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411 results on '"Schacher, J"'

1. The \pi^+\pi^- Coulomb interaction study and its use in the data processing

Author

Adeva, B., Afanasyev, L., Anania, A., Aogaki, S., Benelli, A., Brekhovskikh, V., Cechak, T., Chiba, M., Chliapnikov, P., Drijard, D., Dudarev, A., Dumitriu, D., Federicova, P., Gorin, A., Gritsay, K., Guaraldo, C., Gugiu, M., Hansroul, M., Hons, Z., Horikawa, S., Iwashita, Y., Kluson, J., Kobayashi, M., Kruglova, L., Kulikov, A., Kulish, E., Lamberto, A., Lanaro, A., Lednicky, R., Marinas, C., Martincik, J., Nemenov, L., Nikitin, M., Okada, K., Olchevskii, V., Pentia, M., Penzo, A., Plo, M., Prusa, P., Rappazzo, G., Vidal, A. Romero, Ryazantsev, A., Rykalin, V., Saborido, J., Schacher, J., Sidorov, A., Smolik, J., Takeutchi, F., Trojek, T., Trusov, S., Urban, T., Vrba, T., Yazkov, V., Yoshimura, Y., and Zrelov, P.

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

In this work the Coulomb effects (Coulomb correlations) in $\pi^+\pi^-$ pairs produced in p + Ni collisions at 24 GeV/$c$, are studied using experimental $\pi^+\pi^-$ pair distributions in $Q$, the relative momentum in the pair center of mass system (c.m.s), and its projections $Q_L$ (longitudinal component) and $Q_t$ (transverse component) relative to the pair direction in the laboratory system (l.s.). The $Q$, $Q_L$, and $Q_t$ distributions of the {\sl Coulomb pairs} in the c.m.s. have been simulated assuming they are described by the phase space modified by the known point-like Coulomb correlation function $A_C(Q)$, corrected for small effects due to the nonpoint-like pair production and the strong two-pion interaction. The same distributions of {\sl non-Coulomb pairs} have been simulated according to the phase space, but without $A_C(Q)$. It is shown that the number of {\sl Coulomb pairs} in all $Q_t$ intervals, including the small $Q_t$ (small opening angles $\theta$ in the l.s.) is calculated with the theoretical precision better than 2\%. The comparison of the simulated and experimental numbers of {\sl Coulomb pairs} at small $Q_t$ allows us to check and correct the detection efficiency for the pairs with small $\theta$ (0.06 mrad and smaller). It is shown that {\sl Coulomb pairs} can be used as a new physical tool to check and correct the quality of the simulated events. The special property of the {\sl Coulomb pairs} is the possibility of checking and correcting the detection efficiency, especially for the pairs with small opening angles.

Published
2024

2. Investigation of $K^+K^-$ pairs in the effective mass region near $2m_K$

Author

Adeva, B., Afanasyev, L., Anania, A., Aogaki, S., Benelli, A., Brekhovskikh, V., Cechak, T., Chiba, M., Chliapnikov, P., Drijard, D., Dudarev, A., Dumitriu, D., Federicova, P., Gorin, A., Gritsay, K., Guaraldo, C., Gugiu, M., Hansroul, M., Hons, Z., Horikawa, S., Iwashita, Y., Karpukhin, V., Kluson, J., Kobayashi, M., Kruglova, L., Kulikov, A., Kulish, E., Lamberto, A., Lanaro, A., Lednicky, R., Mariñas, C., Martincik, J., Nemenov, L., Nikitin, M., Okada, K., Olchevskii, V., Pentia, M., Penzo, A., Plo, M., Prusa, P., Rappazzo, G., Vidal, A. Romero, Ryazantsev, A., Rykalin, V., Saborido, J., Schacher, J., Sidorov, A., Smolik, J., Takeutchi, F., Trojek, T., Trusov, S., Urban, T., Vrba, T., Yazkov, V., Yoshimura, Y., and Zrelov, P.

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

The DIRAC experiment at CERN investigated in the reaction $\rm{p}(24~\rm{GeV}/c) + Ni$ the particle pairs $K^+K^-, \pi^+ \pi^-$ and $p \bar{p}$ with relative momentum $Q$ in the pair system less than 100 MeV/c. Because of background influence studies, DIRAC explored three subsamples of $K^+K^-$ pairs, obtained by subtracting -- using time-of-flight (TOF) technique -- background from initial $Q$ distributions with $K^+K^-$ sample fractions more than 70\%, 50\% and 30\%. The corresponding pair distributions in $Q$ and in its longitudinal projection $Q_L$ were analyzed first in a Coulomb model, which takes into account only Coulomb final state interaction (FSI) and assuming point-like pair production. This Coulomb model analysis leads to a $K^+K^-$ yield increase of about four at $Q_L=0.5$ MeV/c compared to 100 MeV/c. In order to study contributions from strong interaction, a second more sophisticated model was applied, considering besides Coulomb FSI also strong FSI via the resonances $f_0(980)$ and $a_0(980)$ and a variable distance $r^*$ between the produced $K$ mesons. This analysis was based on three different parameter sets for the pair production. For the 70\% subsample and with best parameters, $3680\pm 370$ $K^+K^-$ pairs was found to be compared to $3900\pm 410$ $K^+K^-$ extracted by means of the Coulomb model. Knowing the efficiency of the TOF cut for background suppression, the total number of detected $K^+K^-$ pairs was evaluated to be around $40000\pm 10\%$, which agrees with the result from the 30\% subsample. The $K^+K^-$ pair number in the 50\% subsample differs from the two other values by about three standard deviations, confirming -- as discussed in the paper -- that experimental data in this subsample is less reliable.

Published
2022
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3. Summary Report of Physics Beyond Colliders at CERN

Author

Alemany, R., Burrage, C., Bartosik, H., Bernhard, J., Boyd, J., Brugger, M., Calviani, M., Carli, C., Charitonidis, N., Curtin, D., Dainese, A., de Roeck, A., Diehl, M., Döbrich, B., Evans, L., Feng, J. L., Ferro-Luzzi, M., Gatignon, L., Gilardoni, S., Gninenko, S., Graziani, G., Gschwendtner, E., Goddard, B., Hartin, A., Irastorza, I., Jaeckel, J., Jacobsson, R., Jungmann, K., Kirch, K., Kling, F., Krasny, W., Lamont, M., Lanfranchi, G., Lansberg, J-P., Lindner, A., Long, K., Magnon, A., Mallot, G., Vidal, F. Martinez, Moulson, M., Papucci, M., Pawlowski, J. M., Pedraza, I., Petridis, K., Pospelov, M., Pulawski, S., Redaelli, S., Rozanov, S., Rumolo, G., Ruoso, G., Schacher, J., Schnell, G., Schuster, P., Semertzidis, Y., Siemko, A., Spadaro, T., Stapnes, S., Stocchi, A., Ströher, H., Usai, G., Vallée, C., Venanzoni, G., Wilkinson, G., and Wing, M.

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

Physics Beyond Colliders is an exploratory study aimed at exploiting the full scientific potential of CERN's accelerator complex and its scientific infrastructure in the next two decades through projects complementary to the LHC, HL-LHC and other possible future colliders. These projects should target fundamental physics questions that are similar in spirit to those addressed by high-energy colliders, but that require different types of beams and experiments. A kick-off workshop held in September 2016 identified a number of areas of interest and working groups have been set-up to study and develop these directions. All projects currently under consideration are presented including physics motivation, a brief outline of the experimental set-up and the status of the corresponding beam and detector technological studies. The proposals are also put in context of the worldwide landscape and their implementation issues are discussed., Comment: This document (66 pages, 19 figures) is the summary document of the Physics Beyond Colliders (PBC) study. It follows the PBC mandate and draws on a whole set of documents produced in the context of PBC (https://pbc.web.cern.ch), in particular the reports of the QCD and BSM working groups also available at arXiv:1901.04482 and arXiv:1901.09966

Published
2019

4. Physics Beyond Colliders: QCD Working Group Report

Author

Dainese, A., Diehl, M., Di Nezza, P., Friedrich, J., Gaździcki, M., Graziani, G., Hadjidakis, C., Jäckel, J., Lansberg, J. P., Magnon, A., Mallot, G., Vidal, F. Martinez, Massacrier, L. M., Nemenov, L., Neri, N., Pawlowski, J. M., Puławski, S. M., Schacher, J., Schnell, G., Stocchi, A., Usai, G. L., Vallée, C., and Venanzoni, G.

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

This report summarises the main findings of the QCD Working Group in the CERN Physics Beyond Colliders Study.

Published
2019

5. First measurement of a long-lived $\pi^+ \pi^-$ atom lifetime

Author

Adeva, B., Afanasyev, L., Anania, A., Aogaki, S., Benelli, A., Brekhovskikh, V., Cechak, T., Chiba, M., Chliapnikov, P. V., Doskarova, P., Drijard, D., Dudarev, A., Dumitriu, D., Fluerasu, D., Gorin, A., Gorchakov, O., Gritsay, K., Guaraldo, C., Gugiu, M., Hansroul, M., Hons, Z., Horikawa, S., Iwashita, Y., Karpukhin, V., Kluson, J., Kobayashi, M., Kruglov, V., Kruglova, L., Kulikov, A., Kulish, E., Lamberto, A., Lanaro, A., Lednicky, R., Mariñas, C., Martincik, J., Nemenov, L., Nikitin, M., Okada, K., Olchevskii, V., Ovsiannikov, V., Pentia, M., Penzo, A., Plo, M., Prusa, P., Rappazzo, G. F., Vidal, A. Romero, Ryazantsev, A., Rykalin, V., Saborido, J., Schacher, J., Sidorov, A., Smolik, J., Takeutchi, F., Trojek, T., Trusov, S., Vrba, T., Yazkov, V., Yoshimura, Y., and Zrelov, P.

