov, A. G., Koop, I. A., Korol, A. A., Kovrizhin, D. P., Kupich, A. S., Martin, K. A., Melnikova, N. A., Muchnoy, N. Yu., Obrazovsky, A. E., Pakhtusova, E. V., Pugachev, K. V., Rabusov, D. V., Rogovsky, Yu. A., Senchenko, A. I., Serednyakov, S. I., Shatilov, D. N., Shatunov, Yu. M., Shtol, D. A., Shwartz, D. B., Silagadze, Z. K., Surin, I. K., Timoshenko, M. V., Usov, Yu. V., Zhabin, V. N., and Zhulanov, V. V.

Subjects
High Energy Physics - Experiment
Abstract

The process $e^+e^-\to\eta\eta\gamma$ is studied in the center-of-mass energy range 1.17-2.00 GeV using data with an integrated luminosity of 201 pb$^{-1}$collected by the SND detector at the VEPP-2000 $e^+e^-$ collider. The $e^+e^-\to\eta\eta\gamma$ cross section is measured for the first time. It is shown that the dominant mechanism of this reaction is the transition through the $\phi\eta$ intermediate state. Our result on the $e^+e^-\to\eta\eta\gamma$ cross section is consistent with the $e^+e^-\to\phi\eta$ measurement in the $\phi\to K^+ K^-$ mode. The search for radiative processes contributing to the $e^+e^-\to\eta\eta\gamma$ cross section is performed, and no significant signal is observed., Comment: 6 pages, 3 figures, to be submitted to European Physical Journal C. arXiv admin note: text overlap with arXiv:2006.05465

Published
2021

16. STCF conceptual design report (Volume 1): Physics & detector

Author

Achasov, M., Ai, X. C., An, L. P., Aliberti, R., An, Q., Bai, X. Z., Bai, Y., Bakina, O., Barnyakov, A., Blinov, V., Bobrovnikov, V., Bodrov, D., Bogomyagkov, A., Bondar, A., Boyko, I., Bu, Z. H., Cai, F. M., Cai, H., Cao, J. J., Cao, Q. H., Cao, X., Cao, Z., Chang, Q., Chao, K. T., Chen, D. Y., Chen, H., Chen, H. X., Chen, J. F., Chen, K., Chen, L. L., Chen, P., Chen, S. L., Chen, S. M., Chen, S., Chen, S. P., Chen, W., Chen, X., Chen, X. F., Chen, X. R., Chen, Y., Chen, Y. Q., Cheng, H. Y., Cheng, J., Cheng, S., Cheng, T. G., Dai, J. P., Dai, L. Y., Dai, X. C., Dedovich, D., Denig, A., Denisenko, I., Dias, J. M., Ding, D. Z., Dong, L. Y., Dong, W. H., Druzhinin, V., Du, D. S., Du, Y. J., Du, Z. G., Duan, L. M., Epifanov, D., Fan, Y. L., Fang, S. S., Fang, Z. J., Fedotovich, G., Feng, C. Q., Feng, X., Feng, Y. T., Fu, J. L., Gao, J., Gao, Y. N., Ge, P. S., Geng, C. Q., Geng, L. S., Gilman, A., Gong, L., Gong, T., Gou, B., Gradl, W., Gu, J. L., Guevara, A., Gui, L. C., Guo, A. Q., Guo, F. K., Guo, J. C., Guo, J., Guo, Y. P., Guo, Z. H., Guskov, A., Han, K. L., Han, L., Han, M., Hao, X. Q., He, J. B., He, S. Q., He, X. G., He, Y. L., He, Z. B., Heng, Z. X., Hou, B. L., Hou, T. J., Hou, Y. R., Hu, C. Y., Hu, H. M., Hu, K., Hu, R. J., Hu, W. H., Hu, X. H., Hu, Y. C., Hua, J., Huang, G. S., Huang, J. S., Huang, M., Huang, Q. Y., Huang, W. Q., Huang, X. T., Huang, X. J., Huang, Y. B., Huang, Y. S., Hüsken, N., Ivanov, V., Ji, Q. P., Jia, J. J., Jia, S., Jia, Z. K., Jiang, H. B., Jiang, J., Jiang, S. Z., Jiao, J. B., Jiao, Z., Jing, H. J., Kang, X. L., Kang, X. S., Ke, B. C., Kenzie, M., Khoukaz, A., Koop, I., Kravchenko, E., Kuzmin, A., Lei, Y., Levichev, E., Li, C. H., Li, C., Li, D. Y., Li, F., Li, G., Li, G., Li, H. B., Li, H., Li, H. N., Li, H. J., Li, H. L., Li, J. M., Li, J., Li, L., Li, L., Li, L. Y., Li, N., Li, P. R., Li, R. H., Li, S., Li, T., Li, W. J., Li, X., Li, X. H., Li, X. Q., Li, X. H., Li, Y., Li, Y. Y., Li, Z. J., Liang, H., Liang, J. H., Liang, Y. T., Liao, G. R., Liao, L. Z., Liao, Y., Lin, C. X., Lin, D. X., Lin, X. S., Liu, B. J., Liu, C. W., Liu, D., Liu, F., Liu, G. M., Liu, H. B., Liu, J., Liu, J. J., Liu, J. B., Liu, K., Liu, K. Y., Liu, K., Liu, L., Liu, Q., Liu, S. B., Liu, T., Liu, X., Liu, Y. W., Liu, Y., Liu, Y. L., Liu, Z. Q., Liu, Z. Y., Liu, Z. W., Logashenko, I., Long, Y., Lu, C. G., Lu, J. X., Lu, N., Lü, Q. F., Lu, Y., Lu, Y., Lu, Z., Lukin, P., Luo, F. J., Luo, T., Luo, X. F., Lyu, H. J., Lyu, X. R., Ma, J. P., Ma, P., Ma, Y., Ma, Y. M., Maas, F., Malde, S., Matvienko, D., Meng, Z. X., Mitchell, R., Nefediev, A., Nefedov, Y., Olsen, S. L., Ouyang, Q., Pakhlov, P., Pakhlova, G., Pan, X., Pan, Y., Passemar, E., Pei, Y. P., Peng, H. P., Peng, L., Peng, X. Y., Peng, X. J., Peters, K., Pivovarov, S., Pyata, E., Qi, B. B., Qi, Y. Q., Qian, W. B., Qian, Y., Qiao, C. F., Qin, J. J., Qin, J. J., Qin, L. Q., Qin, X. S., Qiu, T. L., Rademacker, J., Redmer, C. F., Sang, H. Y., Saur, M., Shan, W., Shan, X. Y., Shang, L. L., Shao, M., Shekhtman, L., Shen, C. P., Shen, J. M., Shen, Z. T., Shi, H. C., Shi, X. D., Shwartz, B., Sokolov, A., Song, J. J., Song, W. M., Song, Y., Song, Y. X., Sukharev, A., Sun, J. F., Sun, L., Sun, X. M., Sun, Y. J., Sun, Z. P., Tang, J., Tang, S. S., Tang, Z. B., Tian, C. H., Tian, J. S., Tian, Y., Tikhonov, Y., Todyshev, K., Uglov, T., Vorobyev, V., Wan, B. D., Wang, B. L., Wang, B., Wang, D. Y., Wang, G. Y., Wang, G. L., Wang, H. L., Wang, J., Wang, J. H., Wang, J. C., Wang, M. L., Wang, R., Wang, R., Wang, S. B., Wang, W., Wang, W. P., Wang, X. C., Wang, X. D., Wang, X. L., Wang, X. L., Wang, X. P., Wang, X. F., Wang, Y. D., Wang, Y. P., Wang, Y. Q., Wang, Y. L., Wang, Y. G., Wang, Z. Y., Wang, Z. Y., Wang, Z. L., Wang, Z. G., Wei, D. H., Wei, X. L., Wei, X. M., Wen, Q. G., Wen, X. J., Wilkinson, G., Wu, B., Wu, J. J., Wu, L., Wu, P., Wu, T. W., Wu, Y. S., Xia, L., Xiang, T., Xiao, C. W., Xiao, D., Xiao, M., Xie, K. P., Xie, Y. H., Xing, Y., Xing, Z. Z., Xiong, X. N., Xu, F. R., Xu, J., Xu, L. L., Xu, Q. N., Xu, X. C., Xu, X. P., Xu, Y. C., Xu, Y. P., Xu, Y., Xu, Z. Z., Xuan, D. W., Xue, F. F., Yan, L., Yan, M. J., Yan, W. B., Yan, W. C., Yan, X. S., Yang, B. F., Yang, C., Yang, H. J., Yang, H. R., Yang, H. T., Yang, J. F., Yang, S. L., Yang, Y. D., Yang, Y. H., Yang, Y. S., Yang, Y. L., Yang, Z. W., Yang, Z. Y., Yao, D. L., Yin, H., Yin, X. H., Yokozaki, N., You, S. Y., You, Z. Y., Yu, C. X., Yu, F. S., Yu, G. L., Yu, H. L., Yu, J. S., Yu, J. Q., Yuan, L., Yuan, X. B., Yuan, Z. Y., Yue, Y. F., Zeng, M., Zeng, S., Zhang, A. L., Zhang, B. W., Zhang, G. Y., Zhang, G. Q., Zhang, H. J., Zhang, H. B., Zhang, J. Y., Zhang, J. L., Zhang, J., Zhang, L., Zhang, L. M., Zhang, Q. A., Zhang, R., Zhang, S. L., Zhang, T., Zhang, X., Zhang, Y., Zhang, Y. J., Zhang, Y. X., Zhang, Y. T., Zhang, Y. F., Zhang, Y. C., Zhang, Y., Zhang, Y., Zhang, Y. M., Zhang, Y. L., Zhang, Z. H., Zhang, Z. Y., Zhang, Z. Y., Zhao, H. Y., Zhao, J., Zhao, L., Zhao, M. G., Zhao, Q., Zhao, R. G., Zhao, R. P., Zhao, Y. X., Zhao, Z. G., Zhao, Z. X., Zhemchugov, A., Zheng, B., Zheng, L., Zheng, Q. B., Zheng, R., Zheng, Y. H., Zhong, X. H., Zhou, H. J., Zhou, H. Q., Zhou, H., Zhou, S. H., Zhou, X., Zhou, X. K., Zhou, X. P., Zhou, X. R., Zhou, Y. L., Zhou, Y., Zhou, Y. X., Zhou, Z. Y., Zhu, J. Y., Zhu, K., Zhu, R. D., Zhu, R. L., Zhu, S. H., Zhu, Y. C., Zhu, Z. A., Zhukova, V., Zhulanov, V., Zou, B. S., and Zuo, Y. B.

