Study of the Hadronic Transitions $Υ$(2S)$\rightarrow (η,π^0)Υ$(1S) at Belle
Creators: name: Belle Collaboration
name: Tamponi, U.
name: Mussa, R.
name: Adachi, I.
name: Aihara, H.
name: Asner, D. M.
name: Aulchenko, V.
name: Aushev, T.
name: Bakich, A. M.
name: Barrett, M.
name: Bhuyan, B.
name: Bondar, A.
name: Bozek, A.
name: Bra\v, M.
name: Browder, T. E.
name: Chen, A.
name: Chen, P.
name: Cheon, B. G.
name: Chilikin, K.
name: Cho, I. -S.
name: Cho, K.
name: Choi, Y.
name: Dalseno, J.
name: Dole\v, Z.
name: Drásal, Z.
name: Dutta, D.
name: Eidelman, S.
name: Epifanov, D.
name: Esen, S.
name: Farhat, H.
name: Fast, J. E.
name: Frey, A.
name: Gaur, V.
name: Gillard, R.
name: Goh, Y. M.
name: Golob, B.
name: Hayasaka, K.
name: Horii, Y.
name: Hoshi, Y.
name: Hyun, H. J.
name: Iijima, T.
name: Ishikawa, A.
name: Iwasaki, Y.
name: Jaegle, I.
name: Kang, J. H.
name: Kawasaki, T.
name: Kim, H. O.
name: Kim, J. H.
name: Kim, K. T.
name: Kim, M. J.
name: Kim, Y. J.
name: Klucar, J.
name: Ko, B. R.
name: Kody\v, P.
name: Korpar, S.
name: Kouzes, R. T.
name: Kri\v, P.
name: Krokovny, P.
name: Kumita, T.
name: Kuzmin, A.
name: Lee, S. -H.
name: Li, Y.
name: Liu, C.
name: Liu, Y.
name: Liu, Z. Q.
name: Liventsev, D.
name: Miyata, H.
name: Mizuk, R.
name: Mohanty, G. B.
name: Moll, A.
name: Muramatsu, N.
name: Nakao, M.
name: Natkaniec, Z.
name: Ng, C.
name: Nishida, S.
name: Nitoh, O.
name: Ogawa, S.
name: Ohshima, T.
name: Okuno, S.
name: Olsen, S. L.
name: Onuki, Y.
name: Pakhlov, P.
name: Park, H. K.
name: Park, K. S.
name: Pedlar, T. K.
name: Pestotnik, R.
name: Petri\v, M.
name: Piilonen, L. E.
name: Röhrken, M.
name: Sakai, Y.
name: Sandilya, S.
name: Santel, D.
name: Santelj, L.
name: Sanuki, T.
name: Schneider, O.
name: Schnell, G.
name: Schwanda, C.
name: Senyo, K.
name: Shen, C. P.
name: Shibata, T. -A.
name: Shiu, J. -G.
name: Shwartz, B.
name: Simon, F.
name: Smerkol, P.
name: Sohn, Y. -S.
name: Sokolov, A.
name: Solovieva, E.
name: Stari\v, M.
name: Sumiyoshi, T.
name: Tanida, K.
name: Taniguchi, N.
name: Tatishvili, G.
name: Teramoto, Y.
name: Trabelsi, K.
name: Uehara, S.
name: Uno, S.
name: Van Hulse, C.
name: Vanhoefer, P.
name: Varner, G.
name: Wang, C. H.
name: Wang, M. -Z.
name: Wang, P.
name: Wang, X. L.
name: Watanabe, M.
name: Watanabe, Y.
name: Williams, K. M.
name: Won, E.
name: Yabsley, B. D.
name: Yamashita, Y.
name: Yuan, C. Z.
name: Zhang, Z. P.
name: Zhilich, V.
name: Zhulanov, V.
name: Zupanc, A.
Publisher: name: arXiv
Year: 2012
Subjects: subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: We study the rare hadronic transitions $Υ(2S)\rightarrow Υ(1S)η$ and $Υ(2S)\rightarrow Υ(1S)π^0$ using a sample of 158 $\times 10^6$ $Υ(2S)$ decays collected with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. We observe the $η$ meson decay to $γγ$ and $π^+π^-π^0$ final states; the $Υ(1S)$ is reconstructed in the $μ^+μ^-$ and $e^+e^-$ decay modes. We measure the ratios of branching fractions (${\mathcal B}$) $\frac{{\mathcal B}(Υ(2S)\rightarrowΥ(1S)η)}{{\mathcal B}(Υ(2S)\rightarrowΥ(1S)π^+π^-)}$ = (1.99$\pm$0.14 (stat) $\pm$0.11 (syst)) $\times 10^{-3}$ and $\frac{{\mathcal B}(Υ(2S)\rightarrowΥ(1S)π^0)}{{\mathcal B}(Υ(2S)\rightarrowΥ(1S)π^+π^-)} &lt; 2.3 \times 10^{-4}$ at the 90% confidence level (CL). Assuming the value ${\mathcal B}(Υ(2S) \rightarrow Υ(1S)π^-π^+)$ = (17.92$\pm$0.26)%, we obtain $ {\mathcal B}(Υ(2S)\rightarrowΥ(1S)η) = (3.57 \pm 0.25 ({\rm stat})\ \pm 0.21 ({\rm syst}))\times 10^{-4} $ and $ {\mathcal B}(Υ(2S)\rightarrowΥ(1S)π^0) &lt; 4.1\times 10^{-5}\ ({\rm 90%\ CL}). $
description: 6 pages, 6 figures, submitted to PRD(RC)