Subjects
High Energy Physics - Experiment, Nuclear Experiment
Abstract

The adapted DIRAC experiment at the CERN PS accelerator observed for the first time long-lived hydrogen-like $\pi^+\pi^-$ atoms, produced by protons hitting a beryllium target. A part of these atoms crossed the gap of 96~mm and got broken up in the 2.1~\textmu{}m thick platinum foil. Analysing the observed number of atomic pairs, $n_A^L= \left.436^{+157}_{-61}\right|_\mathrm{tot}$, the lifetime of the 2$p$ state is found to be ${\tau_{2p}=(\left.0.45^{+1.08}_{-0.30}\right|_\mathrm{tot}) \cdot10^{-11}}$s, not contradicting the corresponding QED $2p$ state lifetime ${\tau_{2p}^\mathrm{QED}=1.17 \cdot 10^{-11}}$s. This lifetime value is three orders of magnitude larger than our previously measured value of the $\pi^+\pi^-$ atom ground state lifetime $\tau=(\left.3.15^{+0.28}_{-0.26}\right|_\mathrm{tot})\cdot 10^{-15}$s. Further studies of long-lived $\pi^+\pi^-$ atoms will allow to measure energy differences between $p$ and $s$ atomic states and so to determine $\pi\pi$ scattering lengths with the aim to check QCD predictions., Comment: 7 pages, 8 figures

Published
2018
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6. Measurement of the $\pi K$ atom lifetime and the $\pi K$ scattering length

Author

DIRAC Collaboration, Adeva, B., Afanasyev, L., Allkofer, Y., Amsler, C., Anania, A., Aogaki, S., Benelli, A., Brekhovskikh, V., Cechak, T., Chiba, M., Chliapnikov, P., Drijard, D., Dudarev, A., Dumitriu, D., Federicova, P., Fluerasu, D., Gorin, A., Gorchakov, O., Gritsay, K., Guaraldo, C., Gugiu, M., Hansroul, M., Hons, Z., Horikawa, S., Iwashita, Y., Karpukhin, V., Kluson, J., Kobayashi, M., Kruglov, V., Kruglova, L., Kulikov, A., Kulish, E., Kuptsov, A., Lamberto, A., Lanaro, A., Lednicky, R., Marinas, C., Martincik, J., Nemenov, L., Nikitin, M., Okada, K., Olchevskii, V., Pentia, M., Penzo, A., Plo, M., Prusa, P., Rappazzo, G., Vidal, A. Romero, Ryazantsev, A., Rykalin, V., Saborido, J., Schacher, J., Sidorov, A., Smolik, J., Takeutchi, F., Tauscher, L., Trojek, T., Trusov, S., Urban, T., Vrba, T., Yazkov, V., Yoshimura, Y., Zhabitsky, M., and Zrelov, P.

Subjects
High Energy Physics - Experiment, Nuclear Experiment
Abstract

After having announced the statistically significant observation (5.6~$\sigma$) of the new exotic $\pi K$ atom, the DIRAC experiment at the CERN proton synchrotron presents the measurement of the corresponding atom lifetime, based on the full $\pi K$ data sample: $\tau = (5.5^{+5.0}_{-2.8}) \cdot 10^{-15}s$. By means of a precise relation ($<1\%$) between atom lifetime and scattering length, the following value for the S-wave isospin-odd $\pi K$ scattering length $a_0^{-}~=~\frac{1}{3}(a_{1/2}-a_{3/2})$ has been derived: $\left|a_0^-\right| = (0.072^{+0.031}_{-0.020}) M_{\pi}^{-1}$., Comment: 18 pages, 17 figures

Published
2017
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7. Summary Report of Physics Beyond Colliders at CERN

Author

Alemany, R, Burrage, C, Bartosik, H, Bernhard, J, Boyd, J, Brugger, M, Calviani, M, Carli, C, Charitonidis, N, Curtin, D, Dainese, A, Roeck, A de, Diehl, M, Döbrich, B, Evans, L, Feng, JL, Ferro-Luzzi, M, Gatignon, L, Gilardoni, S, Gninenko, S, Graziani, G, Gschwendtner, E, Goddard, B, Hartin, A, Irastorza, I, Jaeckel, J, Jacobsson, R, Jungmann, K, Kirch, K, Kling, F, Krasny, W, Lamont, M, Lanfranchi, G, Lansberg, J-P, Lindner, A, Long, K, Magnon, A, Mallot, G, Vidal, F Martinez, Moulson, M, Papucci, M, Pawlowski, JM, Pedraza, I, Petridis, K, Pospelov, M, Pulawski, S, Redaelli, S, Rozanov, S, Rumolo, G, Ruoso, G, Schacher, J, Schnell, G, Schuster, P, Semertzidis, Y, Siemko, A, Spadaro, T, Stapnes, S, Stocchi, A, Ströher, H, Usai, G, Vallée, C, Venanzoni, G, Wilkinson, G, and Wing, M

Subjects
hep-ex, hep-ph, physics.ins-det
Abstract

Physics Beyond Colliders is an exploratory study aimed at exploiting the fullscientific potential of CERN's accelerator complex and its scientificinfrastructure in the next two decades through projects complementary to theLHC, HL-LHC and other possible future colliders. These projects should targetfundamental physics questions that are similar in spirit to those addressed byhigh-energy colliders, but that require different types of beams andexperiments. A kick-off workshop held in September 2016 identified a number ofareas of interest and working groups have been set-up to study and developthese directions. All projects currently under consideration are presentedincluding physics motivation, a brief outline of the experimental set-up andthe status of the corresponding beam and detector technological studies. Theproposals are also put in context of the worldwide landscape and theirimplementation issues are discussed.

Published
2019

8. First $\pi K$ atom lifetime and $\pi K$ scattering length measurements

Author

Adeva, B., Afanasyev, L., Allkofer, Y., Amsler, C., Anania, A., Aogaki, S., Benelli, A., Brekhovskikh, V., Cechak, T., Chiba, M., Chliapnikov, P., Ciocarlan, C., Constantinescu, S., Doskarova, P., Drijard, D., Dudarev, A., Duma, M., Dumitriu, D., Fluerasu, D., Gorin, A., Gorchakov, O., Gritsay, K., Guaraldo, C., Gugiu, M., Hansroul, M., Hons, Z., Horikawa, S., Iwashita, Y., Karpukhin, V., Kluson, J., Kobayashi, M., Kruglov, V., Kruglova, L., Kulikov, A., Kulish, E., Kuptsov, A., Lamberto, A., Lanaro, A., Lednicky, R., Mariñas, C., Martincik, J., Nemenov, L., Nikitin, M., Okada, K., Olchevskii, V., Pentia, M., Penzo, A., Plo, M., Ponta, T., Prusa, P., Rappazzo, G., Vidal, A. Romero, Ryazantsev, A., Rykalin, V., Schacher, J., Sidorov, A., Smolik, J., Sugimoto, S., Takeutchi, F., Tauscher, L., Trojek, T., Trusov, S., Urban, T., Vrba, T., Yazkov, V., Yoshimura, Y., Zhabitsky, M., and Zrelov, P.

Subjects
Nuclear Experiment, High Energy Physics - Experiment
Abstract

The results of a search for hydrogen-like atoms consisting of $\pi^{\mp}K^{\pm}$ mesons are presented. Evidence for $\pi K$ atom production by 24 GeV/c protons from CERN PS interacting with a nickel target has been seen in terms of characteristic $\pi K$ pairs from their breakup in the same target ($178 \pm 49$) and from Coulomb final state interaction ($653 \pm 42$). Using these results the analysis yields a first value for the $\pi K$ atom lifetime of $\tau=(2.5_{-1.8}^{+3.0})$ fs and a first model-independent measurement of the S-wave isospin-odd $\pi K$ scattering length $\left|a_0^-\right|=\frac{1}{3}\left|a_{1/2}-a_{3/2}\right|= \left(0.11_{-0.04}^{+0.09} \right)M_{\pi}^{-1}$ ($a_I$ for isospin $I$)., Comment: 14 pages, 8 figures

Published
2014
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9. Determination of $\pi\pi$ scattering lengths from measurement of $\pi^+\pi^-$ atom lifetime

Author

Adeva, B., Afanasyev, L., Benayoun, M., Benelli, A., Berka, Z., Brekhovskikh, V., Caragheorgheopol, G., Cechak, T., Chiba, M., Chliapnikov, P. V., Ciocarlan, C., Constantinescu, S., Costantini, S., Curceanu, C., Doskarova, P., Dreossi, D., Drijard, D., Dudarev, A., Ferro-Luzzi, M., Pazos, J. L. Fungueiriño, Torreira, M. Gallas, Gerndt, J., Gianotti, P., Goldin, D., Gomez, F., Gorin, A., Gorchakov, O., Guaraldo, C., Gugiu, M., Hansroul, M., Hons, Z., Hosek, R., Iliescu, M., Karpukhin, V., Kluson, J., Kobayashi, M., Kokkas, P., Komarov, V., Kruglov, V., Kruglova, L., Kulikov, A., Kuptsov, A., Kuroda, K. I., Lamberto, A., Lanaro, A., Lapshin, V., Lednicky, R., Leruste, P., Sandri, P. Levi, Aguera, A. Lopez, Lucherini, V., Maki, T., Manuilov, I., Marin, J., Narjoux, J. L., Nemenov, L., Nikitin, M., Pardo, T. Nunez, Okada, K., Olchevskii, V., Pazos, A., Pentia, M., Penzo, A., Perreau, J. M., Plo, M., Ponta, T., Rappazzo, G. F., Riazantsev, A., Rodriguez, J. M., Fernandez, A. Rodriguez, Vidal, A. Romero, Ronjin, V. M., Rykalin, V., Saborido, J., Santamarina, C., Schacher, J., Schuetz, C., Sidorov, A., Smolik, J., Takeutchi, F., Tarasov, A., Tauscher, L., Tobar, M. J., Trojek, T., Trusov, S., Utkin, V., Doce, O. Vázquez, Vlachos, S., Voskresenskaya, O., Vrba, T., Willmott, C., Yazkov, V., Yoshimura, Y., Zhabitsky, M., and Zrelov, P.