Published
2024
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17. Possible studies at the first stage of the NICA collider operation with polarized and unpolarized proton and deuteron beams

Author

Abramov, V. V., Aleshko, A., Baskov, V. A., Boos, E., Bunichev, V., Dalkarov, O. D., El-Kholy, R., Galoyan, A., Guskov, A. V., Kim, V. T., Kokoulina, E., Koop, I. A., Kostenko, B. F., Kovalenko, A. D., Ladygin, V. P., Larionov, A. B., L'vov, A. I., Milstein, A. I., Nikitin, V. A., Nikolaev, N. N., Popov, A. S., Polyanskiy, V. V., Richard, J. -M., Salnikov, S. G., Shavrin, A. A., Shatunov, P. Yu., Shatunov, Yu. M., Selyugin, O. V., Strikman, M., Tomasi-Gustafsson, E., Uzhinsky, V. V., Uzikov, Yu. N., Wang, Q., Zhao, Q., and Zelenov, A. V.

Subjects
High Energy Physics - Phenomenology, High Energy Physics - Experiment
Abstract

This paper contains suggestions for experiments with usage of the Spin Physics Detector (SPD) at the first stage of the SPD NICA Programme developing at JINR. Double polarized pp-, dd- and pd- collisions at c.m.s. NN energies of 3.4-10 GeV, which will be accessible at the initial stage of experiments, allow one to study spin dependence of the NN interaction, search for multiquark states at double strangeness, charm and beauty thresholds, study the short-range structure of the deuteron. Double polarized pd scattering offer a possibility to test the Standard Model through the search for T-invariance violation., Comment: 140 pages, 44 figures, prepared for Physics of Elementary Particles and Atomic Nuclei

Published
2021
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18. Study of dynamics of the process $e^+e^-\to \pi^+\pi^-\pi^0$ in the energy range 1.15--2.00 GeV

Author

SND Collaboration, Achasov, M. N., Barnyakov, A. Yu., Baykov, A. A., Beloborodov, K. I., Berdyugin, A. V., Berkaev, D. E., Bogdanchikov, A. G., Botov, A. A., Dimova, T. V., Druzhinin, V. P., Golubev, V. B., Kirpotin, A. N., Kardapoltsev, L. V., Kasaev, A. S., Kharlamov, A. G., Koop, I. A., Korol, A. A., Kovrizhin, D. P., Kupich, A. S., Martin, K. A., Melnikova, N. A., Muchnoi, N. Yu., Obrazovsky, A. E., Pakhtusova, E. V., Pugachev, K. V., Rabusov, D. V., Rogovsky, Yu. A., Savchenko, Y. S., Senchenko, A. I., Serednyakov, S. I., Shatilov, D. N., Shatunov, Yu. M., Shtol, D. A., Shwartz, D. B., Silagadze, Z. K., Surin, I. K., Timoshenko, M. V., Usov, Yu. V., Zhabin, V. N., and Zhulanov, V. V.

Subjects
High Energy Physics - Experiment
Abstract

The dynamics of the process $ e^+e^- \to \pi^+\pi^-\pi^0 $ is studied in the energy region from 1.15 to 2.00 GeV using data accumulated with the SND detector at the VEPP-2000 $e^+e^-$ collider. The Dalitz plot distribution and $\pi^+\pi^-$ mass spectrum are analyzed in a model including the intermediate states $\rho(770)\pi$, $\rho(1450)\pi$, and $\omega\pi^0$. As a result, the energy dependences of the $\rho(770)\pi$ and $\rho(1450)\pi$ cross sections and the relative phases between the $\rho(770)\pi$ amplitude and the $\rho(1450)\pi $ and $\omega\pi^0$ amplitudes are obtained. The $\rho(1450)\pi$ cross section has a peak in the energy region of the $\omega(1650)$ resonance (1.55-1.75 GeV). In this energy range the contributions of the $\rho(770)\pi$ and $\rho(1450)\pi$ states are of the same order of magnitude. No resonance structure near 1.65 GeV is observed in the $\rho(770)\pi$ cross section. We conclude that the intermediate state $\rho(1450)\pi$ gives a significant contribution to the decay of $\omega (1650)\to\pi^+\pi^-\pi^0$, whereas the $\rho(770)\pi$ mechanism dominates in the decay $\omega(1420)\to\pi^+\pi^-\pi^0$., Comment: 9 pages, 7 figures, 3 tables

Published
2020
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19. Study of the process $e^+e^- \to \eta\pi^0\gamma$ in the energy range $\sqrt{s} = \mbox{1.05-2.00}$ GeV with the SND detector

Author

SND Collaboration, Achasov, M. N., Barnyakov, A. Yu., Baykov, A. A., Beloborodov, K. I., Berdyugin, A. V., Berkaev, D. E., Bogdanchikov, A. G., Botov, A. A., Dimova, T. V., Druzhinin, V. P., Golubev, V. B., Kirpotin, A. N., Kardapoltsev, L. V., Kasaev, A. S., Kharlamov, A. G., Koop, I. A., Korol, A. A., Kovrizhin, D. P., Kupich, A. S., Martin, K. A., Melnikova, N. A., Muchnoy, N. Yu., Obrazovsky, A. E., Pakhtusova, E. V., Pugachev, K. V., Rabusov, D. V., Rogovsky, Yu. A., Savchenko, Y. S., Senchenko, A. I., Serednyakov, S. I., Shatilov, D. N., Shatunov, Yu. M., Shtol, D. A., Shwartz, D. B., Silagadze, Z. K., Surin, I. K., Timoshenko, M. V., Usov, Yu. V., Zhabin, V. N., and Zhulanov, V. V.

Subjects
High Energy Physics - Experiment
Abstract

The process $e^+e^-\to\eta\pi^0\gamma$ is studied in the center-of-mass energy range 1.05-2.00 GeV using data with an integrated luminosity of 94.5 pb$^{-1}$ collected by the SND detector at the VEPP-2000 $e^+e^-$ collider. The $e^+e^-\to\eta\pi^0\gamma$ cross section is measured for the first time. It is shown that the dominant mechanism of this reaction is the transition through the $\omega\eta$ intermediate state. The measured cross section of the subprocess $e^+e^-\to\omega\eta\to\eta\pi^0\gamma$ is consistent with previous measurements in the $e^+e^-\to\pi^+\pi^-\pi^0\eta$ mode. It is found, with a significance of 5.6$\sigma$, that the process $e^+e^-\to\eta\pi^0\gamma$ is not completely described by hadronic vector-pseudoscalar intermediate states. The cross section of this missing contribution, which can originate from radiation processes, e. g. $e^+e^-\to a_{0}(1450)\gamma$, is measured. It is found to be 15-20 pb in the wide energy range from 1.3 to 1.9 GeV., Comment: 10 pages, 6 figures, to be submitted to European Physical Journal C

Published
2020
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20. Measurement of the $e^+e^- \to\pi^+\pi^- $ process cross section with the SND detector at the VEPP-2000 collider in the energy region $0.525<\sqrt{s}<0.883$ GeV

Author

SND Collaboration, Achasov, M. N., Baykov, A. A., Barnyakov, A. Yu., Beloborodov, K. I., Berdyugin, A. V., Berkaev, D. E., Bogdanchikov, A. G., Botov, A. A., Dimova, T. V., Druzhinin, V. P., Golubev, V. B., Kardapoltsev, L. V., Kharlamov, A. G., Koop, I. A., Korol, A. A., Kovrizhin, D. P., Kupich, A. S., Lysenko, A. P., Martin, K. A., Melnikova, N. A., Muchnoi, N. Yu., Obrazovsky, A. E., Pakhtusova, E. V., Perevedentsev, E. A., Pugachev, K. V., Savchenko, Y. S., Serednyakov, S. I., Silagadze, Z. K., Shatunov, P. Yu., Shatunov, Yu. M., Shtol, D. A., Shwartz, D. B., Surin, I. K., Usov, Yu. V., Zemlyansky, I. M., and Zhabin, V. N.

Subjects
High Energy Physics - Experiment
Abstract

The cross section of the process $e^+ e^-\to\pi^+\pi^-$ has been measured in the Spherical Neutral Detector (SND) experiment at the VEPP-2000 $e^+e^-$ collider VEPP-2000 in the energy region $525 <\sqrt[]{s} <883$ MeV. The measurement is based on data with an integrated luminosity of about 4.6 pb$^{-1}$. The systematic uncertainty of the cross section determination is 0.8 % at $\sqrt{s}>0.600$ GeV. The $\rho$ meson parameters are obtained as $m_\rho = 775.3\pm 0.5\pm 0.6$ MeV, $\Gamma_\rho = 145.6\pm 0.6\pm 0.8$ MeV, $B_{\rho\to e^+ e^-}\times B_{\rho\to\pi^+\pi^-} = (4.89\pm 0.02\pm 0.04)\times 10^{-5}$, and the parameters of the $e^+ e^-\to\omega\to\pi^+\pi^-$ process, suppressed by $G$-parity, as $B_{\omega\to e^+ e^-}\times B_{\omega\to\pi^+\pi^-}= (1.32\pm 0.06\pm 0.02)\times 10^{-6} $ and $\phi_{\rho\omega} = 110.7\pm 1.5\pm1.0$ degrees.

