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269 results on '"Murayama, R."'

1. Measurement of the mesonic decay branch of the $\bar{K}\!N\!N$ quasi-bound state

Author

Yamaga, T., Ajimura, S., Asano, H., Beer, G., Bhang, H., Bragadireanu, M., Buehler, P., Busso, L., Cargnelli, M., Choi, S., Curceanu, C., Enomoto, S., Fujioka, H., Fujiwara, Y., Fukuda, T., Guaraldo, C., Hashimoto, T., Hayano, R. S., Hiraiwa, T., Iio, M., Iliescu, M., Inoue, K., Ishiguro, Y., Ishikawa, T., Ishimoto, S., Itahashi, K., Iwai, M., Iwasaki, M., Kanno, K., Kato, K., Kato, Y., Kawasaki, S., Kienle, P., Kou, H., Ma, Y., Marton, J., Matsuda, Y., Mizoi, Y., Morra, O., Murayama, R., Nagae, T., Noumi, H., Ohnishi, H., Okada, S., Outa, H., Piscicchia, K., Sada, Y., Sakaguchi, A., Sakuma, F., Sato, M., Scordo, A., Sekimoto, M., Shi, H., Shirotori, K., Sirghi, D., Sirghi, F., Suzuki, S., Suzuki, T., Tanida, K., Tatsuno, H., Tokuda, M., Tomono, D., Toyoda, A., Tsukada, K., Doce, O. Vazquez, Widmann, E., Yamazaki, T., Yim, H., Zhang, Q., and Zmeskal, J.

Subjects
Nuclear Experiment, Nuclear Theory
Abstract

We conducted measurements of $K^- + {^3{\rm He}} \to \pi \!Y \!N + N'$ reactions using a $1~{\rm GeV}/c$ $K^-$-beam, with the objective of understanding the broad decay width of $\bar{K} \!N \!N$ (approximately twice as broad as that of $\Lambda(1405)$ considered to be the $\bar{K} \!N$ quasi-bound state). We successfully reproduced distributions of the $\pi \! Y \! N$ invariant mass and momentum transfer for $\pi \! Y \! N$ using model fitting functions for $\bar{K} \!N \!N$ formation and quasi-free $\bar{K}$ absorption (${\rm QF}_{\bar{K}-{\rm abs}}$) processes. The model can describe the experimental data quite well, and four $\bar{K} \! N \! N \to \pi \! Y \! N $ cross-sections were obtained. The results indicate that mesonic decay is the dominant decay branch of $\bar{K} \! N \! N$. The results also suggest that $\Gamma_{\pi \Lambda N} \sim \Gamma_{\pi \Sigma N}$, which indicates that the $I_{\bar{K} \! N}=1$ absorption channel, in addition to the $I_{\bar{K} \! N}=0$ absorption channel, substantially contribute to the $\bar{K} \! N \! N$ decay, making the $\bar{K} \! N \! N$ state approximately twice as unstable as $\Lambda$(1405).

Published
2024

2. Precise lifetime measurement of $^4_\Lambda$H hypernucleus using in-flight $^4$He$(K^-, \pi^0)^4_\Lambda$H reaction

Author

Akaishi, T., Asano, H., Chen, X., Clozza, A., Curceanu, C., Del Grande, R., Guaraldo, C., Han, C., Hashimoto, T., Iliescu, M., Inoue, K., Ishimoto, S., Itahashi, K., Iwasaki, M., Ma, Y., Miliucci, M., Murayama, R., Noumi, H., Ohnishi, H., Okada, S., Outa, H., Piscicchia, K., Sakaguchi, A., Sakuma, F., Sato, M., Scordo, A., Shirotori, K., Sirghi, D., Sirghi, F., Suzuki, S., Tanida, K., Toda, T., Tokuda, M., Yamaga, T., Yuan, X., Zhang, P., Zhang, Y., and Zhang, H.

Subjects
Nuclear Experiment
Abstract

We present a new measurement of the $^4_\Lambda$H hypernuclear lifetime using in-flight $K^-$ + $^4$He $\rightarrow$ $^4_\Lambda$H + $\pi^0$ reaction at the J-PARC hadron facility. We demonstrate, for the first time, the effective selection of the hypernuclear bound state using only the $\gamma$-ray energy decayed from $\pi^0$. This opens the possibility for a systematic study of isospin partner hypernuclei through comparison with data from ($K^-$, $\pi^-$) reaction. As the first application of this method, our result for the $^4_\Lambda$H lifetime, $\tau(^4_\Lambda \mathrm{H}) = 206 \pm 8 (\mathrm{stat.}) \pm 12 (\mathrm{syst.})\ \mathrm{ps}$, is one of the most precise measurements to date. We are also preparing to measure the lifetime of the hypertriton ($^3_\Lambda$H) using the same setup in the near future.

Published
2023
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3. Pole position of $\Lambda(1405)$ measured in $d(K^-,n)\pi\Sigma$ reactions

Author

Collaboration, J-PARC E31, Aikawa, S., Ajimura, S., Akaishi, T., Asano, H., Beer, G., Berucci, C., Bragadireanu, M., Buehler, P., Busso, L., Cargnelli, M., Choi, S., Curceanu, C., Enomoto, S., Fujioka, H., Fujiwara, Y., Fukuda, T., Guaraldo, C., Hashimoto, T., Hayano, R. S., Hiraiwa, T., Iio, M., Iliescu, M., Inoue, K., Ishiguro, Y., Ishimoto, S., Ishikawa, T., Itahashi, K., Iwai, M., Iwasaki, M., Kanno, K., Kato, K., Kato, Y., Kawasaki, S., Kienle, P., Komatsu, Y., Kou, H., Ma, Y., Marton, J., Matsuda, Y., Mizoi, Y., Morra, O., Murayama, R., Nagae, T., Noumi, H., Ohnishi, H., Okada, S., Omar, Z., Outa, H., Piscicchia, K., Sada, Y., Sakaguchi, A., Sakuma, F., Sato, M., Scordo, A., Sekimoto, M., Shi, H., Shirotori, K., Sirghi, D., Sirghi, F., Suzuki, K., Suzuki, S., Suzuki, T., Tanida, K., Tatsuno, H., Tokiyasu, A. O., Tokuda, M., Tomono, D., Toyoda, A., Tsukada, K., Vazquez-Doce, O., Widmann, E., Yamaga, T., Yamazaki, T., Yim, H., Zhang, Q., and Zmeskal, J.

Subjects
Nuclear Experiment
Abstract

We measured a set of $\pi^\pm\Sigma^\mp$, $\pi^0\Sigma^0$, and $\pi^-\Sigma^0$ invariant mass spectra below and above the $\bar{K}N$ mass threshold in $K^-$-induced reactions on deuteron. We deduced the $S$-wave $\bar{K}N\rightarrow\pi\Sigma$ and $\bar{K}N\rightarrow\bar{K}N$ scattering amplitudes in the isospin 0 channel in the framework of a $\bar{K}N$ and $\pi\Sigma$ coupled channel. We find that a resonance pole corresponding to $\Lambda(1405)$ is located at 1417.7$^{+6.0}_{-7.4}$(fitting errors)$^{+1.1}_{-1.0}$(systematic errors) + $[-26.1^{+6.0}_{-7.9}$(fitting errors)$^{+1.7}_{-2.0}$(systematic errors)]$i$ MeV/$c^2$, closer to the $\bar{K}N$ mass threshold than the value determined by the Particle Data Group., Comment: 8 pages, 5 figures

Published
2022
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4. Recent results and future prospects of kaonic nuclei at J-PARC

Author

Sakuma, F., Ajimura, S., Akaishi, T., Asano, H., Bazzi, M., Beer, G., Bhang, H., Bragadireanu, M., Buehler, P., Busso, L., Cargnelli, M., Choi, S., Clozza, A., Curceanu, C., Enomoto, S., Fujioka, H., Fujiwara, Y., Fukuda, T., Guaraldo, C., Hashimoto, T., Hayano, R. S., Hiraiwa, T., Iio, M., Iliescu, M., Inoue, K., Ishiguro, Y., Ishikawa, T., Ishimoto, S., Itahashi, K., Iwasaki, M., Iwai, M., Kanno, K., Kato, K., Kato, Y., Kawasaki, S., Kienle, P., Kou, H., Ma, Y., Marton, J., Matsuda, Y., Miliucci, M., Mizoi, Y., Morra, O., Murayama, R., Nagae, T., Noumi, H., Ohnishi, H., Okada, S., Outa, H., Ozawa, K., Piscicchia, K., Sada, Y., Sakaguchi, A., Sato, M., Scordo, A., Sekimoto, M., Shi, H., Shirotori, K., Simon, M., Sirghi, D., Sirghi, F., Suzuki, S., Suzuki, T., Tanida, K., Tatsuno, H., Tokuda, M., Tomono, D., Toyoda, A., Tsukada, K., Doce, O. Vázquez, Widmann, E., Yamaga, T., Yamazaki, T., Yoshida, C., Zhang, Q., and Zmeskal, J.