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

The DIRAC experiment at CERN has achieved a sizeable production of $\pi^+\pi^-$ atoms and has significantly improved the precision on its lifetime determination. From a sample of 21227 atomic pairs, a 4% measurement of the S-wave $\pi\pi$ scattering length difference $|a_0-a_2| = (.0.2533^{+0.0080}_{-0.0078}|_\mathrm{stat}.{}^{+0.0078}_{-0.0073}|_\mathrm{syst})M_{\pi^+}^{-1}$ has been attained, providing an important test of Chiral Perturbation Theory., Comment: 6 pages, 6 figures

Published
2011
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10. Evidence for $\pi K$-atoms with DIRAC

Author

Adeva, B., Afanasyev, L., Allkofer, Y., Amsler, C., Anania, A., Benelli, A., Brekhovskikh, V., Caragheorgheopol, G., Cechak, T., Chiba, M., Chliapnikov, P., Ciocarlan, C., Constantinescu, S., Curceanu, C., Detraz, C., Dreossi, D., Drijard, D., Dudarev, A., Duma, M., Dumitriu, D., Fungueiriño, J. L., Gerndt, J., Gorin, A., Gorchakov, O., Gritsay, K., Guaraldo, C., Gugiu, M., Hansroul, M., Hons, Z., Horikawa, S., Iliescu, M., Karpukhin, V., Kluson, J., Kobayashi, M., Komarov, V., Kruglov, V., Kruglova, L., Kulikov, A., Kuptsov, A., Kurochkin, I., Lamberto, A., Lanaro, A., Lapshin, V., Lednicky, R., Sandri, P. Levi, Aguera, A. Lopez, Lucherini, V., Manuilov, I., Mariñas, C., Nemenov, L., Nikitin, M., Okada, K., Olchevskii, V., Pentia, M., Penzo, A., Pló, M., Rappazzo, G. F., Regenfus, C., Rochet, J., Romero, A., Ronjin, V., Ryazantsev, A., Rykalin, V., Saborido, J., Schacher, J., Sidorov, A., Smolik, J., Sugimoto, S., Takeutchi, F., Tarasov, A., Tauscher, L., Trojek, T., Trusov, S., Utkin, V., Doce, O. Vázquez, Vrba, T., Yazkov, V., Yoshimura, Y., Zhabitsky, M., and Zrelov, P.

Subjects
High Energy Physics - Experiment
Abstract

We present evidence for the first observation of electromagnetically bound $\pi^\pm K^\mp$-pairs ($\pi K$-atoms) with the DIRAC experiment at the CERN-PS. The $\pi K$-atoms are produced by the 24 GeV/c proton beam in a thin Pt-target and the $\pi^\pm$ and $K^\mp$-mesons from the atom dissociation are analyzed in a two-arm magnetic spectrometer. The observed enhancement at low relative momentum corresponds to the production of 173 $\pm$ 54 $\pi K$-atoms. The mean life of $\pi K$-atoms is related to the s-wave $\pi K$-scattering lengths, the measurement of which is the goal of the experiment. From these first data we derive a lower limit for the mean life of 0.8 fs at 90% confidence level., Comment: 15 pages, 9 figures

Published
2009
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11. HadAtom05, Workshop on Hadronic Atoms

Author

Afanasyev, L., Colangelo, G., and Schacher, J.

Subjects
High Energy Physics - Phenomenology
Abstract

These are the proceedings of the workshop "HadAtom05", held at the University of Bern, Switzerland, February 15 and 16, 2005. The main topics of the workshop concerned the physics of hadronic atoms, and in this context recent results from experiments and theory were presented. These proceedings contain the list of participants, the scientific program and a short contribution from each speaker., Comment: 28 pages, 5 figures, proceedings of the workshop "HadAtom05", University of Bern, Switzerland, February 15 and 16, 2005

Published
2005

12. HadAtom03

Author

Gasser, J., Rusetsky, A., and Schacher, J.

Subjects
High Energy Physics - Phenomenology
Abstract

These are the proceedings of the workshop "HadAtom03," held at the European Centre for Theoretical Nuclear Physics and Related Studies (ECT*), Trento (Italy), October 13 - 17, 2003. The main topics discussed at the workshop were the physics of hadronic atoms and in this context recent results in experiment and theory. Included here are the list of participants, the scientific program and a short contribution from each speaker., Comment: 46 pages, 16 postscript figures, Proceedings of the workshop "HadAtom03," 13-17 October Trento, Italy

Published
2004

13. HadAtom02

Author

Afanasyev, L., Lanaro, A., and Schacher, J.

Subjects
High Energy Physics - Phenomenology
Abstract

These are the proceedings of the workshop "HadAtom02", held at the CERN, October 14 - 15, 2002. The main topic of the workshop concerned the physics of hadronic atoms and in this contest recent results from experiments and theory were presented. These proceedings contain the list of participants, the scientific program and a short contribution from each speaker., Comment: 35 pages, 11 postscript figures

Published
2003

14. HadAtom01

Author

Gasser, J., Rusetsky, A., and Schacher, J.

Subjects
High Energy Physics - Phenomenology
Abstract

These are the proceedings of the workshop "HadAtom01", held at the Institut fuer Theoretische Physik, Universitaet Bern, October 11 - 12, 2001. The main topics discussed at the workshop were the physics of hadronic atoms and in this context recent results in experiment and theory. Included here are the list of participants, the scientific program and a short contribution from each speaker., Comment: 30 pages, 5 postscript figures

Published
2001

15. Antimatter and Matter Production in Heavy Ion Collisions at CERN (The NEWMASS Experiment NA52)

Author

Ambrosini, G., Arsenescu, R., Baglin, C., Beck, H. P., Borer, K., Bussiere, A., Elsener, K., Gorodetzky, Ph., Guillaud, J. P., Hess, P., Kabana, S., Klingenberg, R., Lehmann, G., Linden, T., Lohmann, K. D., Mommsen, R., Moser, U., Pretzl, K., Schacher, J., Spiwoks, R., Stoffel, F., Tuominiemi, J., and Weber, M.

Subjects
Nuclear Experiment
Abstract

Besides the dedicated search for strangelets NA52 measures light (anti)particle and (anti)nuclei production over a wide range of rapidity. Compared to previous runs the statistics has been increased in the 1998 run by more than one order of magnitude for negatively charged objects at different spectrometer rigidities. Together with previous data taking at a rigidity of -20 GeV/c we obtained 10^6 antiprotons 10^3 antideuterons and two antihelium3 without centrality requirements. We measured nuclei and antinuclei (p,d,antiprotons, antideuterons) near midrapidity covering an impact parameter range of b=2-12 fm. Our results strongly indicate that nuclei and antinuclei are mainly produced via the coalescence mechanism. However the centrality dependence of the antibaryon to baryon ratios show that antibaryons are diminished due to annihilation and breakup reactions in the hadron dense environment. The volume of the particle source extracted from coalescence models agrees with results from pion interferometry for an expanding source. The chemical and thermal freeze-out of nuclei and antinuclei appear to coincide with each other and with the thermal freeze-out of hadrons., Comment: 12 pages, 8 figures, to appear in the proceedings of the conference on 'Fundamental Issues in Elementary Matter' Bad Honnef, Germany, Sept. 25-29, 2000

Published
2000
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16. Centrality dependence of K+ produced in Pb+Pb collisions at 158 GeV per nucleon

Author

NA52 collaboration, Arsenescu, R., Baglin, C., Beck, H. P., Borer, K., Bussiere, A., Elsener, K., Gorodetzky, Ph., Guillaud, J. P., Kabana, S., Klingenberg, R., Lehmann, G., Linden, T., Lohmann, K. D., Mommsen, R., Moser, U., Pretzl, K., Schacher, J., Spiwoks, R., Tuominiemi, J., and Weber, M.