Published
2020
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21. Measurement of deuteron carbon vector analyzing powers in the kinetic energy range 170-380 MeV

Author

JEDI Collaboration, Müller, F., Zurek, M., Bagdasarian, Z., Barion, L., Berz, M., Ciepal, I., Ciullo, G., Dymov, S., Eversmann, D., Gaisser, M., Gebel, R., Grigoryev, K., Grzonka, D., Hejny, V., Hempelmann, N., Hetzel, J., Hinder, F., Kacharava, A., Kamerdzhiev, V., Keshelashvili, I., Koop, I., Kulikov, A., Lehrach, A., Lenisa, P., Lomidze, N., Lorentz, B., Maanen, P., Macharashvili, G., Magiera, A., Mchedlishvili, D., Nass, A., Nikolaev, N. N., Pesce, A., Prasuhn, D., Pretz, J., Rathmann, F., Rolando, V., Rosenthal, M., Saleev, A., Schmidt, V., Senichev, Y., Shergelashvili, D., Shmakova, V., Silenko, A., Slim, J., Soltner, H., Stahl, A., Stassen, R., Stephenson, E., Ströher, H., Tabidze, M., Tagliente, G., Talman, R., Trinkel, F., Uzikov, Yu., Valdau, Yu., Valetov, E., Weidemann, C., Wronska, A., and Wüstner, P.

Subjects
Nuclear Experiment, High Energy Physics - Experiment
Abstract

A measurement of vector analyzing powers in elastic deuteron-carbon scattering has been performed at the Cooler Synchrotron COSY of Forschungszentrum J\"ulich, Germany. Seven kinetic beam energies between 170 and 380 MeV have been used. A vector-polarized beam from a polarized deuteron source was injected, accelerated to the final desired energy and stored in COSY. A thin needle-shaped diamond strip was used as a carbon target, onto which the beam was slowly steered. Elastically scattered deuterons were identified in the forward direction using various layers of scintillators and straw tubes. Where data exist in the literature (at 200 and 270 MeV), excellent agreement of the angular shape was found. The beam polarization of the presented data was deduced by fitting the absolute scale of the analyzing power to these references. Our results extend the world data set and are necessary for polarimetry of future electric dipole moment searches at storage rings. They will as well serve as an input for theoretical description of polarized hadron-hadron scattering.

Published
2020

22. Storage Ring to Search for Electric Dipole Moments of Charged Particles -- Feasibility Study

Author

Abusaif, F., Aggarwal, A., Aksentev, A., Alberdi-Esuain, B., Andres, A., Atanasov, A., Barion, L., Basile, S., Berz, M., Böhme, C., Böker, J., Borburgh, J., Canale, N., Carli, C., Ciepał, I., Ciullo, G., Contalbrigo, M., De Conto, J. -M., Dymov, S., Felden, O., Gaisser, M., Gebel, R., Giese, N., Gooding, J., Grigoryev, K., Grzonka, D., Tahar, M. Haj, Hahnraths, T., Heberling, D., Hejny, V., Hetzel, J., Hölscher, D., Javakhishvili, O., Jorat, L., Kacharava, A., Kamerdzhiev, V., Karanth, S., Keshelashvili, I., Koop, I., Kulikov, A., Laihem, K., Lamont, M., Lehrach, A., Lenisa, P., Lomidze, I., Lomidze, N., Lorentz, B., Macharashvili, G., Magiera, A., Makino, K., Martin, S., Mchedlishvili, D., Meißner, U. -G., Metreveli, Z., Michaud, J., Müller, F., Nass, A., Natour, G., Nikolaev, N., Nogga, A., Okropiridze, D., Pesce, A., Poncza, V., Prasuhn, D., Pretz, J., Rathmann, F., Ritman, J., Rosenthal, M., Saleev, A., Schott, M., Sefzick, T., Senichev, Y., Shankar, R., Shergelashvili, D., Shmakova, V., Siddique, S., Silenko, A., Simon, M., Slim, J., Soltner, H., Stahl, A., Stassen, R., Stephenson, E., Straatmann, H., Ströher, H., Tabidze, M., Tagliente, G., Talman, R., Uzikov, Y., Valdau, Y., Valetov, E., Vilella, E., Vitz, M., Vossebeld, J., Wagner, T., Weidemann, C., Wirzba, A., Wrońska, A., Wüstner, P., Zupranski, P., and Żurek, M.

Subjects
High Energy Physics - Experiment, Nuclear Experiment, Physics - Accelerator Physics
Abstract

The proposed method exploits charged particles confined as a storage ring beam (proton, deuteron, possibly $^3$He) to search for an intrinsic electric dipole moment (EDM) aligned along the particle spin axis. Statistical sensitivities could approach 10$^{-29}$ e$\cdot$cm. The challenge will be to reduce systematic errors to similar levels. The ring will be adjusted to preserve the spin polarisation, initially parallel to the particle velocity, for times in excess of 15 minutes. Large radial electric fields, acting through the EDM, will rotate the polarisation from the longitudinal to the vertical direction. The slow rise in the vertical polarisation component, detected through scattering from a target, signals the EDM. The project strategy is outlined. A stepwise plan is foreseen, starting with ongoing COSY activities that demonstrate technical feasibility. Achievements to date include reduced polarization measurement errors, long horizontal plane polarization lifetimes, and control of the polarization direction through feedback from scattering measurements. The project continues with a proof-of-capability measurement (precursor experiment; first direct deuteron EDM measurement), an intermediate prototype ring (proof-of-principle; demonstrator for key technologies), and finally a high-precision electric-field storage ring., Comment: 243 pages

Published
2019
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23. Possibility to investigate P-parity violation in nuclear collisions at facility NICA

Author

Koop, I. A., Milstein, A. I., Nikolaev, N. N., Popov, A. S., Salnikov, S. G., Shatunov, P. Yu., and Shatunov, Yu. M.

Subjects
High Energy Physics - Experiment, Physics - Accelerator Physics
Abstract

A possible experimental setup for measuring the effect of parity violation in the interaction of the polarized proton or deuteron beams with an unpolarized target is discussed. One possibility is investigation of scattering of the proton or deuteron polarized beams on a thick internal target in one of the rings of the NICA collider. In this case, the spin of a circulating particles is transformed into a mode precessing in the horizontal plane using an RF flipper. The effect of parity violation will be studied by measuring the correlation of the interaction cross section of particles and the direction of their spins. In an alternative approach, the flipper transforms the spins of particles into a horizontal plane and the beam is extracted into the channel in a certain phase of the precession. In this more traditional experimental setup, the total cross section of the passage of particles through a dense target is measured, depending on the sign of the helicity of the polarization of the beam., Comment: 12 pages, 2 figures

Published
2019

24. Measurement of the $e^{+}e^{-}\rightarrow\eta\pi^{+}\pi^{-}$ cross section with the CMD-3 detector at the VEPP-2000 collider

Author

Gribanov, S. S., Popov, A. S., Akhmetshin, R. R., Amirkhanov, A. N., Anisenkov, A. V., Aulchenko, V. M., Banzarov, V. Sh., Bashtovoy, N. S., Berkaev, D. E., Bondar, A. E., Bragin, A. V., Eidelman, S. I., Epifanov, D. A., Epshteyn, L. B., Erofeev, A. L., Fedotovich, G. V., Gayazov, S. E., Grancagnolo, F. J., Grebenuk, A. A., Grigoriev, D. N., Ignatov, F. V., Ivanov, V. L., Karpov, S. V., Kazanin, V. F., Kirpotin, A. N., Koop, I. A., Korobov, A. A., Kovalenko, O. A., Kozyrev, A. N., Kozyrev, E. A., Krokovny, P. P., Kuzmenko, A. E., Kuzmin, A. S., Logashenko, I. B., Lukin, P. A., Mikhailov, K. Yu., Okhapkin, V. S., Otboev, A. V., Pestov, Yu. N., Razuvaev, G. P., Rogovsky, Yu. A., Ruban, A. A., Ryskulov, N. M., Ryzhenenkov, A. E., Semenov, A. V., Senchenko, A. I., Shatunov, Yu. M., Shatunov, P. Yu., Shebalin, V. E., Shemyakin, D. N., Shwartz, B. A., Shwartz, D. B., Sibidanov, A. L., Solodov, E. P., Titov, V. M., Talyshev, A. A., Tolmachev, S. S., Vorobiov, A. I., Zemlyansky, I. M., and Yudin, Yu. V.

Subjects
High Energy Physics - Experiment
Abstract

The cross section of the process $e^{+}e^{-}\rightarrow\eta\pi^{+}\pi^{-}$ is measured using the data collected with the CMD-$3$ detector at the VEPP-$2000$ collider in the center-of-mass energy range from $1.1$ to $2.0$ GeV. The decay mode $\eta\rightarrow\gamma\gamma$ is used for $\eta$ meson reconstruction in the data sample corresponding to an integrated luminosity of $78.3$ pb$^{-1}$. The energy dependence of the $e^{+}e^{-}\rightarrow\eta\pi^{+}\pi^{-}$ cross section is fitted within the framework of vector meson dominance in order to extract the $\Gamma(\rho(1450)\rightarrow{^{+}e^{-}})\mathcal{B}(\rho(1450)\rightarrow\eta\pi^{+}\pi^{-})$ and the $\Gamma(\rho(1700)\rightarrow{e^{+}e^{-}})\mathcal{B}(\rho(1700)\rightarrow\eta\pi^{+}\pi^{-})$ products. Based on conservation of vector current, the analysed data are used to test the relationship between the $e^{+}e^{-}\rightarrow\eta\pi^{+}\pi^{-}$ cross section and the spectral function in $\tau^-\rightarrow\eta\pi^-\pi^0\nu_\tau$ decay. The $e^{+}e^{-}\rightarrow\eta\pi^{+}\pi^{-}$ cross section measured with the CMD-$3$ detector is in good agreement with the previous measurements.