Subjects
Nuclear Experiment, Nuclear Theory
Abstract

$\bar K$-nuclear bound systems, kaonic nuclei, have been widely discussed as products of the strongly attractive $\bar K N$ interaction in $I = 0$ channels. Recently, we demonstrated that kaonic nuclei can be produced via in-flight $(K^-,N)$ reactions using the low-momentum DC kaon beam at the J-PARC E15 experiment. We observed the simplest kaonic nuclei, $K^-pp$, having a much deeper binding energy than normal nuclei. For further studies, we have proposed a series of experimental programs for the systematic investigation of light kaonic nuclei, from $\bar K N$ ($\Lambda(1405)$) to $\bar K NNNN$. In the new experiment approved as J-PARC E80, we will measure the $\bar K NNN$ ($A=3$) system as a first step toward a comprehensive study., Comment: 10 pages, 5 figures, proceedings of the 8th Asia-Pacific Conference on Few-Body Problems in Physics (APFB2020), accepted for publication in Fwe-Body Systems

Published
2021
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5. Study of the $K_L \!\to\! \pi^0 \nu \overline{\nu}$ Decay at the J-PARC KOTO Experiment

Author

KOTO Collaboration, Ahn, J. K., Beckford, B., Campbell, M., Chen, S. H., Comfort, J., Dona, K., Farrington, M. S., Hanai, K., Hara, N., Haraguchi, H., Hsiung, Y. B., Hutcheson, M., Inagaki, T., Isoe, M., Kamiji, I., Kato, T., Kim, E. J., Kim, J. L., Kim, H. M., Komatsubara, T. K., Kotera, K., Lee, S. K., Lee, J. W., Lim, G. Y., Lin, Q. S., Lin, C., Luo, Y., Mari, T., Masuda, T., Matsumura, T., Mcfarland, D., McNeal, N., Miyazaki, K., Murayama, R., Nakagiri, K., Nanjo, H., Nishimiya, H., Noichi, Y., Nomura, T., Nunes, T., Ohsugi, M., Okuno, H., Redeker, J. C., Sanchez, J., Sasaki, M., Sasao, N., Sato, T., Sato, K., Sato, Y., Shimizu, N., Shimogawa, T., Shinkawa, T., Shinohara, S., Shiomi, K., Shiraishi, R., Su, S., Sugiyama, Y., Suzuki, S., Tajima, Y., Taylor, M., Tecchio, M., Togawa, M., Toyoda, T., Tung, Y. -C., Vuong, Q. H., Wah, Y. W., Watanabe, H., Yamanaka, T., Yoshida, H. Y., and Zaidenberg, L.

Subjects
High Energy Physics - Experiment
Abstract

The rare decay $K_L \!\to\! \pi^0 \nu \overline{\nu}$ was studied with the dataset taken at the J-PARC KOTO experiment in 2016, 2017, and 2018. With a single event sensitivity of $( 7.20 \pm 0.05_{\rm stat} \pm 0.66_{\rm syst} ) \times 10^{-10}$, three candidate events were observed in the signal region. After unveiling them, contaminations from $K^{\pm}$ and scattered $K_L$ decays were studied, and the total number of background events was estimated to be $1.22 \pm 0.26$. We conclude that the number of observed events is statistically consistent with the background expectation. For this dataset, we set an upper limit of $4.9 \times 10^{-9}$ on the branching fraction of $K_L \!\to\! \pi^0 \nu \overline{\nu}$ at the 90% confidence level., Comment: 6 pages, 5 figures; published version, no change in the results. Fig. 2 and Fig. 4 were revised. In Fig. 5, the plot of the $P_{t}$ versus ${Z_{\mathrm{vtx}}}$ of the beam-halo $K_L\!\to\!2\gamma$ background events was added as Fig. 5 (b)

Published
2020
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6. First Search for the $K_L \to \pi^0 \gamma$ Decay

Author

Ahn, J. K., Beckford, B., Campbell, M., Chen, S. H., Choi, J. M., Comfort, J., Dona, K., Farrington, M. S., Hara, N., Haraguchi, H., Hsiung, Y. B., Hutcheson, M., Inagaki, T., Isoe, M., Kamiji, I., Kim, E. J., Kim, J. L., Kim, H. M., Komatsubara, T. K., Kotera, K., Lee, J. W., Lim, G. Y., Lin, C., Lin, Q. S., Luo, Y., Mari, T., Matsumura, T., Mcfarland, D., Miyazaki, K., Murayama, R., Nakagiri, K., Nanjo, H., Nishimiya, H., Noichi, Y., Nomura, T., Nunes, T., Ohsugi, M., Okuno, H., Redeker, J. C., Sato, K., Sato, T., Sato, Y., Shimizu, N., Shimogawa, T., Shinkawa, T., Shinohara, S., Shiomi, K., Shiraishi, R., Su, S., Sugiyama, Y., Suzuki, S., Tajima, Y., Taylor, M., Tecchio, M., Togawa, M., Toyoda, T., Tung, Y. C., Vuong, Q. H., Wah, Y. W., Watanabe, H., Yamanaka, T., and Yoshida, H. Y.

Subjects
High Energy Physics - Experiment
Abstract

We report the first search for the $K_L \to \pi^0 \gamma$ decay, which is forbidden by Lorentz invariance, using the data from 2016 to 2018 at the J-PARC KOTO experiment. With a single event sensitivity of $(7.1\pm 0.3_{\rm stat.} \pm 1.6_{\rm syst.})\times 10^{-8}$, no candidate event was observed in the signal region. The upper limit on the branching fraction was set to be $1.7\times 10^{-7}$ at the 90\% confidence level.

Published
2020
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7. Study of the KL→π0νν¯ Decay at the J-PARC KOTO Experiment

Author

Ahn, JK, Beckford, B, Campbell, M, Chen, SH, Comfort, J, Dona, K, Farrington, MS, Hanai, K, Hara, N, Haraguchi, H, Hsiung, YB, Hutcheson, M, Inagaki, T, Isoe, M, Kamiji, I, Kato, T, Kim, EJ, Kim, JL, Kim, HM, Komatsubara, TK, Kotera, K, Lee, SK, Lee, JW, Lim, GY, Lin, QS, Lin, C, Luo, Y, Mari, T, Masuda, T, Matsumura, T, Mcfarland, D, McNeal, N, Miyazaki, K, Murayama, R, Nakagiri, K, Nanjo, H, Nishimiya, H, Noichi, Y, Nomura, T, Nunes, T, Ohsugi, M, Okuno, H, Redeker, JC, Sanchez, J, Sasaki, M, Sasao, N, Sato, T, Sato, K, Sato, Y, Shimizu, N, Shimogawa, T, Shinkawa, T, Shinohara, S, Shiomi, K, Shiraishi, R, Su, S, Sugiyama, Y, Suzuki, S, Tajima, Y, Taylor, M, Tecchio, M, Togawa, M, Toyoda, T, Tung, Y-C, Vuong, QH, Wah, YW, Watanabe, H, Yamanaka, T, Yoshida, HY, and Zaidenberg, L

Subjects
Particle and High Energy Physics, Physical Sciences, KOTO Collaboration, hep-ex, Mathematical Sciences, Engineering, General Physics, Mathematical sciences, Physical sciences
Abstract

The rare decay K_{L}→π^{0}νν[over ¯] was studied with the dataset taken at the J-PARC KOTO experiment in 2016, 2017, and 2018. With a single event sensitivity of (7.20±0.05_{stat}±0.66_{syst})×10^{-10}, three candidate events were observed in the signal region. After unveiling them, contaminations from K^{±} and scattered K_{L} decays were studied, and the total number of background events was estimated to be 1.22±0.26. We conclude that the number of observed events is statistically consistent with the background expectation. For this dataset, we set an upper limit of 4.9×10^{-9} on the branching fraction of K_{L}→π^{0}νν[over ¯] at the 90% confidence level.