Subjects
High Energy Physics - Experiment
Abstract

The NA52 collaboration searches for a discontinuous behaviour of charged kaons produced in Pb+Pb collisions at 158 A GeV as a function of the impact parameter, which could reveal a hadron to quark-gluon plasma (QGP) phase transition. The K+ yield is found to grow proportional to the number of participating ('wounded') nucleons N, above N=100. Previous NA52 data agree with the above finding and show a discontinuous behaviour in the kaon centrality dependence near N=100, marking the onset of strangeness enhancement -over e.g. p+A data at the same \sqrt{s}- in a chemically equilibrated phase., Comment: 2 pages, 2 figures, Proceedings of the Vth International Conference on Strangeness in Quark Matter, 20-25 July 2000, Berkeley, California. To appear in Journal of Physics G: Nuclear and Particle Physics

Published
2000
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17. Experimental status of pionium at CERN

Author

Schacher, J. and Collaboration, DIRAC

Subjects
High Energy Physics - Phenomenology
Abstract

The DIRAC Collaboration presents a first search for "atomic pi(+) pi(-) pairs" from ionization of pionium., Comment: 2 pages, LaTex, 2 figures, talk at Chiral Dynamics 2000, Newport News (USA), July 17-20, 2000

Published
2000
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18. HadAtom99

Author

Gasser, J., Rusetsky, A., and Schacher, J.

Subjects
High Energy Physics - Phenomenology
Abstract

These are the proceedings of the workshop "HadAtom99", held at the Institut fuer Theoretische Physik, Universitaet Bern, October 14-15, 1999. The main topics discussed at the workshop were the physics of hadronic atoms and in this context recent results from Chiral Perturbation Theory. Included here are the program, the list of participants and a short summary provided by the speakers., Comment: 31 pages, LaTeX-file, 6 figures embedded, acknowledgments of funding organizations added

Published
1999

19. Working group on $\pi\pi$ and $\pi$N interactions - Summary

Author

Meißner, Ulf-G., Sevior, Martin, Badertscher, A., Borasoy, B., Büttiker, P., Höhler, G., Knecht, M., Krehl, O., Lowe, J., Mojzis, M., Müller, G., Patarakin, O., Pavan, M., Rusetsky, A., Sainio, M. E., Schacher, J., Smith, G., Steininger, S., and Vereshagin, V.

Subjects
High Energy Physics - Phenomenology, Nuclear Theory
Abstract

This is the summary of the working group on $\pi\pi$ and $\pi$N interactions of the Chiral Dynamics Workshop in Mainz, September 1-5, 1997. Each talk is represented by an extended one page abstract. Some additional remarks by the convenors are added, Comment: 20 pp, LaTeX2e, uses epsf, 1 fig

Published
1997
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20. Upgraded DIRAC spectrometer at CERN PS for the investigation of ππ and πK atoms

Author

Adeva, B., Afanasyev, L., Allkofer, Y., Amsler, C., Anania, A., Aogaki, S., Benelli, A., Brekhovskikh, V., Caragheorgheopol, Gh., Cechak, T., Chiba, M., Chliapnikov, P., Ciocarlan, C., Constantinescu, S., Detraz, C., Doskarova, P., Drijard, D., Dudarev, A., Duma, M., Dumitriu, D., Fluerasu, D., Gorin, A., Gorchakov, O., Gritsay, K., Guaraldo, C., Gugiu, M., Hansroul, M., Hons, Z., Horikawa, S., Iwashita, Y., Karpukhin, V., Kluson, J., Kobayashi, M., Kruglov, V., Kruglova, L., Kulikov, A., Kulish, E., Kuptsov, A., Lamberto, A., Lanaro, A., Lednicky, R., Mariñas, C., Martincik, J., Nemenov, L., Nikitin, M., Okada, K., Olchevskii, V., Pentia, M., Penzo, A., Plo, M., Prusa, P., Rappazzo, G.F., Vidal, A. Romero, Ryazantsev, A., Rykalin, V., Saborido, J., Schacher, J., Sidorov, A., Smolik, J., Takeutchi, F., Tauscher, L., Trojek, T., Trusov, S., Ullaland, O., Urban, T., Vrba, T., Yazkov, V., Yoshimura, Y., Zhabitsky, M., and Zrelov, P.

Published
2016
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21. Investigation of <math><msup><mi>K</mi><mo>+</mo></msup><msup><mi>K</mi><mo>−</mo></msup></math> pairs in the effective mass region near <math><mn>2</mn><msub><mi>m</mi><mi>K</mi></msub></math>

Author

Adeva, B., Afanasyev, L., Anania, A., Aogaki, S., Benelli, A., Brekhovskikh, V., Cechak, T., Chiba, M., Chliapnikov, P., Drijard, D., Dudarev, A., Dumitriu, D., Federicova, P., Gorin, A., Gritsay, K., Guaraldo, C., Gugiu, M., Hansroul, M., Hons, Z., Horikawa, S., Iwashita, Y., Karpukhin, V., Kluson, J., Kobayashi, M., Kruglova, L., Kulikov, A., Kulish, E., Lamberto, A., Lanaro, A., Lednicky, R., Mari??as, C., Martincik, J., Nemenov, L., Nikitin, M., Okada, K., Olchevskii, V., Pentia, M., Penzo, A., Plo, M., Prusa, P., Rappazzo, G., Romero Vidal, A., Ryazantsev, A., Rykalin, V., Saborido, J., Schacher, J., Sidorov, A., Smolik, J., Takeutchi, F., Trojek, T., Trusov, S., Urban, T., Vrba, T., Yazkov, V., Yoshimura, Y., and Zrelov, P.

Abstract

The DIRAC experiment at CERN investigated in the reaction p(24 GeV/c)+Ni the particle pairs K+K−,π+π−, and pp¯ with relative momentum Q in the pair system less than 100 MeV/c. Because of background influence studies, DIRAC explored three subsamples of K+K− pairs, obtained by subtracting-using the time-of-flight (TOF) technique-the background from initial Q distributions with K+K− sample fractions more than 70%, 50%, and 30%. The corresponding pair distributions in Q and in its longitudinal projection QL were analyzed first in a Coulomb model, which takes into account only the Coulomb final-state interaction (FSI) and assuming pointlike pair production. This Coulomb model analysis leads to a K+K− yield increase of about four at QL=0.5 MeV/c compared to 100 MeV/c. In order to study contributions from strong interaction, a second more sophisticated model was applied, considering also strong FSI via the resonances f0(980) and a0(980) and a variable distance r* between the produced K mesons besides Coulomb FSI. This analysis was based on three different parameter sets for the pair production. For the 70% subsample and with the best parameters, 3680±370 K+K− pairs were found to be compared to 3900±410 K+K− extracted by means of the Coulomb model. Knowing the efficiency of the TOF cut for background suppression, the total number of detected K+K− pairs was evaluated to be around 40000±10%, which agrees with the result from the 30% subsample. The K+K− pair number in the 50% subsample differs from the two other values by about three standard deviations, confirming—as discussed in the paper—that experimental data in this subsample is less reliable. In summary, the upgraded DIRAC experiment observed increased K+K− production at small relative momentum Q. The pair distribution in Q is well described by Coulomb FSI, whereas a potential influence from strong interaction in this Q region is insignificant within experimental errors.

Published
2022

23. Strangelet search and particle production studies in Pb+Pb collisions at 158 AGeV/c at CERN SPS

Author

Stoffel, F., Ambrosini, G., Appelquist, G., Arsenescu, R., Baglin, C., Beringer, J., Bohm, C., Borer, K., Bussière, A., Dittus, F., Elsener, K., Frei, D., Gorodetzky, Ph., Guillaud, J. P., Hess, P., Hugentobler, E., Kabana, S., Klingenberg, R., Lindén, T., Lohmann, K. D., Mommsen, R., Moser, U., Pal, T., Pretzl, K., Schacher, J., Selldén, B., Stoffel, F., Tuominiemi, J., Weber, M., Zhang, Q. P., and the Newmass (NA52) Collaboration

Published
1996
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24. A measurement of electron-tau universality from decays of intermediate vector bosons at the CERN $$\bar pp$$ collider

Author

Alitti, J., Ambrosini, G., Ansari, R., Autiero, D., Bareyre, P., Bertram, I. A., Blaylock, G., Bonamy, P., Bonesini, M., Borer, K., Bourliaud, M., Buskulic, D., Carboni, G., Cavalli, D., Cavasinni, V., Cenci, P., Chollet, J. C., Conta, C., Costa, G., Costantini, F., Cozzi, L., Cravero, A., Curatolo, M., Dell'Acqua, A., DelPrete, T., DeWolf, R. S., DiLella, L., Ducros, Y., Egan, G. F., Einsweiler, K. F., Esposito, B., Fayard, L., Federspiel, A., Ferrari, R., Fraternali, M., Froidevaux, D., Fumagalli, G., Gaillard, J. M., Gianotti, F., Gildemeister, O., Gössling, C., Goggi, V. G., Grünendahl, S., Hara, K., Hellman, S., Hrivnac, J., Hufnagel, H., Hugentobler, E., Hultqvist, K., Iacopini, E., Incandela, J., Jakobs, K., Jenni, P., Kluge, E. E., Kurz, N., Lami, S., Lariccia, P., Lefebvre, M., Linssen, L., Livan, M., Lubrano, P., Magneville, C., Mandelli, L., Mapelli, L., Mazzanti, M., Meier, K., Merkel, B., Meyer, J. P., Moniez, M., Moning, R., Morganti, M., Müller, L., Munday, D. J., Nessi, M., Nessi-Tedaldi, F., Onions, C., Pal, T., Parker, M. A., Parrour, G., Pastore, F., Pennacchio, E., Pentney, J. M., Pepe, M., Perini, L., Petridou, C., Petroff, P., Plothow-Besch, H., Polesello, G., Poppleton, A., Pretzl, K., Primavera, M., Punturo, M., Repellin, J. P., Rimoldi, A., Sacchi, M., Scampoli, P., Schacher, J., Simak, V., Singh, S. L., Sondermann, V., Stapnes, S., Stirling, A. V., Talamonti, C., Tondini, F., Tovey, S. N., Tsesmelis, E., Unal, G., Valdata-Nappi, M., Vercesi, V., Weidberg, A. R., Wells, P. S., White, T. O., Wood, D. R., Wotton, S. A., Zaccone, H., Zylberstejn, A., and UA2 Collaboration