Published
2019
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25. Study of the process $e^+e^-{\to}K^+K^-\eta$ with the CMD-3 detector at the VEPP-2000 collider

Author

Ivanov, V. L., Fedotovich, G. V., Akhmetshin, R. R., Amirkhanov, A. N., Anisenkov, A. V., Aulchenko, V. M., Banzarov, V. Sh., Bashtovoy, N. S., Berkaev, D. E., Bondar, A. E., Bragin, A. V., Eidelman, S. I., Epifanov, D. A., Epshteyn, L. B., Erofeev, A. L., Gayazov, S. E., Grebenuk, A. A., Gribanov, S. S., Grigoriev, D. N., Ignatov, F. V., Karpov, S. V., Kasaev, A. S., Kazanin, V. F., Koop, I. A., Korobov, A. A., Kozyrev, A. N., Kozyrev, E. A., Krokovny, P. P., Kuzmenko, A. E., Kuzmin, A. S., Logashenko, I. B., Lukin, P. A., Lysenko, A. P., Mikhailov, K. Yu., Okhapkin, V. S., Perevedentsev, E. A., Pestov, Yu. N., Popov, A. S., Razuvaev, G. P., Ruban, A. A., Ryskulov, N. M., Ryzhenenkov, A. E., Semenov, A. V., Shatunov, Yu. M., Shebalin, V. E., Shemyakin, D. N., Shwartz, B. A., Shwartz, D. B., Sibidanov, A. L., Solodov, E. P., Timoshenko, M. V., Titov, V. M., Talyshev, A. A., Tolmachev, S. S., Vorobiov, A. I., and Yudin, Yu. V.

Subjects
High Energy Physics - Experiment
Abstract

The process $e^+e^-{\to}K^+K^-\eta$ has been studied in the center-of-mass energy range from 1.59 to 2.007\,GeV using the data sample of 59.5 pb$^{-1}$, collected with the CMD-3 detector at the VEPP-2000 $e^+e^-$ collider in 2011, 2012 and 2017. The $K^+K^-\eta$ final state is found to be dominated by the contribution of the $\phi(1020)\eta$ intermediate state. The cross section of the process $e^+e^-{\to}\phi(1020)\eta$ has been measured with a systematic uncertainty of 5.1$\%$ on the base of 3009 $\pm$ 67 selected events. The obtained cross section has been used to calculate the contribution to the anomalous magnetic moment of the muon: $a_{\mu}^{\phi\eta}(E<1.8\, {\rm GeV})=(0.321 \pm 0.015_{\rm stat} \pm 0.016_{\rm syst}) \times 10^{-10}$, $a_{\mu}^{\phi\eta}(E<2.0\, {\rm GeV})=(0.440 \pm 0.015_{\rm stat} \pm 0.022_{\rm syst}) \times 10^{-10}$. From the cross section approximation the $\phi(1680)$ meson parameters have been determined with better statistical precision, than in previous studies.

Published
2019
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26. Search for direct production of the $f_1(1285)$ resonance in $e^+e^-$ collisions

Author

SND Collaboration, Achasov, M. N., Barnyakov, A. Yu., Beloborodov, K. I., Berdyugin, A. V., Berkaev, D. E., Bogdanchikov, A. G., Botov, A. A., Dimova, T. V., Druzhinin, V. P., Golubev, V. B., Kardapoltsev, L. V., Kasaev, A. S., Kharlamov, A. G., Koop, I. A., Korol, A. A., Kovrizhin, D. P., Koshuba, S. V., Kupich, A. S., Litvinov, R. A., Lysenko, A. P., Martin, K. A., Melnikova, N. A., Muchnoi, N. Yu., Obrazovsky, A. E., Pakhtusova, E. V., Perevedentsev, E. A., Pugachev, K. V., Serednyakov, S. I., Silagadze, Z. K., Shatunov, P. Yu., Shatunov, Yu. M., Shtol, D. A., Shwartz, D. B., Surin, I. K., Usov, Yu. V., Zemlyansky, I. M., Zhabin, V. N., and Zhulanov, V. V.

Subjects
High Energy Physics - Experiment
Abstract

A search for direct production of the $f_1(1285)$ resonance in $e^+e^-$ annihilation is performed with the SND detector at the VEPP-2000 $e^+e^-$ collider. The analysis is based on data with an integrated luminosity of 15.1 pb$^{-1}$ accumulated in the center-of-mass energy range 1.2--1.4 GeV. Two $e^+e^-\to f_1(1285)$ candidate events are found at the peak of the resonance and zero events beyond the resonance. The significance of the $e^+e^-\to f_1(1285)$ signal is $2.5\sigma$. The cross section at the maximum of the resonance is found to be $\sigma(e^+e^-\to f_1)=45^{+33}_{-24}$ pb. The corresponding branching fraction $B(f_1(1285)\to e^+e^-)=(5.1^{+3.7}_{-2.7})\times 10^{-9}$. We consider this result as a first indication of the process $e^+e^-\to f_1(1285)$. The measured branching fraction is consistent with the theoretical prediction., Comment: 11 pages, 4 figures

Published
2019
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27. Feasibility Study for an EDM Storage Ring

Author

Abusaif, F., Aggarwal, A., Aksentev, A., Alberdi-Esuain, B., Barion, L., Basile, S., Berz, M., Beyß, M., Böhme, C., Böker, J., Borburgh, J., Carli, C., Ciepał, I., Ciullo, G., Contalbrigo, M., De Conto, J. -M., Dymov, S., Engels, R., Felden, O., Gagoshidze, M., Gaisser, M., Gebel, R., Giese, N., Grigoryev, K., Grzonka, D., Hanraths, T., Hanhart, C., Heberling, D., Hejny, V., Hetzel, J., Hölscher, D., Javakhishvili, O., Kacharava, A., Karanth, S., Käseberg, C., Kamerdzhiev, V., Keshelashvili, I., Koop, I., Kulikov, A., Laihem, K., Lamont, M., Lehrach, A., Lenisa, P., Lomidze, N., Lorentz, B., Macharashvili, G., Magiera, A., Maier, R., Makino, K., Martin, S., Mchedlishvili, D., Meißner, U. -G., Metreveli, Z., Michaud, J., Müller, F., Nass, A., Natour, G., Nikolaev, N., Nogga, A., Pesce, A., Poncza, V., Prasuhn, D., Pretz, J., Rathmann, F., Ritman, J., Rosenthal, M., Saleev, A., Schott, M., Sefzick, T., Senichev, Y., Shergelashvili, D., Shmakova, V., Siddique, S., Silenko, A., Simon, M., Slim, J., Soltner, H., Stahl, A., Stassen, R., Stephenson, E., Straatmann, H., Ströher, H., Tabidze, M., Tagliente, G., Tahar, M., Talman, R., Uzikov, Yu., Valdau, Yu., Valetov, E., Wagner, T., Weidemann, C., Wilkin, C., Wirzba, A., Wrońska, A., and Wüstner, P.

Subjects
Physics - Accelerator Physics, High Energy Physics - Experiment
Abstract

This project exploits charged particles confined as a storage ring beam (proton, deuteron, possibly $^3$He) to search for an intrinsic electric dipole moment (EDM, $\vec d$) aligned along the particle spin axis. Statistical sensitivities can approach $10^{-29}$~e$\cdot$cm. The challenge will be to reduce systematic errors to similar levels. The ring will be adjusted to preserve the spin polarization, initially parallel to the particle velocity, for times in excess of 15 minutes. Large radial electric fields, acting through the EDM, will rotate the polarization ($\vec d \times\vec E$). The slow rise in the vertical polarization component, detected through scattering from a target, signals the EDM. The project strategy is outlined. It foresees a step-wise plan, starting with ongoing COSY activities that demonstrate technical feasibility. Achievements to date include reduced polarization measurement errors, long horizontal-plane polarization lifetimes, and control of the polarization direction through feedback from the scattering measurements. The project continues with a proof-of-capability measurement (precursor experiment; first direct deuteron EDM measurement), an intermediate prototype ring (proof-of-principle; demonstrator for key technologies), and finally the high precision electric-field storage ring.

Published
2018

28. Measurement of the $e^+e^- \to \pi^0\gamma$ cross section in the energy range 1.075--2 GeV at SND

Author

Achasov, M. N., Barnyakov, A. Yu., Beloborodov, K. I., Berdyugin, A. V., Berkaev, D. E., Bogdanchikov, A. G., Botov, A. A., Dimova, T. V., Druzhinin, V. P., Golubev, V. B., Kardapoltsev, L. V., Kasaev, A. S., Kharlamov, A. G., Koop, I. A., Korol, A. A., Kovrizhin, D. P., Koshuba, S. V., Kupich, A. S., Litvinov, R. A., Martin, K. A., Melnikova, N. A., Muchnoi, N. Yu., Obrazovsky, A. E., Pakhtusova, E. V., Pugachev, K. V., Rogovsky, Yu. A., Senchenko, A. I., Serednyakov, S. I., Silagadze, Z. K., Shatunov, P. Yu., Shatunov, Yu. M., Shtol, D. A., Shwartz, D. B., Surin, I. K., Usov, Yu. V., Vasiljev, A. V., and Zhulanov, V. V.

Subjects
High Energy Physics - Experiment
Abstract

The process $e^+e^- \to \pi^0\gamma$ is studied with the SND detector at the VEPP-2000 $e^+e^-$ collider. Basing on data with an integrated luminosity of 41 pb$^{-1}$ recorded in 2010-2012 we measure the $e^+e^- \to \pi^0\gamma$ cross section in the center-of-mass energy range from 1.075 up to 2 GeV. In the range 1.4-2.0 GeV the process $e^+e^- \to \pi^0\gamma$ is studied for the first time., Comment: 7 pages, 5 figures. arXiv admin note: text overlap with arXiv:1601.08061

Published
2018
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29. Search for the process $\mathbf{e^+e^- \to\eta}$

Author

Achasov, M. N., Barnyakov, A. Yu., Beloborodov, K. I., Berdyugin, A. V., Berkaev, D. E., Bogdanchikov, A. G., Botov, A. A., Dimova, T. V., Druzhinin, V. P., Golubev, V. B., Kardapoltsev, L. V., Kasaev, A. S., Kharlamov, A. G., Koop, I. A., Korneev, L. A., Korol, A. A., Kovrizhin, D. P., Koshuba, S. V., Kupich, A. S., Litvinov, R. A., Martin, K. A., Melnikova, N. A., Muchnoi, N. Yu., Obrazovsky, A. E., Pakhtusova, E. V., Pugachev, K. V., Rogovsky, Yu. A., Senchenko, A. I., Serednyakov, S. I., Silagadze, Z. K., Shatilov, D. N., Shatunov, Yu. M., Shtol, D. A., Shwartz, D. B., Surin, I. K., Usov, Yu. V., Vasiljev, A. V., Zhabin, V. N., and Zhulanov, V. V.