Published
2021

8. Search for $K_L \!\to\! \pi^0 \nu \overline{\nu}$ and $K_L \!\to\! \pi^0 X^0$ Decays at the J-PARC KOTO Experiment

Author

KOTO Collaboration, Ahn, J. K., Beckford, B., Beechert, J., Bryant, K., Campbell, M., Chen, S. H., Comfort, J., Dona, K., Hara, N., Haraguchi, H., Hsiung, Y. B., Hutcheson, M., Inagaki, T., Kamiji, I., Kawasaki, N., Kim, E. J., Kim, J. L., Kim, Y. J., Ko, J. W., Komatsubara, T. K., Kotera, K., Kurilin, A. S., Lee, J. W., Lim, G. Y., Lin, C., Lin, Q., Luo, Y., Ma, J., Maeda, Y., Mari, T., Masuda, T., Matsumura, T., Mcfarland, D., McNeal, N., Micallef, J., Miyazaki, K., Murayama, R., Naito, D., Nakagiri, K., Nanjo, H., Nishimiya, H., Nomura, T., Ohsugi, M., Okuno, H., Sasaki, M., Sasao, N., Sato, K., Sato, T., Sato, Y., Schamis, H., Seki, S., Shimizu, N., Shimogawa, T., Shinkawa, T., Shinohara, S., Shiomi, K., Su, S., Sugiyama, Y., Suzuki, S., Tajima, Y., Taylor, M., Tecchio, M., Togawa, M., Tung, Y. C., Wah, Y. W., Watanabe, H., Woo, J. K., Yamanaka, T., and Yoshida, H. Y.

Subjects
High Energy Physics - Experiment
Abstract

A search for the rare decay $K_L \!\to\! \pi^0 \nu \overline{\nu}$ was performed. With the data collected in 2015, corresponding to $2.2 \times 10^{19}$ protons on target, a single event sensitivity of $( 1.30 \pm 0.01_{\rm stat} \pm 0.14_{\rm syst} ) \times 10^{-9}$ was achieved and no candidate events were observed. We set an upper limit of $3.0 \times 10^{-9}$ for the branching fraction of $K_L \!\to\! \pi^0 \nu \overline{\nu}$ at the 90% confidence level (C.L.), which improved the previous limit by almost an order of magnitude. An upper limit for $K_L \!\to\! \pi^0 X^0$ was also set as $2.4 \times 10^{-9}$ at the 90% C.L., where $X^0$ is an invisible boson with a mass of $135~{\rm MeV}/c^2$., Comment: 6 pages, 4 figures; published version, no change in the results. Fig. 1, Fig. 2, and Fig. 3 were revised, and Fig. 4 presenting the $K_L \!\to\! \pi^0 X^0$ limit as a function of the $X^0$ mass was added

Published
2018
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9. A new search for the $K_{L} \to \pi^0 \nu \overline{\nu}$ and $K_{L} \to \pi^{0} X^{0}$ decays

Author

Ahn, J. K., Baek, K. Y., Banno, S., Beckford, B., Brubaker, B., Cai, T., Campbell, M., Carruth, C., Chen, S. H., Chu, S., Comfort, J., Duh, Y. T., Furukawa, T., Haraguchi, H., Hineno, T., Hsiung, Y. B., Hutcheson, M., Inagaki, T., Isoe, M., Iwai, E., Kamibayashi, T., Kamiji, I., Kawasaki, N., Kim, E. J., Kim, Y. J., Ko, J. W., Komatsubara, T. K., Kurilin, A. S., Lee, G. H., Lee, H. S., Lee, J. W., Lee, S. K., Lim, G. Y., Lin, C., Ma, J., Maeda, Y., Masuda, T., Matsumura, T., Mcfarland, D., Micallef, J., Miyazaki, K., Morgan, K., Murayama, R., Naito, D., Nakagiri, K., Nakajima, Y., Nakaya, Y., Nanjo, H., Nomura, T., Odani, Y., Ogata, R., Okuno, H., Ota, T., Ri, Y. D., Sasaki, M., Sasao, N., Sato, K., Sato, T., Seki, S., Shimogawa, T., Shinkawa, T., Shinohara, S., Shiomi, K., Son, J. S., Stevens, J., Su, S., Sugiyama, Y., Suzuki, S., Tajima, Y., Takahashi, G., Takashima, Y., Tecchio, M., Teo, I., Togawa, M., Toyoda, T., Tung, Y. C., Usuki, T., Wah, Y. W., Watanabe, H., Whallon, N., Woo, J. K., Xu, J., Yamaga, M., Yamamoto, S., Yamanaka, T., Yamauchi, H., Yanagida, Y., Yokota, H., Yoshida, H. Y., and Yoshimoto, H.

Subjects
High Energy Physics - Experiment
Abstract

We searched for the $CP$-violating rare decay of neutral kaon, $K_{L} \to \pi^0 \nu \overline{\nu}$, in data from the first 100 hours of physics running in 2013 of the J-PARC KOTO experiment. One candidate event was observed while $0.34\pm0.16$ background events were expected. We set an upper limit of $5.1\times10^{-8}$ for the branching fraction at the 90\% confidence level (C.L.). An upper limit of $3.7\times10^{-8}$ at the 90\% C.L. for the $K_{L} \to \pi^{0} X^{0}$decay was also set for the first time, where $X^{0}$ is an invisible particle with a mass of 135 MeV/$c^{2}$., Comment: 11 pages, 5 figures, to be published in PTEP

Published
2016
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10. Interference effect between $\phi$ and $\Lambda(1520)$ production channels in the $\gamma p \rightarrow K^+K^-p$ reaction near threshold

Author

Ryu, S. Y., Ahn, J. K., Nakano, T., Ahn, D. S., Ajimura, S., Akimune, H., Asano, Y., Chang, W. C., Chen, J. Y., Date, S., Ejiri, H., Fujimura, H., Fujiwara, M., Fukui, S., Hasegawa, S., Hicks, K., Horie, K., Hotta, T., Hwang, S. H., Imai, K., Ishikawa, T., Iwata, T., Kato, Y., Kawai, H., Kino, K., Kohri, H., Kon, Y., Kumagai, N., Lin, P. J., Maeda, Y., Makino, S., Matsuda, T., Matsuoka, N., Mibe, T., Miyabe, M., Miyachi, M., Morino, Y., Muramatsu, N., Murayama, R., Nakatsugawa, Y., Nam, S. i., Niiyama, M., Nomachi, M., Ohashi, Y., Ohkuma, H., Ohta, T., Ooba, T., Oshuev, D. S., Parker, J. D., Rangacharyulu, C., Sakaguchi, A., Sawada, T., Shagin, P. M., Shiino, Y., Shimizu, H., Strokovsky, E. A., Sugaya, Y., Sumihama, M., Tokiyasu, A. O., Toi, Y., Toyokawa, H., Tsunemi, T., Uchida, M., Ungaro, M., Wakai, A., Wang, C. W., Wang, S. C., Yonehara, K., Yorita, T., Yoshimura, M., Yosoi, M., and Zegers, R. G. T.

Subjects
Nuclear Experiment
Abstract

The $\phi$-$\Lambda(1520)$ interference effect in the $\gamma p\to K^+K^-p$ reaction has been measured for the first time in the energy range from 1.673 to 2.173 GeV. The relative phases between $\phi$ and $\Lambda(1520)$ production amplitudes were obtained in the kinematic region where the two resonances overlap. The measurement results support strong constructive interference when $K^+K^-$ pairs are observed at forward angles, but destructive interference for proton emission at forward angles. Furthermore, the observed interference effect does not account for the $\sqrt{s}=2.1$ GeV bump structure in forward differential cross sections for $\phi$ photoproduction. This fact suggests possible exotic structures such as a hidden-strangeness pentaquark state, a new Pomeron exchange and rescattering processes via other hyperon states.

Published
2016
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11. Pulse shape discrimination of photons and neutrons in the energy range of 0.1 – 2 GeV with the KOTO un-doped CsI calorimeter

Author

Sugiyama, Y., Ahn, J.K., Banno, S., Beckford, B., Campbell, M., Chen, S.H., Comfort, J., Duh, Y.T., Hineno, T., Hsiung, Y.B., Hutcheson, M., Iwai, E., Kamiji, I., Kawasaki, N., Kim, E.J., Kim, J.L., Kim, Y.J., Ko, J.W., Komatsubara, T.K., Kurilin, A.S., Lee, J.W., Lee, S.K., Lim, G.Y., Lin, C., Lin, Q., Luo, Y., Ma, J., Maeda, Y., Masuda, T., Matsumura, T., Mcfarland, D., Murayama, R., Naito, D., Nakagiri, K., Nakaya, Y., Nanjo, H., Nomura, T., Odani, Y., Redeker, J.C., Ri, Y.D., Sasao, N., Sato, K., Seki, S., Shimogawa, T., Shinkawa, T., Shinohara, S., Shiomi, K., Su, S., Suzuki, S., Tajima, Y., Takahashi, G., Takashima, Y., Tecchio, M., Togawa, M., Tung, Y.C., Wah, Y.W., Watanabe, H., Whallon, N., Woo, J.K., Xu, J., Yamanaka, T., Yanagida, Y., Yoshida, H.Y., and Yoshimoto, H.