Published
1991
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25. A measurement of two-jet decays of theW andZ bosons at the CERN $$\bar p$$ p collider

Author

Alitti, J., Ansari, R., Ansorge, R. E., Autiero, D., Bareyre, P., Blaylock, G., Bonamy, P., Bonesini, M., Borer, K., Bourliaud, M., Buskulic, D., Carboni, G., Cavalli, D., Cavasinni, V., Cenci, P., Chollet, J. C., Conta, C., Costa, G., Costantini, F., Cravero, A., Dell'Acqua, A., DelPrete, T., DeWolf, R. S., DiLella, L., Egan, G. F., Einsweiler, K. F., Fayard, L., Federspiel, A., Ferrari, R., Fraternali, M., Froidevaux, D., Fumagalli, G., Gaillard, J. M., Gianotti, F., Gildemeister, O., Gössling, C., Goggi, V. G., Grünendahl, S., Hara, K., Hellman, S., Hugentobler, E., Hultqvist, K., Iacopini, E., Incandela, J., Jakobs, K., Jenni, P., Kluge, E. E., Kurz, N., Lami, S., Lariccia, P., Lefebvre, M., Linssen, L., Livan, M., Lubrano, P., Magneville, C., Mandelli, L., Mapelli, L., Mazzanti, M., Meier, K., Merkel, B., Meyer, J. P., Moniez, M., Moning, R., Morganti, M., Müller, L., Munday, D. J., Onions, C., Pal, T., Parker, M. A., Parrour, G., Pastore, F., Pennacchio, E., Pentney, J. M., Pepe, M., Perini, L., Petridou, C., Petroff, P., Plothow-Besch, H., Polesello, G., Poppleton, A., Pretzl, K., Primavera, M., Punturo, M., Rasmussen, L., Repellin, J. P., Rimoldi, A., Scampoli, P., Schacher, J., Simak, V., Singh, S. L., Stapnes, S., Stirling, A. V., Tondini, F., Tovey, S. N., Tsesmelis, E., Unal, G., Valdata-Nappi, M., Vercesi, V., Weidberg, A. R., Wells, P. S., White, T. O., Wood, D. R., Wotton, S. A., Zaccone, H., and UA2 Collaboration

Published
1991
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26. Measurement of the transverse momentum distributions ofW andZ bosons at the CERN $$\bar pp$$ collider

Author

Alitti, J., Ansari, R., Ansorge, R. E., Autiero, D., Bagnaia, P., Bareyre, P., Blaylock, G., Bonamy, P., Bonesini, M., Booth, C. N., Borer, K., Buskulic, D., Carboni, G., Cavalli, D., Cavasinni, V., Cenci, P., Chollet, J. C., Conta, C., Costa, G., Costantini, F., Dell'Acqua, A., DeLotto, B., DelPrete, T., DeWolf, R. S., DiLella, L., Egan, G. F., Einsweiler, K. F., Fayard, L., Federspiel, A., Ferrari, R., Fraternali, M., Froidevaux, D., Fumagalli, G., Gaillard, J. M., Gianotti, F., Gildemeister, O., Gössling, C., Goggi, V. G., Grünendahl, S., Hara, K., Hellman, S., Hugentobler, E., Hultqvist, K., Iacopini, E., Incandela, J., Jakobs, K., Jenni, P., Kluge, E. E., Kurz, N., Lami, S., Lariccia, P., Lefebvre, M., Linssen, L., Livan, M., Lubrano, P., Magneville, C., Mandelli, L., Mapelli, L., Mazzanti, M., Meier, K., Merkel, B., Meyer, J. P., Moniez, M., Moning, R., Morganti, M., Müller, L., Munday, D. J., Onions, C., Pal, T., Parker, M. A., Parrour, G., Pastore, F., Pennacchio, E., Pentney, J. M., Pepe, M., Perini, L., Petridou, C., Petroff, P., Plothow-Besch, H., Polesello, G., Poppleton, A., Primavera, M., Rasmussen, L., Repellin, J. P., Rimoldi, A., Scampoli, P., Schacher, J., Singh, S. L., Stapnes, S., Stirling, A. V., Tovey, S. N., Valdata-Nappi, M., Vercesi, V., Weidberg, A. R., Wells, P. S., White, T. O., Wood, D. R., Wotton, S. A., Zaccone, H., and UA 2 Collaboration

Published
1990
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27. Search for top quark production at the CERN $$\bar pp$$ collider

Author

Åkesson, T., Alitti, J., Ansari, R., Ansorge, R. E., Bagnaia, P., Bareyre, P., Blaylock, G., Bonamy, P., Bonesini, M., Borer, K., Buskulie, D., Carboni, G., Cavalli, D., Cavasinni, V., Cenci, P., Chollet, J. C., Conta, C., Costa, G., Costantini, F., Dell'Acqua, A., De Lotto, B., Del Prete, T., De Wolf, R. S., Di Lella, L., Egan, G. F., Einsweiler, K. F., Fayard, L., Federspiel, A., Ferrari, R., Fraternali, M., Froidevaux, D., Fumagalli, G., Gaillard, J. M., Gianotti, F., Gildemeister, O., Gössling, C., Goggi, V. G., Grünendahl, S., Hansen, J. R., Hara, K., Hellman, S., Hugentobler, E., Hultqvist, K., Iacopini, E., Incandela, J., Jakobs, K., Jenni, P., Kluge, E. E., Kurz, N., Lami, S., Lariccia, P., Lefebvre, M., Linssen, L., Livan, M., Lubrano, P., Magneville, C., Mandelli, L., Mapelli, L., Mazzanti, M., Meier, K., Merkel, B., Meyer, J. P., Moniez, M., Moning, R., Morganti, M., Müller, L., Munday, D. J., Onions, C., Pal, T., Parker, M. A., Parrour, G., Pastore, F., Pennacchio, E., Pentney, J. M., Pepe, M., Perini, L., Petridou, C., Petroff, P., Plothow-Besch, H., Primavera, M., Polesello, G., Poppleton, A., Rasmussen, L., Repellin, J. P., Rimoldi, A., Rushbrooke, J. G., Scampoli, P., Schacher, J., Singh, S. L., Stapnes, S., Stirling, A. V., Tovey, S. N., Unal, G., Valdata-Nappi, M., Vercesi, V., Weidberg, A. R., Wells, P. S., White, T. O., Wood, D. R., Wotton, S. A., Zaccone, H., and UA 2 Collaboration

Published
1990
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28. Measurement ofW andZ production cross sections at the CERN $$\bar p$$ p collider

Author

Alitti, J., Ansari, R., Ansorge, R. E., Bagnaia, P., Bareyre, P., Blaylock, G., Bonamy, P., Bonesini, M., Booth, C. N., Borer, K., Buskulic, D., Carboni, G., Cavalli, D., Cavasinni, V., Cenci, P., Chollet, J. C., Conta, C., Costa, G., Costantini, F., Crittenden, J., Dell'Acqua, A., DeLotto, B., DelPrete, T., DeWolf, R. S., DiLella, L., Egan, G. F., Einsweiler, K. F., Fayard, L., Federspiel, A., Ferrari, R., Fraternali, M., Froidevaux, D., Fumagalli, G., Gaillard, J. M., Gianotti, F., Gildemeister, O., Gössling, C., Goggi, V. G., Grünendahl, S., Hara, K., Hellman, S., Hugentobler, E., Hultqvist, K., Iacopini, E., Incandela, J., Jakobs, K., Jenni, P., Kluge, E. E., Kurz, N., Lami, S., Lariccia, P., Lefebvre, M., Linssen, L., Lisowski, B., Livan, M., Lubrano, P., Magneville, C., Mandelli, L., Mapelli, L., Mazzanti, M., Meier, K., Merkel, B., Meyer, J. P., Moniez, M., Moning, R., Morganti, M., Müller, L., Munday, D. J., Onions, C., Pal, T., Parker, M. A., Parrour, G., Pastore, F., Pennacchio, E., Pentney, J. M., Pepe, M., Perini, L., Petridou, C., Petroff, P., Plothow-Besch, H., Polesello, G., Poppleton, A., Punturo, M., Rasmussen, L., Repellin, J. P., Rimoldi, A., Rushbrooke, J. G., Scampoli, P., Schacher, J., Singh, S. L., Stapnes, S., Stirling, A. V., Tondini, F., Tovey, S. N., Tsesmelis, E., Valdata-Nappi, M., Vercesi, V., Weidberg, A. R., Wells, P. S., White, T. O., Wood, D. R., Wotton, S. A., Zaccone, H., and UA2 Collaboration

