Spin Dependence of η Meson Production in Proton-Proton Collisions Close to Threshold

P. Adlarson, W. Augustyniak, W. Bardan, M. Bashkanov, S. D. Bass, F. S. Bergmann, M. Berłowski, A. Bondar, M. Büscher, H. Calén, I. Ciepał, H. Clement, E. Czerwiński, K. Demmich, R. Engels, A. Erven, W. Erven, W. Eyrich, P. Fedorets, K. FöhlK. Fransson, F. Goldenbaum, A. Goswami, K. Grigoryev, C. O. Gullström, L. Heijkenskjöld, V. Hejny, N. Hüsken, L. Jarczyk, T. Johansson, B. Kamys, G. Kemmerling, G. Khatri, A. Khoukaz, O. Khreptak, D. A. Kirillov, S. Kistryn, H. Kleines, B. Kłos, W. Krzemień, P. Kulessa, A. Kupść, A. Kuzmin, K. Lalwani, D. Lersch, B. Lorentz, A. Magiera, R. Maier, P. Marciniewski, B. Shwartz, WASA-at-COSY Collaboration

Результат исследования: Научные публикации в периодических изданияхстатьярецензирование

2 Цитирования (Scopus)


Taking advantage of the high acceptance and axial symmetry of the WASA-at-COSY detector, and the high polarization degree of the proton beam of COSY, the reaction p→p→ppη has been measured close to threshold to explore the analyzing power Ay. The angular distribution of Ay is determined with the precision improved by more than 1 order of magnitude with respect to previous results, allowing a first accurate comparison with theoretical predictions. The determined analyzing power is consistent with zero for an excess energy of Q=15 MeV, signaling s-wave production with no evidence for higher partial waves. At Q=72 MeV the data reveal strong interference of Ps and Pp partial waves and cancellation of (Pp)2 and Ss∗Sd contributions. These results rule out the presently available theoretical predictions for the production mechanism of the η meson.

Язык оригиналаанглийский
Номер статьи022002
Число страниц6
ЖурналPhysical Review Letters
Номер выпуска2
СостояниеОпубликовано - 8 янв 2018

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