Subjects
High Energy Physics - Experiment
Abstract

A search for the rare decay $\eta \rightarrow e^+e^-$ is performed using the inverse process $e^+e^- \rightarrow \eta$ in the decay mode $\eta\to\pi^0\pi^0\pi^0 $. We analyze data with an integrated luminosity of 654 nb$^{-1} $ accumulated at the VEPP-2000 $e^+e^-$ collider with the SND detector at the center-of-mass energy $E=m_\eta c ^2\approx 548 $ MeV, and set the upper limit $ {\cal B} (\eta \rightarrow e^+ e^-) < 7 \times 10^{-7} $ at the 90\% confidence level., Comment: 9 pages, 4 figures

Published
2018
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30. Phase Measurement for Driven Spin Oscillations in a Storage Ring

Author

Hempelmann, N., Hejny, V., Pretz, J., Soltner, H., Augustyniak, W., Bagdasarian, Z., Bai, M., Barion, L., Berz, M., Chekmenev, S., Ciullo, G., Dymov, S., Eversmann, D., Gaisser, M., Gebel, R., Grigoryev, K., Grzonka, D., Guidoboni, G., Heberling, D., Hetzel, J., Hinder, F., Kacharava, A., Kamerdzhiev, V., Keshelashvili, I., Koop, I., Kulikov, A., Lehrach, A., Lenisa, P., Lomidze, N., Lorentz, B., Maanen, P., Macharashvili, G., Magiera, A., Mchedlishvili, D., Mey, S., Müller, F., Nass, A., Nikolaev, N. N., Nioradze, M., Pesce, A., Prasuhn, D., Rathmann, F., Rosenthal, M., Saleev, A., Schmidt, V., Semertzidis, Y., Shmakova, Y. Senichev V., Silenko, A., Slim, J., Stahl, A., Stassen, R., Stephenson, E., Stockhorst, H., Ströher, H., Tabidze, M., Tagliente, G., Talman, R., Engblom, P. Thörngren, Trinkel, F., Uzikov, Yu., Valdau, Yu., Valetov, E., Vassiliev, A., Weidemann, C., Wrońska, A., Wüstner, P., Zuprański, P., and Żurek, M.

Subjects
Physics - Accelerator Physics, 13.40.Em, 11.30.Er, 29.20.D, 29.20.dg, 29.20.db
Abstract

This paper reports the first simultaneous measurement of the horizontal and vertical components of the polarization vector in a storage ring under the influence of a radio frequency (rf) solenoid. The experiments were performed at the Cooler Synchrotron COSY in J\"ulich using a vector polarized, bunched $0.97\,\textrm{GeV/c}$ deuteron beam. Using the new spin feedback system, we set the initial phase difference between the solenoid field and the precession of the polarization vector to a predefined value. The feedback system was then switched off, allowing the phase difference to change over time, and the solenoid was switched on to rotate the polarization vector. We observed an oscillation of the vertical polarization component and the phase difference. The oscillations can be described using an analytical model. The results of this experiment also apply to other rf devices with horizontal magnetic fields, such as Wien filters. The precise manipulation of particle spins in storage rings is a prerequisite for measuring the electric dipole moment (EDM) of charged particles.

Published
2018
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31. Measurement of the $e^+e^- \to \eta\pi^+\pi^-$ cross section with the SND detector at the VEPP-2000 collider

Author

Achasov, M. N., Barnyakov, A. Yu., Beloborodov, K. I., Berdyugin, A. V., Berkaev, D. E., Bogdanchikov, A. G., Botov, A. A., Dimova, T. V., Druzhinin, V. P., Golubev, V. B., Kardapoltsev, L. V., Kharlamov, A. G., Koop, I. A., Korol, A. A., Kovrizhin, D. P., Koshuba, S. V., Kupich, A. S., Lysenko, A. P., Martin, K. A., Melnikova, N. A., Muchnoi, N. Yu., Obrazovsky, A. E., Pakhtusova, E. V., Perevedentsev, E. A., Pugachev, K. V., Rogozina, E. V., Serednyakov, S. I., Silagadze, Z. K., Shatunov, Yu. M., Shatunov, P. Yu., Shtol, D. A., Surin, I. K., Tikhonov, Yu. A., Usov, Yu. V., Vasiljev, A. V., and Zemlyansky, I. M.

Subjects
High Energy Physics - Experiment
Abstract

The $e^+e^- \to \eta\pi^+\pi^-$ cross section is measured at the SND detector in the $\eta$ decay mode $\eta\to 3\pi^0$. The analysis is based on the data sample with an integrated luminosity of 32.7 pb$^{-1}$ collected at the VEPP-2000 $e^+e^-$ collider in the center-of-mass energy range $\sqrt{s}=1.075-2.000$ GeV. The data obtained in the $\eta\to 3\pi^0$ decay mode are found to be in agreement with the previous SND measurements in the $\eta\to \gamma\gamma$ mode. Therefore the measurements in the two modes are combined., Comment: 8 pages, 5 figures

Published
2017
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32. Measurement of the $\mathbf{e^+e^- \rightarrow K_S K_L \pi^0}$ cross section in the energy range $\mathbf{\sqrt{s}=1.3-2.0}$ GeV

Author

Achasov, M. N., Aulchenko, V. M., Barnyakov, A. Yu., Beloborodov, K. I., Berdyugin, A. V., Berkaev, D. E., Bogdanchikov, A. G., Botov, A. A., Dimova, T. V., Druzhinin, V. P., Golubev, V. B., Kardapoltsev, L. V., Kasaev, A. S., Kharlamov, A. G., Kirpotin, A. N., Koop, I. A., Korneev, L. A., Korol, A. A., Kovrizhin, D. P., Koshuba, S. V., Kupich, A. S., Melnikova, N. A., Martin, K. A., Obrazovsky, A. E., Otboev, A. V., Pakhtusova, E. V., Pugachev, K. V., Rogovsky, Yu. A., Senchenko, A. I., Serednyakov, S. I., Silagadze, Z. K., Shatunov, Yu. M., Shtol, D. A., Shwartz, D. B., Surin, I. K., Usov, Yu. V., and Vasiljev, A. V.

Subjects
High Energy Physics - Experiment
Abstract

The $e^+e^- \rightarrow K_S K_L \pi^0$ cross section is measured in the center-of-mass energy range $\sqrt{s}=1.3-2.0$ GeV. The analysis is based on the data sample with an integrated luminosity of 33.5 pb$^{-1}$ collected with the SND detector at the VEPP-2000 $e^+e^-$ collider., Comment: 8 pages, 3 figures, accepted for publication in Phys. Rev. D

Published
2017
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33. Study of the process $e^+e^- \to K^+K^-$ in the center-of-mass energy range 1010--1060~MeV with the CMD-3 detector

Author

Kozyrev, E. A., Solodov, E. P., Akhmetshin, R. R., Amirkhanov, A. N., Anisenkov, A. V., Aulchenko, V. M., Banzarov, V. S., Bashtovoy, N. S., Berkaev, D. E., Bondar, A. E., Bragin, A. V., Eidelman, S. I., Epifanov, D. A., Epshteyn, L. B., Erofeev, A. L., Fedotovich, G. V., Gayazov, S. E., Grebenuk, A. A., Gribanov, S. S., Grigoriev, D. N., Ignatov, F. V., Ivanov, V. L., Karpov, S. V., Kasaev, A. S., Kazanin, V. F., Korobov, A. A., Koop, I. A., Kozyrev, A. N., Krokovny, P. P., Kuzmenko, A. E., Kuzmin, A. S., Logashenko, I. B., Lukin, P. A., Lysenko, A. P., Mikhailov, K. Yu., Okhapkin, V. S., Perevedentsev, E. A., Pestov, Yu. N., Popov, A. S., Razuvaev, G. P., Rogovsky, Yu. A., Ruban, A. A., Ryskulov, N. M., Ryzhenenkov, A. E., Shebalin, V. E., Shemyakin, D. N., Shwartz, B. A., Shwartz, D. B., Sibidanov, A. L., Shatunov, Yu. M., Talyshev, A. A., Vorobiov, A. I., and Yudin, Yu. V.

Subjects
High Energy Physics - Experiment
Abstract

The process $e^+e^- \to K^+K^-$ has been studied using $1.7 \times 10^6$ events from a data sample corresponding to an integrated luminosity of 5.7 pb$^{-1}$ collected with the CMD-3 detector in the center-of-mass energy range 1010--1060 MeV. The cross section measured with an about 2\% systematic uncertainty and it is used to calculate the contribution to the anomalous magnetic moment of the muon $a_{\mu}^{K^+K^-} = (19.33 \pm 0.40) \times 10^{-10}$, and to obtain the $\phi(1020)$ meson parameters. We consider the relationship between the $e^+e^- \to K^+K^-$ and $e^+e^- \to K^0_SK^0_L$ cross sections and compare it to the theoretical expectations.

Published
2017
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34. Correction of magnetic optics and beam trajectory using LOCO based algorithm with expanded experimental data sets

Author

Romanov, A., Edstrom Jr., D., Emanov, F. A., Koop, I. A., Perevedentsev, E. A., Rogovsky, Yu. A., Shwartz, D. B., and Valishev, A.