Published
1990
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29. DIRAC: A high resolution spectrometer for pionium detection

Author

Adeva, B., Afanasyev, L., Benayoun, M., Benelli, A., Berka, Z., Brekhovskikh, V., Caragheorgheopol, G., Cechak, T., Chiba, M., Cima, E., Constantinescu, S., Detraz, C., Dreossi, D., Drijard, D., Dudarev, A., Evangelou, I., Ferro-Luzzi, M., Gallas, M.V., Gerndt, J., Giacomich, R., Gianotti, P., Giardoni, M., Goldin, D., Gómez, F., Gorin, A., Gortchakov, O., Guaraldo, C., Hansroul, M., Iliescu, M., Zhabitsky, M., Karpukhin, V., Kluson, J., Kobayashi, M., Kokkas, P., Komarov, V., Kruglov, V., Kruglova, L., Kulikov, A., Kuptsov, A., Kurochkin, V., Kuroda, K.-I., Lamberto, A., Lanaro, A., Lapshin, V., Lednicky, R., Leruste, P., Levisandri, P., Lopez Aguera, A., Lucherini, V., Maki, T., Manthos, N., Manuilov, I., Montanet, L., Narjoux, J.-L., Nemenov, L., Nikitin, M., Núñez Pardo, T., Okada, K., Olchevskii, V., Orecchini, D., Pazos, A., Pentia, M., Penzo, A., Perreau, J.-M., Petrascu, C., Pló, M., Ponta, T., Pop, D., Rappazzo, G.F., Riazantsev, A., Rodriguez, J.M., Rodriguez Fernandez, A., Romero, A., Rykalin, V., Santamarina, C., Saborido, J., Schacher, J., Schuetz, Ch.P., Sidorov, A., Smolik, J., Steinacher, M., Takeutchi, F., Tarasov, A., Tauscher, L., Tobar, M.J., Triantis, F., Trusov, S., Utkin, V., Vázquez Doce, O., Vázquez, P., Vlachos, S., Yazkov, V., Yoshimura, Y., and Zrelov, P.

Published
2003
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30. First Measurement of a Long-Lived π^{+}π^{-} Atom Lifetime

Author

Adeva, B., Afanasyev, L., Anania, A., Aogaki, S., Benelli, A., Brekhovskikh, V., Cechak, T., Chiba, M., Chliapnikov, P. V., Doskarova, P., Drijard, D., Dudarev, A., Dumitriu, D., Fluerasu, D., Gorin, A., Gorchakov, O., Gritsay, K., Guaraldo, C., Gugiu, M., Hansroul, M., Hons, Z., Horikawa, S., Iwashita, Y., Karpukhin, V., Kluson, J., Kobayashi, M., Kruglov, V., Kruglova, L., Kulikov, A., Kulish, E., Lamberto, A., Lanaro, A., Lednicky, R., Mariñas, C., Martincik, J., Nemenov, L., Nikitin, M., Okada, K., Olchevskii, V., Ovsiannikov, V., Pentia, M., Penzo, A., Plo, M., Prusa, P., Rappazzo, G. F., Romero Vidal, A., Ryazantsev, A., Rykalin, V., Saborido, J., Schacher, J., Sidorov, A., Smolik, J., Takeutchi, F., Trojek, T., Trusov, S., Urban, T., Vrba, T., Yazkov, V., Yoshimura, Y., and Zrelov, P.

Abstract

The adapted DIRAC experiment at the CERN PS accelerator observed for the first time long-lived hydrogenlike π+π− atoms, produced by protons hitting a beryllium target. A part of these atoms crossed the gap of 96 mm between the target and a 2.1 μm thick platinum foil, in which most of them dissociated. Analyzing the observed number of atomic pairs, nAL=436−61+157|tot, the lifetime of the 2p state is found to be τ2p=(0.45−0.30+1.08|tot)×10−11 s, not contradicting the corresponding QED 2p state lifetime τ2pQED=1.17×10−11 s. This lifetime value is three orders of magnitude larger than our previously measured value of the π+π− atom ground state lifetime τ=(3.15−0.26+0.28|tot)×10−15 s. Further studies of long-lived π+π− atoms will allow us to measure energy differences between p and s atomic states and so to discriminate between the isoscalar and isotensor ππ scattering lengths with the aim to check QCD predictions.

Published
2018

31. Dirac experiment

Author

Gómez, F., Adeva, B., Afanasev, L., Benayoun, M., Brekhovskikh, V., Caragheorgheopol, G., Cechak, T., Chiba, M., Constantinescu, S., Doudarev, A., Dreossi, D., Drijard, D., Ferro-Luzzi, M., Gallas, M.V., Gerndt, J., Giacomich, R., Gianotti, P., Goldin, D., Gorin, A., Gortchakov, O., Guaraldo, C., Hansroul, M., Hosek, R., Iliescu, M., Jabitski, M., Kalinina, N., Karpoukhine, V., Kluson, J., Kobayashi, M., Kokkas, P., Komarov, V., Koulikov, A., Kouptsov, A., Krouglov, V., Krouglova, L., Kuroda, K.-I., Lanaro, A., Lapshine, V., Lednicky, R., Leruste, P., Levisandri, P., Lopez Aguera, A., Lucherini, V., Maki, T., Manuilov, I., Montanet, L., Narjoux, J.-L., Nemenov, L., Nikitin, M., Nunez Pardo, T., Okada, K., Olchevskii, V., Pazos, A., Pentia, M., Penzo, A., Perreau, J.-M., Petrascu, C., Plo, M., Ponta, T., Pop, D., Riazantsev, A., Rodriguez, J.M., Rodriguez Fernandez, A., Rykaline, V., Santamarina, C., Saborido, J., Schacher, J., Sidorov, A., Smolik, J., Takeutchi, F., Tarasov, A., Tauscher, L., Tobar, M.J., Trusov, S., Vazquez, P., Vlachos, S., Yazkov, V., Yoshimura, Y., and Zrelov, P.

Published
2001
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32. First measurement of a long-lived $��^+ ��^-$ atom lifetime

Author

Adeva, B., Afanasyev, L., Anania, A., Aogaki, S., Benelli, A., Brekhovskikh, V., Cechak, T., Chiba, M., Chliapnikov, P. V., Doskarova, P., Drijard, D., Dudarev, A., Dumitriu, D., Fluerasu, D., Gorin, A., Gorchakov, O., Gritsay, K., Guaraldo, C., Gugiu, M., Hansroul, M., Hons, Z., Horikawa, S., Iwashita, Y., Karpukhin, V., Kluson, J., Kobayashi, M., Kruglov, V., Kruglova, L., Kulikov, A., Kulish, E., Lamberto, A., Lanaro, A., Lednicky, R., Mari��as, C., Martincik, J., Nemenov, L., Nikitin, M., Okada, K., Olchevskii, V., Ovsiannikov, V., Pentia, M., Penzo, A., Plo, M., Prusa, P., Rappazzo, G. F., Vidal, A. Romero, Ryazantsev, A., Rykalin, V., Saborido, J., Schacher, J., Sidorov, A., Smolik, J., Takeutchi, F., Trojek, T., Trusov, S., Vrba, T., Yazkov, V., Yoshimura, Y., and Zrelov, P.

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

The adapted DIRAC experiment at the CERN PS accelerator observed for the first time long-lived hydrogen-like $��^+��^-$ atoms, produced by protons hitting a beryllium target. A part of these atoms crossed the gap of 96~mm and got broken up in the 2.1~\textmu{}m thick platinum foil. Analysing the observed number of atomic pairs, $n_A^L= \left.436^{+157}_{-61}\right|_\mathrm{tot}$, the lifetime of the 2$p$ state is found to be ${��_{2p}=(\left.0.45^{+1.08}_{-0.30}\right|_\mathrm{tot}) \cdot10^{-11}}$s, not contradicting the corresponding QED $2p$ state lifetime ${��_{2p}^\mathrm{QED}=1.17 \cdot 10^{-11}}$s. This lifetime value is three orders of magnitude larger than our previously measured value of the $��^+��^-$ atom ground state lifetime $��=(\left.3.15^{+0.28}_{-0.26}\right|_\mathrm{tot})\cdot 10^{-15}$s. Further studies of long-lived $��^+��^-$ atoms will allow to measure energy differences between $p$ and $s$ atomic states and so to determine $����$ scattering lengths with the aim to check QCD predictions., 7 pages, 8 figures

Published
2018
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33. First Measurement of a Long-Lived π+π− Atom Lifetime

Author

Adeva, B., primary, Afanasyev, L., additional, Anania, A., additional, Aogaki, S., additional, Benelli, A., additional, Brekhovskikh, V., additional, Cechak, T., additional, Chiba, M., additional, Chliapnikov, P. V., additional, Doskarova, P., additional, Drijard, D., additional, Dudarev, A., additional, Dumitriu, D., additional, Fluerasu, D., additional, Gorin, A., additional, Gorchakov, O., additional, Gritsay, K., additional, Guaraldo, C., additional, Gugiu, M., additional, Hansroul, M., additional, Hons, Z., additional, Horikawa, S., additional, Iwashita, Y., additional, Karpukhin, V., additional, Kluson, J., additional, Kobayashi, M., additional, Kruglov, V., additional, Kruglova, L., additional, Kulikov, A., additional, Kulish, E., additional, Lamberto, A., additional, Lanaro, A., additional, Lednicky, R., additional, Mariñas, C., additional, Martincik, J., additional, Nemenov, L., additional, Nikitin, M., additional, Okada, K., additional, Olchevskii, V., additional, Ovsiannikov, V., additional, Pentia, M., additional, Penzo, A., additional, Plo, M., additional, Prusa, P., additional, Rappazzo, G. F., additional, Romero Vidal, A., additional, Ryazantsev, A., additional, Rykalin, V., additional, Saborido, J., additional, Schacher, J., additional, Sidorov, A., additional, Smolik, J., additional, Takeutchi, F., additional, Trojek, T., additional, Trusov, S., additional, Urban, T., additional, Vrba, T., additional, Yazkov, V., additional, Yoshimura, Y., additional, and Zrelov, P., additional

