Observation of the Radiative Decays of ϒ(1S) to χ_{c1}.

/ Authors

P. Katrenko, I. Adachi, H. Aihara, S. Al Said, D. Asner, T. Aushev, I. Badhrees, S. Bahinipati, P. Behera, C. Beleño

and 160 more authors

J. Bennett, V. Bhardwaj, B. Bhuyan, J. Biswal, A. Bobrov, G. Bonvicini, M. Bračko, M. Campajola, L. Cao, D. Červenkov, V. Chekelian, A. Chen, B. Cheon, K. Chilikin, H. E. Cho, K. Cho, S. Choi, Y. Choi, S. Choudhury, D. Cinabro, S. Cunliffe, F. Di Capua, S. Di Carlo, Z. Doležal, T. Dong, S. Eidelman, D. Epifanov, J. Fast, B. Fulsom, R. Garg, V. Gaur, N. Gabyshev, A. Garmash, A. Giri, P. Goldenzweig, B. Golob, O. Grzymkowska, O. Hartbrich, K. Hayasaka, H. Hayashii, W. Hou, T. Iijima, K. Inami, A. Ishikawa, R. Itoh, M. Iwasaki, Y. Iwasaki, W. Jacobs, H. Jeon, S. Jia, Y. Jin, D. Joffe, K. Joo, G. Karyan, H. Kichimi, D. Y. Kim, K. T. Kim, S. H. Kim, K. Kinoshita, P. Kodys, S. Korpar, P. Križan, R. Kroeger, T. Kuhr, I. Lee, S. C. Lee, P. Lewis, Y. B. Li, L. Li Gioi, J. Libby, Kilian Adriano Lieret, C. MacQueen, M. Masuda, T. Matsuda, D. Matvienko, M. Merola, K. Miyabayashi, H. Miyata, R. Mizuk, G. Mohanty, T. Moon, Takashi Mori, R. Mussa, E. Nakano, T. Nakano, M. Nakao, M. Nayak, N. Nisar, S. Nishida, K. Nishimura, H. Ono, Y. Onuki, P. Oskin, P. Pakhlov, G. Pakhlova, T. Pang, S. Pardi, C. W. Park, H. Park, S. Park, S. Paul, T. Pedlar, R. Pestotnik, L. Piilonen, V. Popov, E. Prencipe, M. Prim, M. Ritter, A. Rostomyan, N. Rout, G. Russo, D. Sahoo, Y. Sakai, S. Sandilya, T. Sanuki, V. Savinov, O. Schneider, G. Schnell, J. Schueler, C. Schwanda, Y. Seino, K. Senyo, M. Sevior, C. Shen, J. Shiu, E. Solovieva, M. Starič, Z. Stottler, T. Sumiyoshi, W. Sutcliffe, M. Takizawa, U. Tamponi, K. Tanida, F. Tenchini, K. Trabelsi, M. Uchida, S. Uehara, T. Uglov, Y. Unno, S. Uno, P. Urquijo, Y. Usov, R. van Tonder, G. Varner, A. Vossen, B. Wang, C. H. Wang, M. Wang, P. Wang, X. L. Wang, E. Won, S. B. Yang, H. Ye, J. Yelton, J. H. Yin, C. Yuan, Y. Yusa, Z. P. Zhang, V. Zhilich, V. Zhukova

/ Abstract

We report the first observation of the radiative decay of the ϒ(1S) into a charmonium state. The significance of the observed signal of ϒ(1S)→γχ_{c1} is 6.3 standard deviations including systematics. The branching fraction is calculated to be B[ϒ(1S)→γχ_{c1}]=[4.7_{-1.8}^{+2.4}(stat)_{-0.5}^{+0.4}(sys)×10^{-5}]. We also searched for ϒ(1S) radiative decays into χ_{c0,2} and η_{c}(1S,2S), and set upper limits on their branching fractions. These results are obtained from a 24.9 fb^{-1} data sample collected with the Belle detector at the KEKB asymmetric-energy e^{+}e^{-} collider at a center-of-mass energy equal to the ϒ(2S) mass using ϒ(1S) tagging by the ϒ(2S)→ϒ(1S)π^{+}π^{-} transitions.

Journal: Physical review letters

DOI: 10.1103/PhysRevLett.124.122001