Published
2021
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12. Long-lived neutral-kaon flux measurement for the KOTO experiment

Author

Masuda, T., Ahn, J. K., Banno, S., Campbell, M., Comfort, J., Duh, Y. T., Hineno, T., Hsiung, Y. B., Inagaki, T., Iwai, E., Kawasaki, N., Kim, E. J., Kim, Y. J., Ko, J. W., Komatsubara, T. K., Kurilin, A. S., Lee, G. H., Lee, J. W., Lee, S. K., Lim, G. Y., Ma, J., MacFarland, D., Maeda, Y., Matsumura, T., Murayama, R., Naito, D., Nakaya, Y., Nanjo, H., Nomura, T., Odani, Y., Okuno, H., Ri, Y. D., Sasao, N., Sato, K., Sato, T., Seki, S., Shimogawa, T., Shinkawa, T., Shiomi, K., Son, J. S., Sugiyama, Y., Suzuki, S., Tajima, Y., Takahashi, G., Takashima, Y., Tecchio, M., Togawa, M., Toyoda, T., Tung, Y. C., Wah, Y. W., Watanabe, H., Woo, J. K., Xu, J., Yamanaka, T., Yanagida, Y., Yoshida, H. Y., and Yoshimoto, H.

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

The KOTO ($K^0$ at Tokai) experiment aims to observe the CP-violating rare decay $K_L \rightarrow \pi^0 \nu \bar{\nu}$ by using a long-lived neutral-kaon beam produced by the 30 GeV proton beam at the Japan Proton Accelerator Research Complex. The $K_L$ flux is an essential parameter for the measurement of the branching fraction. Three $K_L$ neutral decay modes, $K_L \rightarrow 3\pi^0$, $K_L \rightarrow 2\pi^0$, and $K_L \rightarrow 2\gamma$ were used to measure the $K_L$ flux in the beam line in the 2013 KOTO engineering run. A Monte Carlo simulation was used to estimate the detector acceptance for these decays. Agreement was found between the simulation model and the experimental data, and the remaining systematic uncertainty was estimated at the 1.4\% level. The $K_L$ flux was measured as $(4.183 \pm 0.017_{\mathrm{stat.}} \pm 0.059_{\mathrm{sys.}}) \times 10^7$ $K_L$ per $2\times 10^{14}$ protons on a 66-mm-long Au target., Comment: 27 pages, 16 figures. To be appeared in Progress of Theoretical and Experimental Physics

Published
2015
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13. CsI calorimeter for the J-PARC KOTO experiment

Author

Sato, K., Lee, J.W., Banno, S., Campbell, M., Comfort, J., Furukawa, T., Iwai, E., Kawasaki, N., Komatsubara, T.K., Lim, G.Y., Maeda, Y., Masuda, T., Matsumura, T., Mcfarland, D., Murayama, R., Naito, D., Nakaya, Y., Nanjo, H., Nomura, T., Odani, Y., Ota, T., Ri, Y.D., Sasaki, M., Sasao, N., Seki, S., Shimogawa, T., Shinkawa, T., Shiomi, K., Sugiyama, Y., Suzuki, S., Tajima, Y., Tecchio, M., Togawa, M., Yamanaka, T., Yanagida, Y., Yokota, H., Yoshimoto, H., Wah, Y.W., Watanabe, H., and Xu, J.

Published
2020
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15. Precise lifetime measurement of Λ4H hypernucleus using in-flight 4He(K−,π0)Λ4H reaction

Author

Akaishi, T., primary, Asano, H., additional, Chen, X., additional, Clozza, A., additional, Curceanu, C., additional, Del Grande, R., additional, Guaraldo, C., additional, Han, C., additional, Hashimoto, T., additional, Iliescu, M., additional, Inoue, K., additional, Ishimoto, S., additional, Itahashi, K., additional, Iwasaki, M., additional, Ma, Y., additional, Miliucci, M., additional, Murayama, R., additional, Noumi, H., additional, Ohnishi, H., additional, Okada, S., additional, Outa, H., additional, Piscicchia, K., additional, Sakaguchi, A., additional, Sakuma, F., additional, Sato, M., additional, Scordo, A., additional, Shirotori, K., additional, Sirghi, D., additional, Sirghi, F., additional, Suzuki, S., additional, Tanida, K., additional, Toda, T., additional, Tokuda, M., additional, Yamaga, T., additional, Yuan, X., additional, Zhang, P., additional, Zhang, Y., additional, and Zhang, H., additional

Published
2023
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16. Search for $K^-pp$ bound state via $\gamma d \rightarrow K^+ \pi^-X$ reaction at $E_\gamma=1.5-2.4$ GeV

Author

Tokiyasu, A. O., Niiyama, M., Parker, J. D., Ahn, D. S., Ahn, J. K., Ajimura, S., Akimune, H., Asano, Y., Chang, W. C., Chen, J. Y., Daté, S., Ejiri, H., Fujimura, H., Fujiwara, M., Fukui, S., Hasegawa, S., Hicks, K., Horie, K., Hotta, T., Hwang, S. H., Imai, K., Ishikawa, T., Iwata, T., Kato, Y., Kawai, H., Kino, K., Kohri, H., Kon, Y., Kumagai, N., Lin, D. L., Maeda, Y., Makino, S., Matsuda, T., Matsumura, T., Matsuoka, N., Mibe, T., Miyabe, M., Miyachi, M., Muramatsu, N., Murayama, R., Nakano, T., Nakatsugawa, Y., Nomachi, M., Ohashi, Y., Ohkuma, H., Ohta, T., Ooba, T., Oshuev, D. S., Rangacharyulu, C., Ryu, S. Y., Sakaguchi, A., Sawada, T., Shagin, P. M., Shiino, Y., Shimizu, H., Strokovsky, E. A., Sugaya, Y., Sumihama, M., Tang, J. L., Toi, Y., Toyokawa, H., Tsunemi, T., Uchida, M., Ungaro, M., Wakai, A., Wang, C. W., Wang, S. C., Yonehara, K., Yorita, T., Yoshimura, M., Yosoi, M., and Zegers, R. G. T.

Subjects
Nuclear Experiment
Abstract

A search for $K^-pp$ bound state (the lightest kaonic nucleus) has been performed using the $\gamma d \rightarrow K^+ \pi^- \rm{X}$ reaction at E$_\gamma$=1.5-2.4 GeV at LEPS/SPring-8. The differential cross section of $K^+ \pi^-$ photo-production off deuterium has been measured for the first time in this energy region, and a bump structure was searched for in the inclusive missing mass spectrum. A statistically significant bump structure was not observed in the region from 2.22 to 2.36 GeV/$c^2$, and the upper limits of the differential cross section for the $K^-pp$ bound state production were determined to be 0.1$-$0.7 $\mu$ b (95$%$ confidence level) for a set of assumed binding energy and width values.

Published
2013
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17. Pole position of Λ(1405) measured in d(K−,n)πΣ reactions

Author

Aikawa, S., primary, Ajimura, S., additional, Akaishi, T., additional, Asano, H., additional, Beer, G., additional, Berucci, C., additional, Bragadireanu, M., additional, Buehler, P., additional, Busso, L., additional, Cargnelli, M., additional, Choi, S., additional, Curceanu, C., additional, Enomoto, S., additional, Fujioka, H., additional, Fujiwara, Y., additional, Fukuda, T., additional, Guaraldo, C., additional, Hashimoto, T., additional, Hayano, R.S., additional, Hiraiwa, T., additional, Iio, M., additional, Iliescu, M., additional, Inoue, K., additional, Ishiguro, Y., additional, Ishimoto, S., additional, Ishikawa, T., additional, Itahashi, K., additional, Iwai, M., additional, Iwasaki, M., additional, Kanno, K., additional, Kato, K., additional, Kato, Y., additional, Kawasaki, S., additional, Kienle, P., additional, Komatsu, Y., additional, Kou, H., additional, Ma, Y., additional, Marton, J., additional, Matsuda, Y., additional, Mizoi, Y., additional, Morra, O., additional, Murayama, R., additional, Nagae, T., additional, Noumi, H., additional, Ohnishi, H., additional, Okada, S., additional, Omar, Z., additional, Outa, H., additional, Piscicchia, K., additional, Sada, Y., additional, Sakaguchi, A., additional, Sakuma, F., additional, Sato, M., additional, Scordo, A., additional, Sekimoto, M., additional, Shi, H., additional, Shirotori, K., additional, Sirghi, D., additional, Sirghi, F., additional, Suzuki, K., additional, Suzuki, S., additional, Suzuki, T., additional, Tanida, K., additional, Tatsuno, H., additional, Tokiyasu, A.O., additional, Tokuda, M., additional, Tomono, D., additional, Toyoda, A., additional, Tsukada, K., additional, Vazquez-Doce, O., additional, Widmann, E., additional, Yamaga, T., additional, Yamazaki, T., additional, Yim, H., additional, Zhang, Q., additional, and Zmeskal, J., additional