Published
2019
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34. Measurement of the $��K$ atom lifetime and the $��K$ scattering length

Author

DIRAC Collaboration, Adeva, B., Afanasyev, L., Allkofer, Y., Amsler, C., Anania, A., Aogaki, S., Benelli, A., Brekhovskikh, V., Cechak, T., Chiba, M., Chliapnikov, P., Drijard, D., Dudarev, A., Dumitriu, D., Federicova, P., Fluerasu, D., Gorin, A., Gorchakov, O., Gritsay, K., Guaraldo, C., Gugiu, M., Hansroul, M., Hons, Z., Horikawa, S., Iwashita, Y., Karpukhin, V., Kluson, J., Kobayashi, M., Kruglov, V., Kruglova, L., Kulikov, A., Kulish, E., Kuptsov, A., Lamberto, A., Lanaro, A., Lednicky, R., Marinas, C., Martincik, J., Nemenov, L., Nikitin, M., Okada, K., Olchevskii, V., Pentia, M., Penzo, A., Plo, M., Prusa, P., Rappazzo, G., Vidal, A. Romero, Ryazantsev, A., Rykalin, V., Saborido, J., Schacher, J., Sidorov, A., Smolik, J., Takeutchi, F., Tauscher, L., Trojek, T., Trusov, S., Urban, T., Vrba, T., Yazkov, V., Yoshimura, Y., Zhabitsky, M., and Zrelov, P.

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

After having announced the statistically significant observation (5.6~$��$) of the new exotic $��K$ atom, the DIRAC experiment at the CERN proton synchrotron presents the measurement of the corresponding atom lifetime, based on the full $��K$ data sample: $��= (5.5^{+5.0}_{-2.8}) \cdot 10^{-15}s$. By means of a precise relation ($, 18 pages, 17 figures

Published
2017
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35. First measurement of the π+π− atom lifetime

Author

Adeva, B., Afanasyev, L., Benayoun, M., Benelli, A., Berka, Z., Brekhovskikh, V., Caragheorgheopol, G., Cechak, T., Chiba, M., Constantinescu, S., Detraz, C., Dreossi, D., Drijard, D., Dudarev, A., Evangelou, I., Ferro-Luzzi, M., Gallas, M.V., Gerndt, J., Giacomich, R., Gianotti, P., Goldin, D., Gómez, F., Gorin, A., Gorchakov, O., Guaraldo, C., Hansroul, M., Hosek, R., Iliescu, M., Karpukhin, V., Kluson, J., Kobayashi, M., Kokkas, P., Komarov, V., Kruglov, V., Kruglova, L., Kulikov, A., Kuptsov, A., Kurochkin, I., Kuroda, K.-I., Lamberto, A., Lanaro, A., Lapshin, V., Lednicky, R., Leruste, P., Levi Sandri, P., Lopez Aguera, A., Lucherini, V., Maki, T., Manthos, N., Manuilov, I., Montanet, L., Narjoux, J.-L., Nemenov, L., Nikitin, M., Núñez Pardo, T., Okada, K., Olchevskii, V., Pazos, A., Pentia, M., Penzo, A., Perreau, J.-M., Petrascu, C., Pló, M., Ponta, T., Pop, D., Rappazzo, G.F., Rodriguez Fernandez, A., Romero, A., Ryazantsev, A., Rykalin, V., Santamarina, C., Saborido, J., Schacher, J., Schuetz, Ch.P., Sidorov, A., Smolik, J., Takeutchi, F., Tarasov, A., Tauscher, L., Tobar, M.J., Trusov, S., Utkin, V., Vázquez Doce, O., Vázquez, P., Vlachos, S., Yazkov, V., Yoshimura, Y., Zhabitsky, M., and Zrelov, P.

Subjects
Nuclear and High Energy Physics
Published
2005
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37. First $��K$ atom lifetime and $��K$ scattering length measurements

Author

Adeva, B., Afanasyev, L., Allkofer, Y., Amsler, C., Anania, A., Aogaki, S., Benelli, A., Brekhovskikh, V., Cechak, T., Chiba, M., Chliapnikov, P., Ciocarlan, C., Constantinescu, S., Doskarova, P., Drijard, D., Dudarev, A., Duma, M., Dumitriu, D., Fluerasu, D., Gorin, A., Gorchakov, O., Gritsay, K., Guaraldo, C., Gugiu, M., Hansroul, M., Hons, Z., Horikawa, S., Iwashita, Y., Karpukhin, V., Kluson, J., Kobayashi, M., Kruglov, V., Kruglova, L., Kulikov, A., Kulish, E., Kuptsov, A., Lamberto, A., Lanaro, A., Lednicky, R., Mari��as, C., Martincik, J., Nemenov, L., Nikitin, M., Okada, K., Olchevskii, V., Pentia, M., Penzo, A., Plo, M., Ponta, T., Prusa, P., Rappazzo, G., Vidal, A. Romero, Ryazantsev, A., Rykalin, V., Schacher, J., Sidorov, A., Smolik, J., Sugimoto, S., Takeutchi, F., Tauscher, L., Trojek, T., Trusov, S., Urban, T., Vrba, T., Yazkov, V., Yoshimura, Y., Zhabitsky, M., and Zrelov, P.

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

The results of a search for hydrogen-like atoms consisting of $��^{\mp}K^{\pm}$ mesons are presented. Evidence for $��K$ atom production by 24 GeV/c protons from CERN PS interacting with a nickel target has been seen in terms of characteristic $��K$ pairs from their breakup in the same target ($178 \pm 49$) and from Coulomb final state interaction ($653 \pm 42$). Using these results the analysis yields a first value for the $��K$ atom lifetime of $��=(2.5_{-1.8}^{+3.0})$ fs and a first model-independent measurement of the S-wave isospin-odd $��K$ scattering length $\left|a_0^-\right|=\frac{1}{3}\left|a_{1/2}-a_{3/2}\right|= \left(0.11_{-0.04}^{+0.09} \right)M_��^{-1}$ ($a_I$ for isospin $I$)., 14 pages, 8 figures

Published
2014
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38. Jet measures and hadronic event shapes at the CERN $$\bar p$$ p collider

Author

Ansari, R., Bagnaia, P., Banner, M., Battiston, R., Bernlöhr, K., Booth, C., Borer, K., Borghini, M., Carboni, G., Cavasinni, V., Cenci, P., Chollet, J. -C., Clark, A. G., Conta, C., Costantini, F., Darriulat, P., De Lotto, B., Del Prete, T., DiLella, L., Dines-Hansen, J., Einsweiler, K., Fayard, L., Ferrari, R., Fraternali, M., Froidevaux, D., Gaillard, J. -M., Gildemeister, O., Goggi, V. G., Gössling, C., Hahn, B., Hänni, H., Hansen, J. R., Hansen, P., Hara, K., Harnew, N., Hugentobler, E., Iacopini, E., Iconomidou-Fayard, L., Jakobs, K., Jenni, P., Kluge, E. E., Kofoed-Hansen, O., Lançon, E., Lariccia, P., Livan, M., Loucatos, S., Madsen, B., Mansoulié, B., Mantovani, G. C., Mapelli, L., Meier, K., Merkel, B., Möllerud, R., Moniez, M., Moning, R., Morganti, M., Onions, C., Parker, M. A., Parrour, G., Pastore, F., Pepe, M., Petridou, Ch., Plothow-Besch, H., Polverel, M., Rasmussen, L., Repellin, J. -P., Rimoldi, A., Roussarie, A., Ruhlmann, V., Sauvage, G., Schacher, J., Stapnes, S., Stocker, F., Swartz, M., Teiger, J., Tsang, W. Y., Valdata-Nappi, M., Vercesi, V., Weidberg, A. R., Wunsch, M., Zaccone, H., and UA 2 Collaboration

Published
1987
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40. Buchbesprechungen

Author

Rott, N., Schneebeli, H. R., Hässig, K., Läuchli, H., Zwahlen, Bruno, Schaufelberger, W., Mihăilescu, P., Amann, H., Schacher, J., Straumann, N., Affolter, Klaus, Ammann, U., Marti, J., Engeler, E., Gyr, A., and Melchior, H.