Subjects
Physics - Accelerator Physics
Abstract

Precise beam based measurement and correction of magnetic optics is essential for the successful operation of accelerators. The LOCO algorithm is a proven and reliable tool, which in some situations can be improved by using a broader class of experimental data. The standard data sets for LOCO include the closed orbit responses to dipole corrector variation, dispersion, and betatron tunes. This paper discusses the benefits from augmenting the data with four additional classes of experimental data: the beam shape measured with beam profile monitors; responses of closed orbit bumps to focusing field variations; betatron tune responses to focusing field variations; BPM-to-BPM betatron phase advances and beta functions in BPMs from turn-by-turn coordinates of kicked beam. All of the described features were implemented in the Sixdsimulation software that was used to correct the optics of the VEPP-2000 collider, the VEPP-5 injector booster ring, and the FAST linac., Comment: 10 pages, 12 figures, submitted to PRAB

Published
2017

35. Phase locking the spin precession in a storage ring

Author

Hempelmann, N., Hejny, V., Pretz, J., Stephenson, E., Augustyniak, W., Bagdasarian, Z., Bai, M., Barion, L., Berz, M., Chekmenev, S., Ciullo, G., Dymov, S., Etzkorn, F. -J., Eversmann, D., Gaisser, M., Gebel, R., Grigoryev, K., Grzonka, D., Guidoboni, G., Hanraths, T., Heberling, D., Hetzel, J., Hinder, F., Kacharava, A., Kamerdzhiev, V., Keshelashvili, I., Koop, I., Kulikov, A., Lehrach, A., Lenisa, P., Lomidze, N., Lorentz, B., Maanen, P., Macharashvili, G., Magiera, A., Mchedlishvili, D., Mey, S., Müller, F., Nass, A., Nikolaev, N. N., Pesce, A., Prasuhn, D., Rathmann, F., Rosenthal, M., Saleev, A., Schmidt, V., Semertzidis, Y., Shmakova, V., Silenko, A., Slim, J., Soltner, H., Stahl, A., Stassen, R., Stockhorst, H., Ströher, H., Tabidze, M., Tagliente, G., Talman, R., Engblom, P. Thörngren, Trinkel, F., Uzikov, Yu., Valdau, Yu., Valetov, E., Vassiliev, A., Weidemann, C., Wrońska, A., Wüstner, P., Zuprański, P., and Żurek, M.

Subjects
Physics - Accelerator Physics
Abstract

This letter reports the successful use of feedback from a spin polarization measurement to the revolution frequency of a 0.97 GeV/$c$ bunched and polarized deuteron beam in the Cooler Synchrotron (COSY) storage ring in order to control both the precession rate ($\approx 121$ kHz) and the phase of the horizontal polarization component. Real time synchronization with a radio frequency (rf) solenoid made possible the rotation of the polarization out of the horizontal plane, yielding a demonstration of the feedback method to manipulate the polarization. In particular, the rotation rate shows a sinusoidal function of the horizontal polarization phase (relative to the rf solenoid), which was controlled to within a one standard deviation range of $\sigma = 0.21$ rad. The minimum possible adjustment was 3.7 mHz out of a revolution frequency of 753 kHz, which changes the precession rate by 26 mrad/s. Such a capability meets a requirement for the use of storage rings to look for an intrinsic electric dipole moment of charged particles.

Published
2017
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36. Spin tune mapping as a novel tool to probe the spin dynamics in storage rings

Author

Saleev, A., Nikolaev, N. N., Rathmann, F., Augustyniak, W., Bagdasarian, Z., Bai, M., Berz, M., Chekmenev, S., Ciullo, G., Dymov, S., Eversmann, D., Gaisser, M., Gebel, R., Grigoryev, K., Grzonka, D., Guidoboni, G., Heberling, D., Hempelmann, N., Hejny, V., Hetzel, J., Hinder, F., Kacharava, A., Kamerdzhiev, V., Keshelashvili, I., Koop, I., Kulikov, A., Lehrach, A., Lenisa, P., Lomidze, N., Lorentz, B., Maanen, P., Macharashvili, G., Mchedlishvili, D., Magiera, A., Mey, S., Nass, A., Pesce, A., Prasuhn, D., Pretz, J., Rosenthal, M., Schmidt, V., Semertzidis, Y., Senichev, Y., Shmakova, V., Silenko, A., Slim, J., Stahl, A., Stassen, R., Stephenson, E., Stockhorst, H., Ströher, H., Engblom, P. Thörngren, Tabidze, M., Tagliente, G., Talman, R., Trinkel, F., Uzikov, Yu., Valdau, Yu., Valetov, E., Vassiliev, A., Weidemann, C., Wrońska, A., Wüstner, P., and Zuprański, P.

Subjects
Physics - Accelerator Physics, Nuclear Experiment, Physics - Instrumentation and Detectors
Abstract

Precision experiments, such as the search for electric dipole moments of charged particles using storage rings, demand for an understanding of the spin dynamics with unprecedented accuracy. The ultimate aim is to measure the electric dipole moments with a sensitivity up to 15 orders in magnitude better than the magnetic dipole moment of the stored particles. This formidable task requires an understanding of the background to the signal of the electric dipole from rotations of the spins in the spurious magnetic fields of a storage ring. One of the observables, especially sensitive to the imperfection magnetic fields in the ring is the angular orientation of stable spin axis. Up to now, the stable spin axis has never been determined experimentally, and in addition, the JEDI collaboration for the first time succeeded to quantify the background signals that stem from false rotations of the magnetic dipole moments in the horizontal and longitudinal imperfection magnetic fields of the storage ring. To this end, we developed a new method based on the spin tune response of a machine to artificially applied longitudinal magnetic fields. This novel technique, called \textit{spin tune mapping}, emerges as a very powerful tool to probe the spin dynamics in storage rings. The technique was experimentally tested in 2014 at the cooler synchrotron COSY, and for the first time, the angular orientation of the stable spin axis at two different locations in the ring has been determined to an unprecedented accuracy of better than $2.8\mu$rad., Comment: 32 pages, 15 figures, 7 tables

Published
2017
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37. Study of the Process $e^+e^-\to \pi^+\pi^-\pi^+\pi^-$ IN THE C.M. Energy Range 920--1060 MeV with the CMD-3 Detector

Author

Akhmetshin, R. R., Amirkhanov, A. N., Anisenkov, A. V., Aulchenko, V. M., Banzarov, V. Sh., Bashtovoy, N. S., Berkaev, D. E., Bondar, A. E., Bragin, A. V., Eidelman, S. I., Epifanov, D. A., Epshteyn, L. B., Erofeev, A. L., Fedotovich, G. V., Gayazov, S. E., Grebenuk, A. A., Gribanov, S. S., Grigoriev, D. N., Ignatov, F. V., Ivanov, V. L., Karpov, S. V., Kasaev, A. S., Kazanin, V. F., Koop, I. A., Kovalenko, O. A., Korobov, A. A., Kozyrev, A. N., Kozyrev, E. A., Krokovny, P. P., Kuzmenko, A. E., Kuzmin, A. S., Logashenko, I. B., Lysenko, A. P., Lukin, P. A., Mikhailov, K. Yu., Okhapkin, V. S., Pestov, Yu. N., Perevedentsev, E. A., Popov, A. S., Razuvaev, G. P., Rogovsky, Yu. A., Ruban, A. A., Ryskulov, N. M., Ryzhenenkov, A. E., Shebalin, V. E., Shemyakin, D. N., Shwartz, B. A., Shwartz, D. B., Sibidanov, A. L., Shatunov, Yu. M., Solodov, E. P., Titov, V. M., Talyshev, A. A., Vorobiov, A. I., and Yudin, Yu. V.

Subjects
High Energy Physics - Experiment
Abstract

A cross section of the process $e^+e^- \to \pipi\pipi$ has been measured using 6798$\pm$93 signal events from a data sample corresponding to an integrated luminosity of 9.8 pb$^{-1}$ collected with the CMD-3 detector in the center-of-mass energy range 920--1060 MeV. The measured cross section exhibits an interference pattern of the $\phi(1020)\to\pipi\pipi$ decay with a non-resonant process $e^+e^- \to \pipi\pipi$, from which we obtain the branching fraction of the doubly suppressed decays (by G-parity and OZI rule): $\BR(\phi\to\pipi\pipi) = (6.5\pm2.7\pm1.6)\times 10^{-6}$., Comment: 16 pages, 6 figures

Published
2016
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38. Design of beam optics for the Future Circular Collider e+e- -collider rings

Author

Oide, K., Aiba, M., Aumon, S., Benedikt, M., Blondel, A., Bogomyagkov, A., Boscolo, M., Burkhardt, H., Cai, Y., Doblhammer, A., Haerer, B., Holzer, B., Jowett, J. M., Koop, I., Koratzinos, M., Levichev, E., Medina, L., Ohmi, K., Papaphilippou, Y., Piminov, P., Shatilov, D., Sinyatkin, S., Sullivan, M., Wenninger, J., Wienands, U., Zhou, D., and Zimmermann, F.

Subjects
Physics - Accelerator Physics, High Energy Physics - Experiment
Abstract

A beam optics scheme has been designed for the Future Circular Collider-e+e- (FCC-ee). The main characteristics of the design are: beam energy 45 to 175 GeV, 100 km circumference with two interaction points (IPs) per ring, horizontal crossing angle of 30 mrad at the IP and the crab-waist scheme [1] with local chromaticity correction. The crab-waist scheme is implemented within the local chromaticity correction system without additional sextupoles, by reducing the strength of one of the two sextupoles for vertical chromatic correction at each side of the IP. So-called "tapering" of the magnets is applied, which scales all fields of the magnets according to the local beam energy to compensate for the effect of synchrotron radiation (SR) loss along the ring. An asymmetric layout near the interaction region reduces the critical energy of SR photons on the incoming side of the IP to values below 100 keV, while matching the geometry to the beam line of the FCC proton collider (FCC-hh) [2] as closely as possible. Sufficient transverse/longitudinal dynamic aperture (DA) has been obtained, including major dynamical effects, to assure an adequate beam lifetime in the presence of beamstrahlung and top-up injection. In particular, a momentum acceptance larger than +/-2% has been obtained, which is better than the momentum acceptance of typical collider rings by about a factor of 2. The effects of the detector solenoids including their compensation elements are taken into account as well as synchrotron radiation in all magnets. The optics presented in this paper is a step toward a full conceptual design for the collider. A number of issues have been identified for further study.

Published
2016
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39. Updated measurement of the $e^+e^- \to \omega \pi^0 \to \pi^0\pi^0\gamma$ cross section with the SND detector

Author

Achasov, M. N., Barnyakov, A. Yu., Beloborodov, K. I., Berdyugin, A. V., Berkaev, D. E., Bogdanchikov, A. G., Botov, A. A., Dimova, T. V., Druzhinin, V. P., Golubev, V. B., Kardapoltsev, L. V., Kasaev, A. S., Kharlamov, A. G., Kirpotin, A. N., Kovrizhin, D. P., Koop, I. A., Korol, A. A., Koshuba, S. V., Martin, K. A., Obrazovsky, A. E., Pakhtusova, E. V., Rogovsky, Yu. A., Senchenko, A. I., Serednyakov, S. I., Silagadze, Z. K., Shatunov, Yu. M., Shtol, D. A., Shwartz, D. B., Skrinsky, A. N., Surin, I. K., and Vasiljev, A. V.