Published
2023
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18. Precise lifetime measurement of $^4_\Lambda$H hypernucleus using a novel production method

Author

Akaishi, T., Asano, H., Chen, X., Clozza, A., Curceanu, C., Del Grande, R., Guaraldo, C., Han, C., Hashimoto, T., Iliescu, M., Inoue, K., Ishimoto, S., Itahashi, K., Iwasaki, M., Ma, Y., Miliucci, M., Murayama, R., Noumi, H., Ohnishi, H., Okada, S., Outa, H., Piscicchia, K., Sakaguchi, A., Sakuma, F., Sato, M., Scordo, A., Shirotori, K., Sirghi, D., Sirghi, F., Suzuki, S., Tanida, K., Toda, T., Tokuda, M., Yamaga, T., Yuan, X., Zhang, P., Zhang, Y., and Zhang, H.

Subjects
Nuclear Experiment
Abstract

We present a new measurement of the $^4_\Lambda$H hypernuclear lifetime using a novel production reaction, $K^-$ + $^4$He $\rightarrow$ $^4_\Lambda\ $H + $\pi^0$, at the J-PARC hadron facility. We demonstrate, for the first time, the effective selection of the hypernuclear bound state using only t\ he $\gamma$-ray energy decayed from $\pi^0$. This opens the possibility for a systematic study of isospin partner hypernuclei through comparison with data from ($K^-$, $\pi^-$) reaction. As the first application of this method, our result for the $^4_\Lambda$H lifetime, $\tau(^4_\Lambda \mathrm{H}\ ) = 206 \pm 8 (\mathrm{stat.}) \pm 12 (\mathrm{syst.})\ \mathrm{ps}$, is one of the most precise measurements to date. We are also preparing to measu\ re the lifetime of the hypertriton ($^3_\Lambda$H) using the same setup in the near future.

Published
2023

19. Status of J-PARC E73 experiment: first direct Hypertriton lifetime measurement with 3He(K--, π 0 ) 3Λ H reaction

Author

Akaishi, T., primary, Sakaguchi, A., additional, Toda, T., additional, Tokuda, M., additional, Asano, H., additional, Itahashi, K., additional, Iwasaki, M., additional, Ma, Yue, additional, Murayama, R., additional, Outa, H., additional, Sakuma, F., additional, Yamaga, T., additional, Clozza, A., additional, Curceanu, C., additional, Del Grande, R., additional, Guaraldo, C., additional, Iliescu, M., additional, Miliucci, M., additional, Piscicchia, K., additional, Scordo, A., additional, Sirghi, D., additional, Sirghi, F., additional, Han, C., additional, Yuan, X., additional, Zhang, P., additional, Zhang, Y., additional, Hashimoto, T., additional, Tanida, K., additional, Ishimoto, S., additional, Suzuki, S., additional, Sato, M., additional, Inoue, K., additional, Noumi, H., additional, Shirotori, K., additional, Ohnishi, H., additional, Okada, S., additional, and Zhang, H., additional

Published
2022
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20. Pole position of $Λ(1405)$ measured in $d(K^-,n)πΣ$ reactions

Author

PARC E31 Collaboration, Aikawa, S., Ajimura, S., Akaishi, T., Asano, H., Beer, G., Berucci, C., Bragadireanu, M., Buehler, P., Busso, L., Cargnelli, M., Choi, S., Curceanu, C., Enomoto, S., Fujioka, H., Fujiwara, Y., Fukuda, T., Guaraldo, C., Hashimoto, T., Hayano, R. S., Hiraiwa, T., Iio, M., Iliescu, M., Inoue, K., Ishiguro, Y., Ishimoto, S., Ishikawa, T., Itahashi, K., Iwai, M., Iwasaki, M., Kanno, K., Kato, K., Kato, Y., Kawasaki, S., Kienle, P., Komatsu, Y., Kou, H., Ma, Y., Marton, J., Matsuda, Y., Mizoi, Y., Morra, O., Murayama, R., Nagae, T., Noumi, H., Ohnishi, H., Okada, S., Omar, Z., Outa, H., Piscicchia, K., Sada, Y., Sakaguchi, A., Sakuma, F., Sato, M., Scordo, A., Sekimoto, M., Shi, H., Shirotori, K., Sirghi, D., Sirghi, F., Suzuki, K., Suzuki, S., Suzuki, T., Tanida, K., Tatsuno, H., Tokiyasu, A. O., Tokuda, M., Tomono, D., Toyoda, A., Tsukada, K., Vazquez-Doce, O., Widmann, E., Yamaga, T., Yamazaki, T., Yim, H., Zhang, Q., and Zmeskal, J.

Subjects
FOS: Physical sciences, Nuclear Experiment (nucl-ex)
Abstract

We measured a set of $π^\pmΣ^\mp$, $π^0Σ^0$, and $π^-Σ^0$ invariant mass spectra below and above the $\bar{K}N$ mass threshold in $K^-$-induced reactions on deuteron. We deduced the $S$-wave $\bar{K}N\rightarrowπΣ$ and $\bar{K}N\rightarrow\bar{K}N$ scattering amplitudes in the isospin 0 channel in the framework of a $\bar{K}N$ and $πΣ$ coupled channel. We find that a resonance pole corresponding to $Λ(1405)$ is located at 1417.7$^{+6.0}_{-7.4}$(fitting errors)$^{+1.1}_{-1.0}$(systematic errors) + $[-26.1^{+6.0}_{-7.9}$(fitting errors)$^{+1.7}_{-2.0}$(systematic errors)]$i$ MeV/$c^2$, closer to the $\bar{K}N$ mass threshold than the value determined by the Particle Data Group., 8 pages, 5 figures

Published
2022
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21. Recent Results and Future Prospects of Kaonic Nuclei at J-PARC

Author

Sakuma, F., primary, Ajimura, S., additional, Akaishi, T., additional, Asano, H., additional, Bazzi, M., additional, Beer, G., additional, Bhang, H., additional, Bragadireanu, M., additional, Buehler, P., additional, Busso, L., additional, Cargnelli, M., additional, Choi, S., additional, Clozza, A., additional, Curceanu, C., additional, Enomoto, S., additional, Fujioka, H., additional, Fujiwara, Y., additional, Fukuda, T., additional, Guaraldo, C., additional, Hashimoto, T., additional, Hayano, R. S., additional, Hiraiwa, T., additional, Iio, M., additional, Iliescu, M., additional, Inoue, K., additional, Ishiguro, Y., additional, Ishikawa, T., additional, Ishimoto, S., additional, Itahashi, K., additional, Iwasaki, M., additional, Iwai, M., additional, Kanno, K., additional, Kato, K., additional, Kato, Y., additional, Kawasaki, S., additional, Kienle, P., additional, Kou, H., additional, Ma, Y., additional, Marton, J., additional, Matsuda, Y., additional, Miliucci, M., additional, Mizoi, Y., additional, Morra, O., additional, Murayama, R., additional, Nagae, T., additional, Noumi, H., additional, Ohnishi, H., additional, Okada, S., additional, Outa, H., additional, Ozawa, K., additional, Piscicchia, K., additional, Sada, Y., additional, Sakaguchi, A., additional, Sato, M., additional, Scordo, A., additional, Sekimoto, M., additional, Shi, H., additional, Shirotori, K., additional, Simon, M., additional, Sirghi, D., additional, Sirghi, F., additional, Suzuki, S., additional, Suzuki, T., additional, Tanida, K., additional, Tatsuno, H., additional, Tokuda, M., additional, Tomono, D., additional, Toyoda, A., additional, Tsukada, K., additional, Doce, O. Vázquez, additional, Widmann, E., additional, Yamaga, T., additional, Yamazaki, T., additional, Yoshida, C., additional, Zhang, Q., additional, and Zmeskal, J., additional

Published
2021
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22. Muon spin motion at the crossover regime between Gaussian and Lorentzian distribution of magnetic fields

Author

Umar, MD, Ishida, K, Murayama, R, Puspita Sari, D, Widyaiswari, U, Fronzi, M, Rozak, H, Zaharim, WN, Watanabe, I, and Iwasaki, M

Subjects
01 Mathematical Sciences, 02 Physical Sciences
Abstract

The muon spin relaxation method is a powerful microscopic tool for probing the electronic states of materials by observing local magnetic field distributions on the muon. It often happens that a distribution of local magnetic fields shows an intermediate state between Gaussian and Lorentzian shapes. In order to generally describe these intermediate field distributions, we considered the convolution of two isotropic distributions in three dimensions and derived exact muon-spin relaxation functions which can be applied to all crossover regimes between Gaussian and Lorentzian.