Published
1982
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42. Buchbesprechungen

Author

Rössler, M., Schacher, J., Schneebeli, H., Lüthi, H. R., Hazeghi, K., Bucher, W., Tschudi, Theo, Engeler, E., Schüler, Georges, Balmer, J., Batschelet, E., and Minkowski, Peter

Published
1978
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43. Inclusive particle production in the transverse momentum range between 0.25 and 40 GeV/c at the CERN $$Sp\bar pS$$ collider

Author

Banner, M., Bloch, Ph., Bonaudi, F., Borer, K., Borghini, M., Chollet, J. C., Clark, A. G., Conta, C., Darriulat, P., Di Lella, L., Hansen, J. Dines, Dorsaz, P. A., Fayard, L., Fraternali, M., Froidevaux, D., Gaillard, J. M., Gildemeister, O., Goggi, V. G., Hahn, B., Hänni, H., Hansen, J. R., Hansen, P., Himel, T., Hungerbühler, V., Jenni, P., Kofoed-Hansen, O., Lançon, E., Livan, M., Loucatos, S., Madsen, B., Mani, P., Mansoulié, B., Mantovani, G. C., Mapelli, L., Merkel, B., Møllerud, R., Onions, C., Parrour, G., Pastore, F., Plothow-Besch, H., Polverel, M., Repellin, J. P., Rimoldi, A., Rothenberg, A., Roussarie, A., Sauvage, G., Schacher, J., Siegrist, J. L., Stocker, F., Teiger, J., Vercesi, V., Weidberg, A., Zaccone, H., Zeller, W., and UA2 Collaboration

Published
1985
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45. A study of three-jet events at the CERN $$\bar pp$$ collider

Author

Appel, J. A., Bagnaia, P., Banner, M., Battiston, R., Bernlöhr, K., Borer, K., Borghini, M., Bürger, J., Carboni, G., Cavasinni, V., Cenci, P., Chollet, J. -C., Clark, A. G., Codino, A., Conta, C., Darriulat, P., De Lotto, B., Del Prete, T., Di Lella, L., Dines-Hansen, J., Einsweiler, K., Engelmann, R., Fayard, L., Fraternali, M., Froidevaux, D., Gaillard, J. -M., Gildemeister, O., Goggi, V. G., Gössling, C., Hahn, B., Hänni, H., Hansen, J. R., Hansen, P., Harnew, N., Himel, T., Iconomidou-Fayard, L., Jakobs, K., Jenni, P., Kluge, E. E., Kofoed-Hansen, O., Lançon, E., Livan, M., Loucatos, S., Madsen, B., Mani, P., Mansoulié, B., Mantovani, G. C., Mapelli, L., Meier, K., Merkel, B., Mollerud, R., Moniez, M., Moning, R., Morganti, M., Onions, C., Parker, M. A., Parrour, G., Pastore, F., Pepe, M., Plothow-Besch, H., Polverel, M., Repellin, J. -P., Rimoldi, A., Rothenberg, A. F., Roussarie, A., Ruhlmann, V., Sauvage, G., Schacher, J., Schlötelburg, M., Stocker, F., Swartz, M., Teiger, J., Tovey, S. N., Tsang, W. Y., Valdata-Nappi, M., Vercesi, V., Weidberg, A. R., Wunsch, M., Zaccone, H., and The UA2 Collaboration

Published
1986
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46. Measurement ofW ± andZ 0 properties at the CERN $$\bar pp$$ p collider

Author

Appel, J. A., Bagnaia, P., Banner, M., Battiston, R., Bernlöhr, K., Borer, K., Borghini, M., Carboni, G., Cavasinni, V., Cenci, P., Chollet, J. -C., Clark, A. G., Codino, A., Conta, C., Darriulat, P., De Lotto, B., Del Prete, T., Di Lella, L., Dines-Hansen, J., Einsweiler, K., Engelmann, R., Fayard, L., Fraternali, M., Froidevaux, D., Gaillard, J. -M., Gildemeister, O., Goggi, V. G., Gössling, C., Hahn, B., Hänni, H., Hansen, J. R., Hansen, P., Harnew, N., Himel, T., Iconomidou-Fayard, L., Jakobs, K., Jenni, P., Kluge, E. E., Kofoed-Hansen, O., Lançon, E., Livan, M., Loucatos, S., Madsen, B., Mani, P., Mansoulié, B., Mantovani, G. C., Mapelli, L., Meier, K., Merkel, B., Möllerud, R., Moniez, M., Moning, R., Morganti, M., Nilsson, B., Onions, C., Parker, M. A., Parrour, G., Pastore, F., Pepe, M., Plothow-Besch, H., Polverel, M., Putzer, A., Repellin, J. -P., Rothenberg, A. F., Roussarie, A., Ruhlmann, V., Sauvage, G., Schacher, J., Schlötelburg, M., Stocker, F., Swartz, M., Teiger, J., Tittel, K., Tovey, S. N., Tsang, W. Y., Valdata-Nappi, M., Vercesi, V., Weidberg, A. R., Wunsch, M., Zaccone, H., and UA2 Collaboration

Published
1986
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47. A study of high transverse momentum electrons produced in $$\bar pp$$ collisions at 540 GeV

Author

Bagnaia, P., Banner, M., Battiston, R., Bloch, Ph., Bonaudi, F., Borer, K., Borghini, M., Burger, J., Cenci, P., Chollet, J. -C., Clark, A. G., Conta, C., Darriulat, P., Di Lella, L., Dines-Hansch, J., Dorsaz, P. A., Engelmann, R., Fayard, L., Fraternali, M., Froidevaux, D., Fumagalli, G., Gaillard, J. -M., Gildemeister, O., Goggi, V. G., Gössling, C., Hahn, B., Hänni, H., Hansen, J. R., Hansen, P., Harnew, N., Himel, T., Hungerbühler, V., Jenni, P., Kofoed-Hansen, O., Lançon, E., Livan, M., Loucatos, S., Madsen, B., Mani, P., Mansoulié, B., Mantovani, G. C., Mapelli, L., Merkel, B., Möllerud, R., Nilsson, B., Onions, C., Parrour, G., Pastore, F., Plothow-Besch, H., Polverel, M., Repellin, J. -P., Rimoldi, A., Rothenberg, A., Roussarie, A., Sauvage, G., Schacher, J., Siegrist, J. L., Stimpfl, G., Stocker, F., Swartz, M., Teiger, J., Tovey, S., Vercesi, V., Weidberg, W. R., Zaccone, H., Zakrzewski, J. A., Zeller, W., and The AU2 Collaboration

Published
1984
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48. Measurement of production and properties of jets at the CERN $$\bar pp$$ collider

Author

Bagnaia, P., Banner, M., Battiston, R., Bloch, Ph., Bonaudi, F., Borer, K., Borghini, M., Chollet, J. -C., Clark, A. G., Conta, C., Darriulat, P., Di Lella, L., Dines-Hansen, J., Dorsaz, P. -A., Fayard, L., Fraternali, M., Froidevaux, D., Fumagalli, G., Gaillard, J. -M., Gildemeister, O., Goggi, V. G., Hahn, B., Hänni, H., Hansen, J. R., Hansen, P., Himel, T., Hungerbühler, V., Jenni, P., Kofoed-Hansen, O., Lançon, E., Livan, M., Loucatos, S., Madsen, B., Mani, P., Mansoulié, B., Mantovani, G. C., Mapelli, L., Merkel, B., Møllerud, R., Onions, C., Parrour, G., Psstore, F., Plothow-Besch, H., Polverel, M., Repellin, J. -P., Rimoldi, A., Rothenberg, A., Roussarie, A., Sauvage, G., Schacher, J., Siegrist, J. L., Steiner, H. M., Stimpfl, G., Stocker, F., Teiger, J., Vercesi, V., Weidberg, A., Zaccone, H., Zeller, W., and UA2 Collaboration

Published
1983
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50. Search for Long-Lived States of $\pi^+\pi^-$ Atoms : Addendum to the DIRAC Proposal

Author

Adeva, B, Afanasyev, L, Anania, A, Aogaki, S, Augsten, K, Batyuk, P, Benelli, A, Brekhovskikh, V, Cechak, T, Chiba, M, Ciortea, C, Curceanu, C, Doskarova, P, Dudarev, A, Dumitriu, D, Drijard, D, Fluerasu, D, Gortchakov, O, Gritsay, K, Guaraldo, C, Gugiu, M, Hansroul, M, Hosek, R, Hons, Z, Iwashita, Y, Karpukhin, V, Kluson, J, Kobayashi, M, Kruglov, V, Kruglova, L, Kulikov, A, Kulish, E, Kuptsov, A, Lamberto, A, Lednicky, R, Martincik, J, Nemenov, L, Nikitin, M, Okada, K, Pentia, M, Plo, M, Prusa, P, Rappazzo, G, Ryazantsev, A, Romero, A, Ronzhin, V, Rykalin, V, Saborido, J, Schacher, J, Shlyapnikov, P, Smolik, J, Takeutchi, F, Trojek, T, Urban, T, Vrba, T, Vazquez, P, Yazkov, V, Yoshimura, Y, Zhabitsky, M, and Zrelov, P

Subjects
Detectors and Experimental Techniques
Abstract

The proposed experiment is a further development of the DIRAC experiment already running at CERN PS. The observation of long-lived (metastable) states of $\pi^+\pi^-$ atoms ($A_{2\pi}$) will be performed with the same setup. This observation opens a possibility to measure the energy difference between $ns$ and $np$ states and to determine the value of the combination $2a_0+a_2$ of S-wave $\pi\pi$ scattering lengths in a model-independent way. In combination with the $A_{2\pi}$ lifetime measurement providing the value $|a_0-a_2|$ DIRAC is in the position to get $a_0$ and $a_2$ separately on the basis of $A_{2\pi}$ data only.

Published
2012

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