Subjects
High Energy Physics - Experiment
Abstract

We analyze a 37 pb$^{-1}$ data sample collected with the SND detector at the VEPP-2000 $e^+e^-$ collider in the center-of-mass energy range 1.05--2.00 GeV and present an updated measurement of the $e^+e^- \to \omega \pi^0 \to \pi^0\pi^0\gamma$ cross section. In particular, we correct the mistake in radiative correction calculation made in our previous measurement based on a part of the data. The measured cross section is fitted with the vector meson dominance model with three $\rho$-like states and used to test the conserved vector current hypothesis in the $\tau^-\to\omega\pi^-\nu_{\tau}$ decay., Comment: 7 pages, 3 figures, 3 tables

Published
2016
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40. Measurement of the $\mathbf{e^+e^-\to K^+K^-}$ cross section in the energy range $\mathbf{\sqrt{s}=1.05-2.0}$ GeV

Author

Achasov, M. N., Aulchenko, V. M., Barnyakov, A. Yu., Barnyakov, M. Yu., Beloborodov, K. I., Berdyugin, A. V., Berkaev, D. E., Bogdanchikov, A. G., Botov, A. A., Buzykaev, A. R., Dimova, T. V., Druzhinin, V. P., Golubev, V. B., Kardapoltsev, L. V., Kharlamov, A. G., Kononov, S. A., Koop, I. A., Korol, A. A., Koshuba, S. V., Kovrizhin, D. P., Kravchenko, E. A., Kupich, A. S., Lysenko, A. P., Martin, K. A., Obrazovsky, A. E., Onuchin, A. P., Otboyev, A. V., Pakhtusova, E. V., Perevedentsev, E. A., Rogovsky, Yu. A., Serednyakov, S. I., Shatunov, Yu. M., Shatunov, P. Yu., Shtol, D. A., Silagadze, Z. K., Skrinsky, A. N., Surin, I. K., Tikhonov, Yu. A., Usov, Yu. V., Vasiljev, A. V., and Zemlyansky, I. M.

Subjects
High Energy Physics - Experiment
Abstract

The $e^+e^-\to K^+K^-$ cross section is measured in the center-of-mass energy range $1.05-2.00$ GeV at the SND detector. The measurement is based on data with an integrated luminosity of 35 pb$^{-1}$ collected at the VEPP-2000 $e^+e^-$-collider. The obtained results are consistent with the previous most accurate data obtained in the BABAR experiment and have a comparable accuracy., Comment: 11 pages, 8 eps figures, 3 tables

Published
2016
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41. Measurement of the $e^+e^- \to \omega\eta$ cross section below $\sqrt{s}=2$ GeV

Author

Achasov, M. N., Barnyakov, A. Yu., Beloborodov, K. I., Berdyugin, A. V., Bogdanchikov, A. G., Botov, A. A., Dimova, T. V., Druzhinin, V. P., Golubev, V. B., Kardapoltsev, L. V., Kasaev, A. S., Kharlamov, A. G., Kirpotin, A. N., Kovrizhin, D. P., Koop, I. A., Korol, A. A., Koshuba, S. V., Kupich, A. S., Martin, K. A., Melnikova, N. A., Obrazovsky, A. E., Pakhtusova, E. V., Senchenko, A. I., Serednyakov, S. I., Silagadze, Z. K., Shatunov, Yu. M., Shtol, D. A., Shwartz, D. B., Skrinsky, A. N., Surin, I. K., Tikhonov, Yu. A., and Vasiljev, A. V.

Subjects
High Energy Physics - Experiment
Abstract

The cross section for the process $e^+e^- \to \omega\eta$ is measured in the center-of-mass energy range 1.34--2.00 GeV. The analysis is based on data collected with the SND detector at the VEPP-2000 $e^+e^-$ collider. The measured $e^+e^- \to \omega\eta$ cross section is the most accurate to date. A significant discrepancy is observed between our data and previous BABAR measurement., Comment: 15 pages, 5 figures, 3 tables

Published
2016
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42. Study of the process $e^+e^-\to\omega\eta\pi^0$ in the energy range $\sqrt{s} <2$ GeV with the SND detector

Author

Achasov, M. N., Aulchenko, V. M., Barnyakov, A. Yu., Beloborodov, K. I., Berdyugin, A. V., Berkaev, D. E., Bogdanchikov, A. G., Botov, A. A., Dimova, T. V., Druzhinin, V. P., Golubev, V. B., Kardapoltsev, L. V., Kharlamov, A. G., Koop, I. A., Korol, A. A., Kovrizhin, D. P., Koshuba, S. V., Kupich, A. S., Lysenko, A. P., Melnikova, N. A., Martin, K. A., Pakhtusova, E. V., Obrazovsky, A. E., Perevedentsev, E. A., Rogovsky, Yu. A., Serednyakov, S. I., Silagadze, Z. K., Shatunov, Yu. M., Shatunov, P. Yu., Shtol, D. A., Skrinsky, A. N., Surin, I. K., Tikhonov, Yu. A., Usov, Yu. V., Vasiljev, A. V., and Zemlyansky, I. M.

Subjects
High Energy Physics - Experiment
Abstract

The process $e^+e^-\to\omega\eta\pi^0$ is studied in the energy range $1.45-2.00$ GeV using data with an integrated luminosity of 33 pb$^{-1}$ accumulated by the SND detector at the $e^+e^-$ collider VEPP-2000. The $e^+e^-\to\omega\eta\pi^0$ cross section is measured for the first time. The cross section has a threshold near 1.75 GeV. Its value is about 2 nb in the energy range $1.8-2.0$ GeV. The dominant intermediate state for the process $e^+e^- \to \omega\eta\pi^0$ is found to be $\omega a_0(980)$., Comment: 7 pages, 6 figures

Published
2016
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43. Study of the reaction $e^+e^- \to \pi^0\gamma$ with the SND detector at the VEPP-2M collider

Author

Achasov, M. N., Beloborodov, K. I., Berdyugin, A. V., Bogdanchikov, A. G., Dimova, T. V., Druzhinin, V. P., Golubev, V. B., Koop, I. A., Korol, A. A., Pakhtusova, S. V. Koshuba. E. V., Serednyakov, S. I., Shatunov, Yu. M., Silagadze, Z. K., Skrinsky, A. N., Usov, Yu. V., and Vasiljev, A. V.

Subjects
High Energy Physics - Experiment
Abstract

The process $e^+e^- \to \pi^0\gamma$ has been studied in the experiment with the SND detector at the VEPP-2M $e^+e^-$ collider. The $e^+e^- \to \pi^0\gamma$ cross section has been measured in the center-of-mass energy range from 0.60 to 1.38 GeV. The cross section is well described by the vector meson dominance model. From the fit to the cross section data we have determined the branching fractions $B(\rho\to\pi^0\gamma)=(4.20\pm0.52)\times10^{-4}$, $B(\omega\to\pi^0\gamma)=(8.88\pm0.18)\%$, $B(\phi\to\pi^0\gamma)=(1.367\pm0.072)\times10^{-3}$, and the relative phase between the $\rho$ and $\omega$ amplitudes $\varphi_{\rho}=(-12.7\pm4.5)^\circ$. Our data on the process $e^+e^- \to \pi^0\gamma$ are the most accurate to date., Comment: 12 pages, 5 figures

Published
2016
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44. Experimental study of the e+e-→nn¯e+e- process at the VEPP-2000 e+e-→nn¯e+e- collider with the SND detector

Author

Achasov, M. N., Barnyakov, A. Yu., Beloborodov, K. I., Berdyugin, A. V., Berkaev, D. E., Bogdanchikov, A. G., Botov, A. A., Chizhik, G. S., Dimova, T. V., Druzhinin, V. P., Kardapoltsev, L. V., Kharlamov, A. G., Kladov, V. A., Koop, I. A., Korol, A. A., Kovrizhin, D. P., Kupich, A. S., Lysenko, A. P., Melnikova, N. A., Muchnoi, N. Yu., Obrazovsky, A. E., Pakhtusova, E. V., Perevedentsev, E. A., Pugachev, K. V., Serednyakov, S. I., Silagadze, Z. K., Shatunov, P. Yu., Shatunov, Yu. M., Shtol, D. A., Shwartz, D. B., Surin, I. K., Usov, Yu. V., Zemlyansky, I. M., Zhabin, V. N., and Zhulanov, V. V.

Published
2022
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46. Measurement of the $e^+e^- \to K^+K^-\pi^+\pi^-$ cross section with the CMD-3 detector at the VEPP-2000 collider

Author

Shemyakin, D. N., Fedotovich, G. V., Akhmetshin, R. R., Amirkhanov, A. N., Anisenkov, A. V., Aulchenko, V. M., Banzarov, V. Sh., Bashtovoy, N. S., Bondar, A. E., Bragin, A. V., Eidelman, S. I., Epifanov, D. A., Epshteyn, L. B., Erofeev, A. L., Gayazov, S. E., Grebenuk, A. A., Gribanov, S. S., Grigoriev, D. N., Ignatov, F. V., Ivanov, V. L., Karpov, S. V., Kazanin, V. F., Koop, I. A., Korobov, A. A., Kovalenko, O. A., Kozyrev, A. N., Kozyrev, E. A., Krokovny, P. P., Kuzmenko, A. E., Kuzmin, A. S., Logashenko, I. B., Lysenko, A. P., Lukin, P. A., Mikhailov, K. Yu., Okhapkin, V. S., Pestov, Yu. N., Perevedentsev, E. A., Popov, A. S., Razuvaev, G. P., Rogovsky, Yu. A., Ruban, A. A., Ryskulov, N. M., Ryzhenenkov, A. E., Shebalin, V. E., Shwartz, B. A., Shwartz, D. B., Sibidanov, A. L., Shatunov, Yu. M., Solodov, E. P., Titov, V. M., Talyshev, A. A., Vorobiov, A. I., Yudin, Yu. V., and Zemlyansky, I. M.