Published
2021

23. A trigger system for measurements of proton-induced rare hadronic reactions around [formula omitted]

Author

Minami, S., Itabashi, T., Ajimura, S., Fukuda, T., Hayakawa, H., Hayakawa, T., Imoto, W., Kanie, T., Khanam, F., Kishimoto, T., Kohri, H., Matsuoka, K., Mitoma, Y., Miyake, Y.S., Mori, T., Morikubo, K., Murayama, R., Nagao, T., Noumi, H., Numata, T., Ogaito, T., Saha, P.K., Sakaguchi, A., Sekimoto, M., Shimizu, Y., Sugita, K., Sumihama, M., Tamura, K., Terai, K., and Wakae, K.

Published
2008
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24. Study of the $K_L \!\to\! ��^0 ��\overline��$ Decay at the J-PARC KOTO Experiment

Author

KOTO Collaboration, Ahn, J. K., Beckford, B., Campbell, M., Chen, S. H., Comfort, J., Dona, K., Farrington, M. S., Hanai, K., Hara, N., Haraguchi, H., Hsiung, Y. B., Hutcheson, M., Inagaki, T., Isoe, M., Kamiji, I., Kato, T., Kim, E. J., Kim, J. L., Kim, H. M., Komatsubara, T. K., Kotera, K., Lee, S. K., Lee, J. W., Lim, G. Y., Lin, Q. S., Lin, C., Luo, Y., Mari, T., Masuda, T., Matsumura, T., Mcfarland, D., McNeal, N., Miyazaki, K., Murayama, R., Nakagiri, K., Nanjo, H., Nishimiya, H., Noichi, Y., Nomura, T., Nunes, T., Ohsugi, M., Okuno, H., Redeker, J. C., Sanchez, J., Sasaki, M., Sasao, N., Sato, T., Sato, K., Sato, Y., Shimizu, N., Shimogawa, T., Shinkawa, T., Shinohara, S., Shiomi, K., Shiraishi, R., Su, S., Sugiyama, Y., Suzuki, S., Tajima, Y., Taylor, M., Tecchio, M., Togawa, M., Toyoda, T., Tung, Y. -C., Vuong, Q. H., Wah, Y. W., Watanabe, H., Yamanaka, T., Yoshida, H. Y., and Zaidenberg, L.

Subjects
High Energy Physics - Experiment (hep-ex), FOS: Physical sciences
Abstract

The rare decay $K_L \!\to\! ��^0 ��\overline��$ was studied with the dataset taken at the J-PARC KOTO experiment in 2016, 2017, and 2018. With a single event sensitivity of $( 7.20 \pm 0.05_{\rm stat} \pm 0.66_{\rm syst} ) \times 10^{-10}$, three candidate events were observed in the signal region. After unveiling them, contaminations from $K^{\pm}$ and scattered $K_L$ decays were studied, and the total number of background events was estimated to be $1.22 \pm 0.26$. We conclude that the number of observed events is statistically consistent with the background expectation. For this dataset, we set an upper limit of $4.9 \times 10^{-9}$ on the branching fraction of $K_L \!\to\! ��^0 ��\overline��$ at the 90% confidence level., 6 pages, 5 figures; published version, no change in the results. Fig. 2 and Fig. 4 were revised. In Fig. 5, the plot of the $P_{t}$ versus ${Z_{\mathrm{vtx}}}$ of the beam-halo $K_L\!\to\!2\gamma$ background events was added as Fig. 5 (b)

Published
2020
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25. First Search for the $K_L \to ��^0 ��$ Decay

Author

Ahn, J. K., Beckford, B., Campbell, M., Chen, S. H., Choi, J. M., Comfort, J., Dona, K., Farrington, M. S., Hara, N., Haraguchi, H., Hsiung, Y. B., Hutcheson, M., Inagaki, T., Isoe, M., Kamiji, I., Kim, E. J., Kim, J. L., Kim, H. M., Komatsubara, T. K., Kotera, K., Lee, J. W., Lim, G. Y., Lin, C., Lin, Q. S., Luo, Y., Mari, T., Matsumura, T., Mcfarland, D., Miyazaki, K., Murayama, R., Nakagiri, K., Nanjo, H., Nishimiya, H., Noichi, Y., Nomura, T., Nunes, T., Ohsugi, M., Okuno, H., Redeker, J. C., Sato, K., Sato, T., Sato, Y., Shimizu, N., Shimogawa, T., Shinkawa, T., Shinohara, S., Shiomi, K., Shiraishi, R., Su, S., Sugiyama, Y., Suzuki, S., Tajima, Y., Taylor, M., Tecchio, M., Togawa, M., Toyoda, T., Tung, Y. C., Vuong, Q. H., Wah, Y. W., Watanabe, H., Yamanaka, T., and Yoshida, H. Y.

Subjects
High Energy Physics - Experiment (hep-ex), FOS: Physical sciences
Abstract

We report the first search for the $K_L \to ��^0 ��$ decay, which is forbidden by Lorentz invariance, using the data from 2016 to 2018 at the J-PARC KOTO experiment. With a single event sensitivity of $(7.1\pm 0.3_{\rm stat.} \pm 1.6_{\rm syst.})\times 10^{-8}$, no candidate event was observed in the signal region. The upper limit on the branching fraction was set to be $1.7\times 10^{-7}$ at the 90\% confidence level.

Published
2020
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27. A new cylindrical photon-veto detector for the KL→π0νν¯ experiment

Author

Murayama, R., primary, Togawa, M., additional, Ahn, J.K., additional, Comfort, J., additional, Inagaki, T., additional, Isoe, M., additional, Kamiji, I., additional, Kim, E.J., additional, Kim, J.L., additional, Komatsubara, T.K., additional, Lim, G.Y., additional, Matsumura, T., additional, Miyazaki, K., additional, Nanjo, H., additional, Nomura, T., additional, Okuno, H., additional, Pod, E., additional, Sato, T., additional, Shiomi, K., additional, Tajima, Y., additional, Toyoda, T., additional, Wah, Y.W., additional, Watanabe, H., additional, and Yamanaka, T., additional

Published
2020
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29. Search for <math><mrow><msub><mrow><mi>K</mi></mrow><mrow><mi>L</mi></mrow></msub><mo>→</mo><msup><mrow><mi>π</mi></mrow><mrow><mn>0</mn></mrow></msup><mi>ν</mi><mover><mrow><mi>ν</mi></mrow><mrow><mo>¯</mo></mrow></mover></mrow></math> and <math><msub><mi>K</mi><mi>L</mi></msub><mo>→</mo><msup><mi>π</mi><mn>0</mn></msup><msup><mi>X</mi><mn>0</mn></msup></math> Decays at the J-PARC KOTO Experiment

Author

Ahn, J. K., Beckford, B., Beechert, J., Bryant, K., Campbell, M., Chen, S. H., Comfort, J., Dona, K., Hara, N., Haraguchi, H., Hsiung, Y. B., Hutcheson, M., Inagaki, T., Kamiji, I., Kawasaki, N., Kim, E. J., Kim, J. L., Kim, Y. J., Ko, J. W., Komatsubara, T. K., Kotera, K., Kurilin, A. S., Lee, J. W., Lim, G. Y., Lin, C., Lin, Q., Luo, Y., Ma, J., Maeda, Y., Mari, T., Masuda, T., Matsumura, T., Mcfarland, D., McNeal, N., Micallef, J., Miyazaki, K., Murayama, R., Naito, D., Nakagiri, K., Nanjo, H., Nishimiya, H., Nomura, T., Ohsugi, M., Okuno, H., Sasaki, M., Sasao, N., Sato, K., Sato, T., Sato, Y., Schamis, H., Seki, S., Shimizu, N., Shimogawa, T., Shinkawa, T., Shinohara, S., Shiomi, K., Su, S., Sugiyama, Y., Suzuki, S., Tajima, Y., Taylor, M., Tecchio, M., Togawa, M., Tung, Y. C., Wah, Y. W., Watanabe, H., Woo, J. K., Yamanaka, T., and Yoshida, H. Y.

