Measurement of the branching fraction and $CP$ asymmetry in $B^{0} \to π^{0}π^{0}$ decays, and an improved constraint on $ϕ_{2}$
Creators: name: The Belle Collaboration
name: Julius, T.
name: Sevior, M. E.
name: Mohanty, G. B.
name: Adachi, I.
name: Aihara, H.
name: Said, S. Al
name: Asner, D. M.
name: Aulchenko, V.
name: Aushev, T.
name: Ayad, R.
name: Babu, V.
name: Badhrees, I.
name: Bakich, A. M.
name: Bansal, V.
name: Barberio, E.
name: Barrett, M.
name: Berger, M.
name: Bhardwaj, V.
name: Bhuyan, B.
name: Biswal, J.
name: Bloomfield, T.
name: Bobrov, A.
name: Bondar, A.
name: Bonvicini, G.
name: Bozek, A.
name: Bračko, M.
name: Browder, T. E.
name: Červenkov, D.
name: Chang, M. -C.
name: Chao, Y.
name: Chekelian, V.
name: Chen, A.
name: Cheon, B. G.
name: Chilikin, K.
name: Cho, K.
name: Choi, Y.
name: Cinabro, D.
name: Dash, N.
name: Di Carlo, S.
name: Doležal, Z.
name: Dossett, D.
name: Drásal, Z.
name: Dutta, D.
name: Eidelman, S.
name: Farhat, H.
name: Fast, J. E.
name: Ferber, T.
name: Fulsom, B. G.
name: Gaur, V.
name: Gabyshev, N.
name: Garmash, A.
name: Gillard, R.
name: Goldenzweig, P.
name: Haba, J.
name: Hara, T.
name: Hayasaka, K.
name: Hayashii, H.
name: Hou, W. -S.
name: Hsu, C. -L.
name: Iijima, T.
name: Inami, K.
name: Ishikawa, A.
name: Itoh, R.
name: Iwasaki, Y.
name: Jacobs, W. W.
name: Jaegle, I.
name: Jin, Y.
name: Joffe, D.
name: Joo, K. K.
name: Kahn, J.
name: Karyan, G.
name: Katrenko, P.
name: Kawasaki, T.
name: Kiesling, C.
name: Kim, D. Y.
name: Kim, H. J.
name: Kim, J. B.
name: Kim, K. T.
name: Kim, M. J.
name: Kim, S. H.
name: Kim, Y. J.
name: Kinoshita, K.
name: Kodyš, P.
name: Korpar, S.
name: Kotchetkov, D.
name: Križan, P.
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: Li, C. H.
name: Li, L.
name: Li, Y.
name: Gioi, L. Li
name: Libby, J.
name: Liventsev, D.
name: Luo, T.
name: MacNaughton, J.
name: Masuda, M.
name: Matsuda, T.
name: Merola, M.
name: Miyabayashi, K.
name: Miyata, H.
name: Mizuk, R.
name: Moon, H. K.
name: Mori, T.
name: Mussa, R.
name: Nakano, E.
name: Nakao, M.
name: Nanut, T.
name: Nath, K. J.
name: Natkaniec, Z.
name: Nayak, M.
name: Nisar, N. K.
name: Nishida, S.
name: Ogawa, S.
name: Ono, H.
name: Pakhlov, P.
name: Pakhlova, G.
name: Pal, B.
name: Pardi, S.
name: Park, C. -S.
name: Park, H.
name: Pesántez, L.
name: Pestotnik, R.
name: Piilonen, L. E.
name: Pulvermacher, C.
name: Ritter, M.
name: Sahoo, H.
name: Sakai, Y.
name: Salehi, M.
name: Sandilya, S.
name: Santelj, L.
name: Sanuki, T.
name: Sato, Y.
name: Savinov, V.
name: Schneider, O.
name: Schnell, G.
name: Schwanda, C.
name: Schwartz, A. J.
name: Seino, Y.
name: Senyo, K.
name: Shebalin, V.
name: Shibata, T. -A.
name: Shiu, J. -G.
name: Shwartz, B.
name: Sokolov, A.
name: Solovieva, E.
name: Starič, M.
name: Sumiyoshi, T.
name: Tamponi, U.
name: Tanida, K.
name: Tenchini, F.
name: Trabelsi, K.
name: Uchida, M.
name: Uehara, S.
name: Uglov, T.
name: Unno, Y.
name: Uno, S.
name: Urquijo, P.
name: Usov, Y.
name: Van Hulse, C.
name: Varner, G.
name: Varvell, K. E.
name: Vossen, A.
name: Waheed, E.
name: Wang, C. H.
name: Wang, M. -Z.
name: Wang, P.
name: Watanabe, M.
name: Watanabe, Y.
name: Widmann, E.
name: Williams, K. M.
name: Won, E.
name: Yamashita, Y.
name: Ye, H.
name: Yuan, C. Z.
name: Yusa, Y.
name: Zhang, Z. P.
name: Zhilich, V.
name: Zhulanov, V.
name: Zupanc, A.
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: We measure the branching fraction and $CP$ violation asymmetry in the decay $B^{0}\to π^{0}π^{0}$, using a data sample of $752\times 10^{6}$ $B\bar{B}$ pairs collected at the $Υ(4S)$ resonance with the Belle detector at the KEKB $e^{+}e^{-}$ collider. The obtained branching fraction and direct $CP$ asymmetry are $ \mathcal{B}(B\to π^{0}π^{0}) = [1.31 \pm 0.19~ \text{(stat.)} \pm 0.19~ \text{(syst.)}] \times 10^{-6}$ and $ A_{CP} = +0.14 \pm 0.36~ \text{(stat.)} \pm 0.10~ \text{(syst.)}, $ respectively. The signal significance, including the systematic uncertainty, is 6.4 standard deviations. We combine these results with Belle's earlier measurements of $B^{0}\to π^{+} π^{-}$ and $B^{\pm} \to π^{\pm} π^{0}$ to exclude the $CP$-violating parameter $ϕ_{2}$ from the range $15.5^{\circ} &lt; ϕ_{2} &lt; 75.0^{\circ}$ at 95\% confidence level.
description: 8 pages, 2 figures