Subjects
High Energy Physics - Experiment, Nuclear Experiment
Abstract

The process $e^+e^- \to K^+K^-\pi^+\pi^-$ has been studied in the center-of-mass energy range from 1500 to 2000\,MeV using a data sample of 23 pb$^{-1}$ collected with the CMD-3 detector at the VEPP-2000 $e^+e^-$ collider. Using about 24000 selected events, the $e^+e^- \to K^+K^-\pi^+\pi^-$ cross section has been measured with a systematic uncertainty decreasing from 11.7\% at 1500-1600\,MeV to 6.1\% above 1800\,MeV. A preliminary study of $K^+K^-\pi^+\pi^-$ production dynamics has been performed.

Published
2015
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47. Study of the process $e^+e^-\to p\bar{p}$ in the c.m. energy range from threshold to 2 GeV with the CMD-3 detector

Author

Akhmetshin, R. R., Amirkhanov, A. N., Anisenkov, A. V., Aulchenko, V. M., Banzarov, V. Sh., Bashtovoy, N. S., Berkaev, D. E., Bondar, A. E., Bragin, A. V., Eidelman, S. I., Epifanov, D. A., Epshteyn, L. B., Erofeev, A. L., Fedotovich, G. V., Gayazov, S. E., Grebenuk, A. A., Gribanov, S. S., Grigoriev, D. N., Gromov, E. M., Ignatov, F. V., Ivanov, V. L., Karpov, S. V., Kasaev, A. S., Kazanin, V. F., Khazin, B. I., Kirpotin, A. N., Koop, I. A., Kovalenko, O. A., Kozyrev, A. N., Kozyrev, E. A., Krokovny, P. P., Kuzmenko, A. E., Kuzmin, A. S., Logashenko, I. B., Lukin, P. A., Mikhailov, K. Yu., Okhapkin, V. S., Otboev, A. V., Pestov, Yu. N., Pivovarov, S. G., Popov, A. S., Razuvaev, G. P., Romanov, A. L., Ruban, A. A., Ryskulov, N. M., Ryzhenenkov, A. E., Shebalin, V. E., Shemyakin, D. N., Shwartz, B. A., Shwartz, D. B., Sibidanov, A. L., Shatunov, P. Yu., Shatunov, Yu. M., Solodov, E. P., Titov, V. M., Talyshev, A. A., Vorobiov, A. I., Yudin, Yu. V., and Zharinov, Yu. M.

Subjects
High Energy Physics - Experiment
Abstract

Using a data sample of 6.8 pb$^{-1}$ collected with the CMD-3 detector at the VEPP-2000 $e^+e^-$ collider we select about 2700 events of the $e^+e^- \to p\bar{p}$ process and measure its cross section at 12 energy ponts with about 6\% systematic uncertainty. From the angular distribution of produced nucleons we obtain the ratio $|G_{E}/G_{M}| = 1.49 \pm 0.23 \pm 0.30$.

Published
2015
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48. On a search for the $\eta \rightarrow e^+ e^-$ decay at the VEPP-2000 $e^+e^-$ collider

Author

Achasov, M. N., Barnyakov, A. Yu., Berdyugin, K. I. Beloborodov A. V., Bogdanchikov, A. G., Botov, A. A., Dimova, T. V., Druzhinin, V. P., Golubev, V. B., Kardapoltsev, L. V., Kharlamov, A. G., Koop, I. A., Korneev, L. A., Korol, A. A., Kovrizhin, D. P., Kupich, A. S., Lysenko, A. P., Martin, K. A., Muchnoi, N. Yu., Obrazovsky, A. E., Pakhtusova, E. V., Perevedentsev, E. A., Rogovsky, Yu. A., Senchenko, A. I., Serednyakov, S. I., Silagadze, Z. K., Shatunov, Yu. M., Shtol, D. A., Shwartz, D. B., Skrinsky, A. N., Surin, I. K., Tikhonov, Yu. A., Usov, Yu. V., Vasiljev, A. V., and Zemlyansky, I. M.

Subjects
High Energy Physics - Experiment
Abstract

A sensitivity of the VEPP-2000 $e^+e^-$ collider in a search for the rare decay $\eta \rightarrow e^+ e^-$ has been studied. The inverse reaction $e^+ e^- \rightarrow \eta$ is proposed for this search. We have analyzed a data sample with an integrated luminosity of 108 nb$^{-1}$ collected with the SND detector in the center-of-mass energy range 520-580 MeV and found no background events for the reaction $e^+ e^- \rightarrow \eta$ in the decay mode $\eta\to\pi^0\pi^0\pi^0$. In the absence of background, a sensitivity to ${\cal B}(\eta \rightarrow e^+ e^-)$ of $10^{-6}$ can be reached during two weeks of VEPP-2000 operation. Such a sensitivity is better than the current upper limit on ${\cal B}(\eta \rightarrow e^+ e^-)$ by a factor of 2.3., Comment: 5 pages, 2 figures, accepted for publication in JETP Letters

Published
2015
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49. Search for the $\eta^{\prime}\to e^+e^-$ decay with the SND detector

Author

Achasov, M. N., Aulchenko, V. M., Barnyakov, A. Yu., Beloborodov, K. I., Berdyugin, A. V., Berkaev, D. E., Bogdanchikov, A. G., Botov, A. A., Dimova, T. V., Druzhinin, V. P., Golubev, V. B., Kardapoltsev, L. V., Kasaev, A. S., Kharlamov, A. G., Kirpotin, A. N., Koop, I. A., Korol, A. A., Koshuba, S. V., Kovrizhin, D. P., Kupich, A. S., Martin, K. A., Muchnoi, N. Yu., Obrazovsky, A. E., Otboev, A. V., Pakhtusova, E. V., Senchenko, A. I., Serednyakov, S. I., Shatunov, P. Yu., Shatunov, Yu. M., Shtol, D. A., Shwartz, D. B., Silagadze, Z. K., Surin, I. K., Tikhonov, Yu. A., Usov, Yu. V., Vasiljev, A. V., and Zemlyansky, I. M.

Subjects
High Energy Physics - Experiment
Abstract

A search for the process $e^+e^- \to \eta^\prime$ has been performed with the SND detector at the VEPP-2000 $e^+e^-$ collider. The data were accumulated at the center-of-mass energy of $957.78\pm 0.06$ MeV with an integrated luminosity of about 2.9 pb$^{-1}$. For reconstruction of the $\eta^\prime$ meson five decay chains have been used: $\eta^{\prime}\to\eta\pi^+\pi^-$ followed by the $\eta$ decays to $\gamma\gamma$ and $3\pi^0 $, and $\eta^{\prime} \to \eta\pi^0\pi^0$ followed by the $\eta$ decays to $\pi^+\pi^-\pi^0$, $\gamma\gamma$, and $3\pi^0$. As a result, the upper limit has been set on the $\eta^\prime$ electronic width: $\Gamma_{\eta^{\prime}\to e^+e^-} < 0.0020$ eV at the 90\% confidence level., Comment: 12 pages, 6 figures

Published
2015
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50. New method for a continuous determination of the spin tune in storage rings and implications for precision experiments

Author

Eversmann, D., Hejny, V., Hinder, F., Kacharava, A., Pretz, J., Rathmann, F., Rosenthal, M., Trinkel, F., Andrianov, S., Augustyniak, W., Bagdasarian, Z., Bai, M., Bernreuther, W., Bertelli, S., Berz, M., Bsaisou, J., Chekmenev, S., Chiladze, D., Ciullo, G., Contalbrigo, M., de Vries, J., Dymov, S., Engels, R., Esser, F. M., Felden, O., Gaisser, M., Gebel, R., Glückler, H., Goldenbaum, F., Grigoryev, K., Grzonka, D., Guidoboni, G., Hanhart, C., Heberling, D., Hempelmann, N., Hetzel, J., Hipple, R., Hölscher, D., Ivanov, A., Kamerdzhiev, V., Kamys, B., Keshelashvili, I., Khoukaz, A., Koop, I., Krause, H-J., Krewald, S., Kulikov, A., Lehrach, A., Lenisa, P., Lomidze, N., Lorentz, B., Maanen, P., Macharashvili, G., Magiera, A., Maier, R., Makino, K., Marianski, B., Mchedlishvili, D., Meißner, Ulf-G., Mey, S., Nass, A., Natour, G., Nikolaev, N., Nioradze, M., Nogga, A., Nowakowski, K., Pesce, A., Prasuhn, D., Ritman, J., Rudy, Z., Saleev, A., Semertzidis, Y., Senichev, Y., Shmakova, V., Silenko, A., Slim, J., Soltner, H., Stahl, A., Stassen, R., Statera, M., Stephenson, E., Stockhorst, H., Straatmann, H., Ströher, H., Tabidze, M., Talman, R., Engblom, P. Thörngren, Trzcinski, A., Uzikov, Yu., Valdau, Yu., Valetov, E., Vassiliev, A., Weidemann, C., Wilkin, C., Wirzba, A., Wronska, A., Wüstner, P., Zakrzewska, M., Zaplatin, E., Zupranski, P., and Zyuzin, D.

Subjects
Physics - Accelerator Physics, Nuclear Experiment
Abstract

A new method to determine the spin tune is described and tested. In an ideal planar magnetic ring, the spin tune - defined as the number of spin precessions per turn - is given by $\nu_s = \gamma G$ (gamma is the Lorentz factor, $G$ the magnetic anomaly). For 970 MeV/c deuterons coherently precessing with a frequency of ~120 kHz in the Cooler Synchrotron COSY, the spin tune is deduced from the up-down asymmetry of deuteron carbon scattering. In a time interval of 2.6 s, the spin tune was determined with a precision of the order $10^{-8}$, and to $1 \cdot 10^{-10}$ for a continuous 100 s accelerator cycle. This renders the presented method a new precision tool for accelerator physics: controlling the spin motion of particles to high precision is mandatory, in particular, for the measurement of electric dipole moments of charged particles in a storage ring., Comment: 6 pages, 6 figures

Published
2015
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