Abstract

A search for the rare decay KL→π0νν¯ was performed. With the data collected in 2015, corresponding to 2.2×1019 protons on target, a single event sensitivity of (1.30±0.01stat±0.14syst)×10−9 was achieved and no candidate events were observed. We set an upper limit of 3.0×10−9 for the branching fraction of KL→π0νν¯ at the 90% confidence level (C.L.), which improved the previous limit by almost an order of magnitude. An upper limit for KL→π0X0 was also set as 2.4×10−9 at the 90% C.L., where X0 is an invisible boson with a mass of 135 MeV/c2.

Published
2019

31. A new search for the KL→π0νν¯ and KL→π0X0 decays

Author

Ahn, J.K., Baek, K.Y., Banno, S., Beckford, B., Brubaker, B., Cai, T., Campbell, M., Carruth, C., Chen, S.H., Chu, S., Comfort, J., Duh, Y.T., Furukawa, T., Haraguchi, H., Hineno, T., Hsiung, Y.B., Hutcheson, M., Inagaki, T., Isoe, M., Iwai, E., Kamibayashi, T., Kamiji, I., Kawasaki, N., Kim, E.J., Kim, Y.J., Ko, J.W., Komatsubara, T.K., Kurilin, A.S., Lee, G.H., Lee, H.S., Lee, J.W., Lee, S.K., Lim, G.Y., Lin, C., Ma, J., Maeda, Y., Masuda, T., Matsumura, T., Mcfarland, D., Micallef, J., Miyazaki, K., Morgan, K., Murayama, R., Naito, D., Nakagiri, K., Nakajima, Y., Nakaya, Y., Nanjo, H., Nomura, T., Odani, Y., Ogata, R., Okuno, H., Ota, T., Ri, Y.D., Sasaki, M., Sasao, N., Sato, K., Sato, T., Seki, S., Shimogawa, T., Shinkawa, T., Shinohara, S., Shiomi, K., Son, J.S., Stevens, J., Su, S., Sugiyama, Y., Suzuki, S., Tajima, Y., Takahashi, G., Takashima, Y., Tecchio, M., Teo, I., Togawa, M., Toyoda, T., Tung, Y.C., Usuki, T., Wah, Y.W., Watanabe, H., Whallon, N., Woo, J.K., Xu, J., Yamaga, M., Yamamoto, S., Yamanaka, T., Yamauchi, H., Yanagida, Y., Yokota, H., Yoshida, H.Y., and Yoshimoto, H.

Subjects
Physics, Particle physics, 010308 nuclear & particles physics, Branching fraction, 0103 physical sciences, Pi, General Physics and Astronomy, 010306 general physics, 01 natural sciences
Abstract

We searched for the $CP$-violating rare decay of neutral kaon, $K_{L} \to \pi^0 \nu \overline{\nu}$, in data from the first 100 hours of physics running in 2013 of the J-PARC KOTO experiment. One candidate event was observed while $0.34\pm0.16$ background events were expected. We set an upper limit of $5.1\times10^{-8}$ for the branching fraction at the 90\% confidence level (C.L.). An upper limit of $3.7\times10^{-8}$ at the 90\% C.L. for the $K_{L} \to \pi^{0} X^{0}$decay was also set for the first time, where $X^{0}$ is an invisible particle with a mass of 135 MeV/$c^{2}$.

Published
2017

32. Search for the K−pp bound state via γd→K+π−X reaction at Eγ=1.5–2.4 GeV

Author

Tokiyasu, A.O., Niiyama, M., Parker, J.D., Ahn, D.S., Ahn, J.K., Ajimura, S., Akimune, H., Asano, Y., Chang, W.C., Chen, J.Y., Daté, S., Ejiri, H., Fujimura, H., Fujiwara, M., Fukui, S., Hasegawa, S., Hicks, K., Horie, K., Hotta, T., Hwang, S.H., Imai, K., Ishikawa, T., Iwata, T., Kato, Y., Kawai, H., Kino, K., Kohri, H., Kon, Y., Kumagai, N., Lin, D.L., Maeda, Y., Makino, S., Matsuda, T., Matsumura, T., Matsuoka, N., Mibe, T., Miyabe, M., Miyachi, M., Muramatsu, N., Murayama, R., Nakano, T., Nakatsugawa, Y., Nomachi, M., Ohashi, Y., Ohkuma, H., Ohta, T., Ooba, T., Oshuev, D.S., Rangacharyulu, C., Ryu, S.Y., Sakaguchi, A., Sawada, T., Shagin, P.M., Shiino, Y., Shimizu, H., Strokovsky, E.A., Sugaya, Y., Sumihama, M., Tang, J.L., Toi, Y., Toyokawa, H., Tsunemi, T., Uchida, M., Ungaro, M., Wakai, A., Wang, C.W., Wang, S.C., Yonehara, K., Yorita, T., Yoshimura, M., Yosoi, M., and Zegers, R.G.T.

Subjects
Nuclear and High Energy Physics
Published
2014
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34. A new search for the $K_{L} \to ��^0 ��\overline��$ and $K_{L} \to ��^{0} X^{0}$ decays

Author

Ahn, J. K., Baek, K. Y., Banno, S., Beckford, B., Brubaker, B., Cai, T., Campbell, M., Carruth, C., Chen, S. H., Chu, S., Comfort, J., Duh, Y. T., Furukawa, T., Haraguchi, H., Hineno, T., Hsiung, Y. B., Hutcheson, M., Inagaki, T., Isoe, M., Iwai, E., Kamibayashi, T., Kamiji, I., Kawasaki, N., Kim, E. J., Kim, Y. J., Ko, J. W., Komatsubara, T. K., Kurilin, A. S., Lee, G. H., Lee, H. S., Lee, J. W., Lee, S. K., Lim, G. Y., Lin, C., Ma, J., Maeda, Y., Masuda, T., Matsumura, T., Mcfarland, D., Micallef, J., Miyazaki, K., Morgan, K., Murayama, R., Naito, D., Nakagiri, K., Nakajima, Y., Nakaya, Y., Nanjo, H., Nomura, T., Odani, Y., Ogata, R., Okuno, H., Ota, T., Ri, Y. D., Sasaki, M., Sasao, N., Sato, K., Sato, T., Seki, S., Shimogawa, T., Shinkawa, T., Shinohara, S., Shiomi, K., Son, J. S., Stevens, J., Su, S., Sugiyama, Y., Suzuki, S., Tajima, Y., Takahashi, G., Takashima, Y., Tecchio, M., Teo, I., Togawa, M., Toyoda, T., Tung, Y. C., Usuki, T., Wah, Y. W., Watanabe, H., Whallon, N., Woo, J. K., Xu, J., Yamaga, M., Yamamoto, S., Yamanaka, T., Yamauchi, H., Yanagida, Y., Yokota, H., Yoshida, H. Y., and Yoshimoto, H.

Subjects
High Energy Physics - Experiment (hep-ex), FOS: Physical sciences
Abstract

We searched for the $CP$-violating rare decay of neutral kaon, $K_{L} \to ��^0 ��\overline��$, in data from the first 100 hours of physics running in 2013 of the J-PARC KOTO experiment. One candidate event was observed while $0.34\pm0.16$ background events were expected. We set an upper limit of $5.1\times10^{-8}$ for the branching fraction at the 90\% confidence level (C.L.). An upper limit of $3.7\times10^{-8}$ at the 90\% C.L. for the $K_{L} \to ��^{0} X^{0}$decay was also set for the first time, where $X^{0}$ is an invisible particle with a mass of 135 MeV/$c^{2}$., 11 pages, 5 figures, to be published in PTEP

Published
2016
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35. Interference effect between $��$ and $��(1520)$ production channels in the $��p \rightarrow K^+K^-p$ reaction near threshold

Author

Ryu, S. Y., Ahn, J. K., Nakano, T., Ahn, D. S., Ajimura, S., Akimune, H., Asano, Y., Chang, W. C., Chen, J. Y., Date, S., Ejiri, H., Fujimura, H., Fujiwara, M., Fukui, S., Hasegawa, S., Hicks, K., Horie, K., Hotta, T., Hwang, S. H., Imai, K., Ishikawa, T., Iwata, T., Kato, Y., Kawai, H., Kino, K., Kohri, H., Kon, Y., Kumagai, N., Lin, P. J., Maeda, Y., Makino, S., Matsuda, T., Matsuoka, N., Mibe, T., Miyabe, M., Miyachi, M., Morino, Y., Muramatsu, N., Murayama, R., Nakatsugawa, Y., Nam, S. i., Niiyama, M., Nomachi, M., Ohashi, Y., Ohkuma, H., Ohta, T., Ooba, T., Oshuev, D. S., Parker, J. D., Rangacharyulu, C., Sakaguchi, A., Sawada, T., Shagin, P. M., Shiino, Y., Shimizu, H., Strokovsky, E. A., Sugaya, Y., Sumihama, M., Tokiyasu, A. O., Toi, Y., Toyokawa, H., Tsunemi, T., Uchida, M., Ungaro, M., Wakai, A., Wang, C. W., Wang, S. C., Yonehara, K., Yorita, T., Yoshimura, M., Yosoi, M., and Zegers, R. G. T.

