Observation of the Radiative Decays of Upsilon(1S) to chi(c1)

Katrenko, P.; Adachi, I.; Aihara, H.; Al Said, S.; Asner, D. M.; Aushev, T.; Badhrees, I.; Bahinipati, S.; Behera, P.; Beleno, C.; Bennett, J.; Bhardwaj, V.; Bhuyan, B.; Biswal, J.; Bobrov, A.; Bonvicini, G.; Bracko, M.; Campajola, M.; Cao, L.; Cervenkov, D.; Chekelian, V.; Chen, A.; Cheon, B. G.; Chilikin, K.; Cho, H. E.; Cho, K.; Choi, S. K.; Choi, Y.; Choudhury, S.; Cinabro, D.; Cunliffe, S.; Di Capua, F.; Di Carlo, S.; Dolezal, Z.; Dong, T. V.; Eidelman, S.; Epifanov, D.; Fast, J. E.; Fulsom, B. G.; Garg, R.; Gaur, V; Gabyshev, N.; Garmash, A.; Giri, A.; Goldenzweig, P.; Golob, B.; Grzymkowska, O.; Hartbrich, O.; Hayasaka, K.; Hayashii, H.; Hou, W. S.; Iijima, T.; Inami, K.; Ishikawa, A.; Itoh, R.; Iwasaki, M.; Iwasaki, Y.; Jacobs, W. W.; Jeon, H. B.; Jia, S.; Jin, Y.; Joffe, D.; Joo, K. K.; Karyan, G.; Kichimi, H.; Kim, D. Y.; Kim, K. T.; Kim, S. H.; Kinoshita, K.; Kodys, P.; Korpar, S.; Krizan, P.; Kroeger, R.; Kuhr, T.; Lee, I. S.; Lee, S. C.; Lewis, P.; Li, Y. B.; Li Gioi, L.; Libby, J.; Lieret, K.; MacQueen, C.; Masuda, M.; Matsuda, T.; Matvienko, D.; Merola, M.; Miyabayashi, K.; Miyata, H.; Mizuk, R.; Mohanty, G. B.; Moon, T. J.; Mori, T.; Mussa, R.; Nakano, E.; Nakano, T.; Nakao, M.; Nayak, M.; Nisar, N. K.; Nishida, S.; Nishimura, K.; Ono, H.; Onuki, Y.; Oskin, P.; Pakhlov, P.; Pakhlova, G.; Pang, T.; Pardi, S.; Park, C. W.; Park, H.; Park, S. H.; Paul, S.; Pedlar, T. K.; Pestotnik, R.; Piilonen, L. E.; Popov, V.; Prencipe, E.; Prim, M. T.; Ritter, M.; Rostomyan, A.; Rout, N.; Russo, G.; Sahoo, D.; Sakai, Y.; Sandilya, S.; Sanuki, T.; Savinov, V.; Schneider, O.; Schnell, G.; Schueler, J.; Schwanda, C.; Seino, Y.; Senyo, K.; Sevior, M. E.; Shen, C. P.; Shiu, J. G.; Solovieva, E.; Staric, M.; Stottler, Z. S.; Sumiyoshi, T.; Sutcliffe, W.; Takizawa, M.; Tamponi, U.; Tanida, K.; Tenchini, F.; Trabelsi, K.; Uchida, M.; Uehara, S.; Uglov, T.; Unno, Y.; Uno, S.; Urquijo, P.; Usov, Y.; Tonder, R. van; Varner, G.; Vossen, A.; Wang, B.; Wang, C. H.; Wang, M. Z.; Wang, P.; Wang, X. L.; Won, E.; Yang, S. B.; Ye, H.; Yelton, J.; Yin, J. H.; Yuan, C. Z.; Yusa, Y.; Zhang, Z. P.; Zhilich, V.; Zhukova, V. (2020): Observation of the Radiative Decays of Upsilon(1S) to chi(c1). In: Physical Review Letters, Vol. 124, No. 12, 122001

Abstract

We report the first observation of the radiative decay of the Upsilon(1S) into a charmonium state. The significance of the observed signal of Upsilon(1S) -> gamma chi(c1) is 6.3 standard deviations including systematics. The branching fraction is calculated to be B[Upsilon(1S) -> gamma chi(c1)] = [4.7(-1.8)(+2.4) (stat)(-0.5)(+0.4) (sys) x 10(-5)]. We also searched for Upsilon(1S) radiative decays into chi(c0.2) and eta(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 Upsilon(2S) mass using Upsilon(1S) tagging by the Upsilon(2S) -> Upsilon(1S)pi(+)pi(-) transitions.

• Item Type: Journal article
• Faculties: Physics
• Subjects: 500 Science > 530 Physics
• ISSN: 0031-9007
• Language: English