Observation of $\Upsilon(2S)\to\gamma \eta_{b}(1S)$ decay
Creators: name: Fulsom, B. G.
name: Pedlar, T. K.
name: Adachi, I.
name: Aihara, H.
name: Al Said, S.
name: Asner, D. M.
name: Atmacan, H.
name: Aulchenko, V.
name: Aushev, T.
name: Ayad, R.
name: Babu, V.
name: Badhrees, I.
name: Bakich, A. M.
name: Bansal, V.
name: Behera, P.
name: Beleño, C.
name: Berger, M.
name: Bhardwaj, V.
name: Bhuyan, B.
name: Bilka, T.
name: Biswal, J.
name: Bondar, A.
name: Bonvicini, G.
name: Bozek, A.
name: Bračko, M.
name: Browder, T. E.
name: Cao, L.
name: Červenkov, D.
name: Chekelian, V.
name: Chen, A.
name: Cheon, B. G.
name: Chilikin, K.
name: Cho, K.
name: Choi, S.-K.
name: Choi, Y.
name: Choudhury, S.
name: Cinabro, D.
name: Cunliffe, S.
name: Dash, N.
name: Di Carlo, S.
name: Dingfelder, J.
name: Doležal, Z.
name: Dong, T. V.
name: Drásal, Z.
name: Eidelman, S.
name: Epifanov, D.
name: Fast, J. E.
name: Ferber, T.
name: Garg, R.
name: Gaur, V.
name: Gabyshev, N.
name: Garmash, A.
name: Gelb, M.
name: Giri, A.
name: Goldenzweig, P.
name: Guido, E.
name: Haba, J.
name: Hayasaka, K.
name: Hayashii, H.
name: Hirose, S.
name: Hou, W.-S.
name: Iijima, T.
name: Inami, K.
name: Inguglia, G.
name: Ishikawa, A.
name: Itoh, R.
name: Iwasaki, M.
name: Iwasaki, Y.
name: Jacobs, W. W.
name: Jeon, H. B.
name: Jia, S.
name: Jin, Y.
name: Joffe, D.
name: Joo, K. K.
name: Julius, T.
name: Kawasaki, T.
name: Kichimi, H.
name: Kiesling, C.
name: Kim, D. Y.
name: Kim, H. J.
name: Kim, J. B.
name: Kim, K. T.
name: Kim, S. H.
name: Kinoshita, K.
name: Kodyš, P.
name: Korpar, S.
name: Kotchetkov, D.
name: Križan, P.
name: Kroeger, R.
name: Krokovny, P.
name: Kuhr, T.
name: Kulasiri, R.
name: Kuzmin, A.
name: Kwon, Y.-J.
name: Lange, J. S.
name: Lee, I. S.
name: Lee, S. C.
name: Li, L. K.
name: Li, Y. B.
name: Li Gioi, L.
name: Libby, J.
name: Liventsev, D.
name: Lubej, M.
name: Luo, T.
name: Masuda, M.
name: Matsuda, T.
name: Matvienko, D.
name: Merola, M.
name: Miyabayashi, K.
name: Miyata, H.
name: Mizuk, R.
name: Mohanty, G. B.
name: Moon, H. K.
name: Mori, T.
name: Mussa, R.
name: Nakao, M.
name: Nanut, T.
name: Nath, K. J.
name: Natkaniec, Z.
name: Nayak, M.
name: Niiyama, M.
name: Nisar, N. K.
name: Nishida, S.
name: Ogawa, S.
name: Okuno, S.
name: Ono, H.
name: Pakhlov, P.
name: Pakhlova, G.
name: Pal, B.
name: Pardi, S.
name: Park, H.
name: Paul, S.
name: Pestotnik, R.
name: Piilonen, L. E.
name: Popov, V.
name: Prencipe, E.
name: Rabusov, A.
name: Ritter, M.
name: Rostomyan, A.
name: Russo, G.
name: Sakai, Y.
name: Salehi, M.
name: Sandilya, S.
name: Santelj, L.
name: Sanuki, T.
name: Savinov, V.
name: Schneider, O.
name: Schnell, G.
name: Schwanda, C.
name: Seino, Y.
name: Senyo, K.
name: Sevior, M. E.
name: Shebalin, V.
name: Shen, C. P.
name: Shibata, T.-A.
name: Shiu, J.-G.
name: Shwartz, B.
name: Simon, F.
name: Singh, J. B.
name: Sokolov, A.
name: Solovieva, E.
name: Starič, M.
name: Strube, J. F.
name: Sumihama, M.
name: Sumisawa, K.
name: Sumiyoshi, T.
name: Sutcliffe, W.
name: Takizawa, M.
name: Tamponi, U.
name: Tanida, K.
name: Tenchini, F.
name: Uchida, M.
name: Uglov, T.
name: Unno, Y.
name: Uno, S.
name: Urquijo, P.
name: Vahsen, S. E.
name: Van Hulse, C.
name: Van Tonder, R.
name: Varner, G.
name: Vinokurova, A.
name: Vorobyev, V.
name: Vossen, A.
name: Wang, B.
name: Wang, C. H.
name: Wang, P.
name: Wang, X. L.
name: Watanabe, M.
name: Watanuki, S.
name: Widmann, E.
name: Won, E.
name: Ye, H.
name: Yin, J. H.
name: Yuan, C. Z.
name: Zhang, Z. P.
name: Zhilich, V.
name: Zhukova, V.
name: Zhulanov, V.
name: Zupanc, A.
Publisher: name: Deutsches Elektronen-Synchrotron, DESY, Hamburg
Year: 2018
Subjects: electron positron: annihilation
electron positron: colliding beams
photon: spectrum
Upsilon(10020): electroproduction
Upsilon(10020): radiative decay
eta/b: electroproduction
eta/b: mass: measured
Upsilon(10020): branching ratio: measured
statistical
BELLE
KEK-B
experimental results
Upsilon(10020) --&gt; eta/b photon

description: We report the observation of $\Upsilon(2S)\to\gamma\eta_{b}(1S)$ decay based on analysis of the inclusive photon spectrum of $24.7$ fb$^{-1}$ of $e^+ e^-$ collisions at the $\Upsilon(2S)$ center-of-mass energy collected with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. We measure a branching fraction of $\mathcal{B}(\Upsilon(2S)\to\gamma\eta_{b}(1S))=(6.1^{+0.6+0.9}_{-0.7-0.5})\times 10^{-4}$, and derive an $\eta_{b}(1S)$ mass of $9394.8^{+2.7+4.5}_{-3.1-2.7}$ MeV/$c^{2}$, where the uncertainties are statistical and systematic, respectively. The significance of our measurement is greater than 7 standard deviations, constituting the first observation of this decay mode.