Subjects
FOS: Physical sciences, High Energy Physics::Experiment, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

The $��$-$��(1520)$ interference effect in the $��p\to K^+K^-p$ reaction has been measured for the first time in the energy range from 1.673 to 2.173 GeV. The relative phases between $��$ and $��(1520)$ production amplitudes were obtained in the kinematic region where the two resonances overlap. The measurement results support strong constructive interference when $K^+K^-$ pairs are observed at forward angles, but destructive interference for proton emission at forward angles. Furthermore, the observed interference effect does not account for the $\sqrt{s}=2.1$ GeV bump structure in forward differential cross sections for $��$ photoproduction. This fact suggests possible exotic structures such as a hidden-strangeness pentaquark state, a new Pomeron exchange and rescattering processes via other hyperon states.

Published
2016
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37. Long-lived neutral-kaon flux measurement for the KOTO experiment

Author

Masuda, T., primary, Ahn, J. K., additional, Banno, S., additional, Campbell, M., additional, Comfort, J., additional, Duh, Y. T., additional, Hineno, T., additional, Hsiung, Y. B., additional, Inagaki, T., additional, Iwai, E., additional, Kawasaki, N., additional, Kim, E. J., additional, Kim, Y. J., additional, Ko, J. W., additional, Komatsubara, T. K., additional, Kurilin, A. S., additional, Lee, G. H., additional, Lee, J. W., additional, Lee, S. K., additional, Lim, G. Y., additional, Ma, J., additional, MacFarland, D., additional, Maeda, Y., additional, Matsumura, T., additional, Murayama, R., additional, Naito, D., additional, Nakaya, Y., additional, Nanjo, H., additional, Nomura, T., additional, Odani, Y., additional, Okuno, H., additional, Ri, Y. D., additional, Sasao, N., additional, Sato, K., additional, Sato, T., additional, Seki, S., additional, Shimogawa, T., additional, Shinkawa, T., additional, Shiomi, K., additional, Son, J. S., additional, Sugiyama, Y., additional, Suzuki, S., additional, Tajima, Y., additional, Takahashi, G., additional, Takashima, Y., additional, Tecchio, M., additional, Togawa, M., additional, Toyoda, T., additional, Tung, Y. C., additional, Wah, Y. W., additional, Watanabe, H., additional, Woo, J. K., additional, Xu, J., additional, Yamanaka, T., additional, Yanagida, Y., additional, Yoshida, H. Y., additional, and Yoshimoto, H., additional

Published
2016
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39. Search for $K^-pp$ bound state via $��d \rightarrow K^+ ��^-X$ reaction at $E_��=1.5-2.4$ GeV

Author

Tokiyasu, A. O., Niiyama, M., Parker, J. D., Ahn, D. S., Ahn, J. K., Ajimura, S., Akimune, H., Asano, Y., Chang, W. C., Chen, J. Y., Dat��, S., Ejiri, H., Fujimura, H., Fujiwara, M., Fukui, S., Hasegawa, S., Hicks, K., Horie, K., Hotta, T., Hwang, S. H., Imai, K., Ishikawa, T., Iwata, T., Kato, Y., Kawai, H., Kino, K., Kohri, H., Kon, Y., Kumagai, N., Lin, D. L., Maeda, Y., Makino, S., Matsuda, T., Matsumura, T., Matsuoka, N., Mibe, T., Miyabe, M., Miyachi, M., Muramatsu, N., Murayama, R., Nakano, T., Nakatsugawa, Y., Nomachi, M., Ohashi, Y., Ohkuma, H., Ohta, T., Ooba, T., Oshuev, D. S., Rangacharyulu, C., Ryu, S. Y., Sakaguchi, A., Sawada, T., Shagin, P. M., Shiino, Y., Shimizu, H., Strokovsky, E. A., Sugaya, Y., Sumihama, M., Tang, J. L., Toi, Y., Toyokawa, H., Tsunemi, T., Uchida, M., Ungaro, M., Wakai, A., Wang, C. W., Wang, S. C., Yonehara, K., Yorita, T., Yoshimura, M., Yosoi, M., and Zegers, R. G. T.

Subjects
FOS: Physical sciences, Nuclear Experiment (nucl-ex)
Abstract

A search for $K^-pp$ bound state (the lightest kaonic nucleus) has been performed using the $��d \rightarrow K^+ ��^- \rm{X}$ reaction at E$_��$=1.5-2.4 GeV at LEPS/SPring-8. The differential cross section of $K^+ ��^-$ photo-production off deuterium has been measured for the first time in this energy region, and a bump structure was searched for in the inclusive missing mass spectrum. A statistically significant bump structure was not observed in the region from 2.22 to 2.36 GeV/$c^2$, and the upper limits of the differential cross section for the $K^-pp$ bound state production were determined to be 0.1$-$0.7 $��$ b (95$%$ confidence level) for a set of assumed binding energy and width values.

Published
2013
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44. Dot-matrix display using organic light-emitting diodes

Author

Wakimoto, T., primary, Ochi, H., additional, Kawami, S., additional, Ohata, H., additional, Nagayama, K., additional, Murayama, R., additional, Okuda, Y., additional, Nakada, H., additional, Tohma, T., additional, Naito, T., additional, and Abiko, H., additional

Published
1997
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49. MAPKs, activator protein-1 and nuclear factor-κB mediate production of interleukin-1β-stimulated cytokines, prostaglandin E2 and MMP-1 in human periodontal ligament cells.

Author

Murayama, R., Kobayashi, M., Takeshita, A., Yasui, T., and Yamamoto, M.

Abstract

Murayama R, Kobayashi M, Takeshita A, Yasui T, Yamamoto M. MAPKs, activator protein-1 and nuclear factor-κB mediate production of interleukin-1β-stimulated cytokines, prostaglandin E 2 and MMP-1 in human periodontal ligament cells. J Periodont Res 2011; 46: 568-575. © 2011 John Wiley & Sons A/S Background and Objective: Determination of the interleukin-1 (IL-1) signaling cascades that lead to the production of various inflammatory mediators and catabolic factors may clarify attractive targets for therapeutic intervention for periodontitis. We comprehensively assessed the involvement of MAPKs, activator protein-1 (AP-1) and nuclear factor-κB (NF-κB) in IL-1β-induced production of interleukin-6 (IL-6), interleukin-8 (IL-8), prostaglandin E2 (PGE2) and MMP-1 in human periodontal ligament cells. Material and Methods: Human periodontal ligament cells were pretreated with an inhibitor for each of the MAPKs or NF-κB and subsequently treated with IL-1β. Following treatment, phosphorylation of three types of MAPK (ERK, p38 MAPK and c-Jun N-terminal kinase), IκB kinase (IKK) α/β/γ and IκB-α, as well as the DNA binding activity of AP-1 and NF-κB and the production of IL-6, IL-8, PGE2 and MMP-1, were determined by western blotting, a gel mobility shift assay and ELISA, respectively. Results: The three MAPKs, simultaneously activated by IL-1β, mediated the subsequent DNA binding of AP-1 at various magnitudes, while IKKα/β/γ, IκB-α and NF-κB were also involved in the IL-1 signaling cascade. Furthermore, IL-1β stimulated the production of IL-6, IL-8, PGE2 and MMP-1 via activation of the three MAPKs and NF-κB, because inhibitors of these significantly suppressed the IL-1β-stimulated production of these factors. Conclusion: Our results strongly suggest that MAPK, AP-1 and NF-κB mediate the IL-1β-stimulated synthesis of IL-6, IL-8, PGE2 and MMP-1 in human periodontal ligament cells. Therefore, inhibition of activation of MAPK, AP-1 and/or NF-κB may lead to therapeutic effects on progression of periodontitis. [ABSTRACT FROM AUTHOR]

Published
2011
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