1201.3502 (Belle Collaboration et al.)

Measurement of the CP-violation Parameter sin2$φ_1$ with a New
Tagging Method at the $Υ(5S)$ Resonance    [PDF]

Belle Collaboration, Y. Sato, H. Yamamoto, H. Aihara, D. M. Asner, V. Aulchenko, T. Aushev, T. Aziz, A. M. Bakich, V. Bhardwaj, B. Bhuyan, M. Bischofberger, A. Bondar, A. Bozek, M. Bračko, T. E. Browder, P. Chang, P. Chen, B. G. Cheon, K. Chilikin, R. Chistov, I. -S. Cho, K. Cho, S. -K. Choi, Y. Choi, J. Dalseno, Z. Doležal, Z. Drásal, S. Eidelman, D. Epifanov, J. E. Fast, V. Gaur, N. Gabyshev, Y. M. Goh, B. Golob, J. Haba, T. Hara, K. Hayasaka, H. Hayashii, Y. Horii, Y. Hoshi, W. -S. Hou, H. J. Hyun, A. Ishikawa, R. Itoh, M. Iwabuchi, Y. Iwasaki, T. Iwashita, T. Julius, P. Kapusta, T. Kawasaki, H. Kichimi, C. Kiesling, H. J. Kim, H. O. Kim, J. B. Kim, J. H. Kim, K. T. Kim, M. J. Kim, S. K. Kim, Y. J. Kim, K. Kinoshita, B. R. Ko, N. Kobayashi, P. Kodyš, S. Korpar, P. Križan, P. Krokovny, T. Kuhr, R. Kumar, T. Kumita, A. Kuzmin, Y. -J. Kwon, J. S. Lange, S. -H. Lee, J. Li, Y. Li, C. Liu, Z. Q. Liu, R. Louvot, S. McOnie, K. Miyabayashi, H. Miyata, R. Mizuk, G. B. Mohanty, A. Moll, N. Muramatsu, E. Nakano, M. Nakao, H. Nakazawa, Z. Natkaniec, S. Nishida, K. Nishimura, O. Nitoh, S. Ogawa, T. Ohshima, S. Okuno, S. L. Olsen, Y. Onuki, W. Ostrowicz, P. Pakhlov, G. Pakhlova, C. W. Park, H. Park, H. K. Park, T. K. Pedlar, M. Petrič, L. E. Piilonen, A. Poluektov, M. Röhrken, S. Ryu, H. Sahoo, Y. Sakai, T. Sanuki, O. Schneider, C. Schwanda, A. J. Schwartz, R. Seidl, K. Senyo, O. Seon, M. E. Sevior, M. Shapkin, C. P. Shen, T. -A. Shibata, J. -G. Shiu, B. Shwartz, A. Sibidanov, F. Simon, P. Smerkol, Y. -S. Sohn, A. Sokolov, E. Solovieva, S. Stanič, M. Starič, J. Stypula, M. Sumihama, T. Sumiyoshi, S. Tanaka, G. Tatishvili, Y. Teramoto, K. Trabelsi, M. Uchida, T. Uglov, Y. Unno, S. Uno, P. Urquijo, G. Varner, K. E. Varvell, C. H. Wang, M. -Z. Wang, P. Wang, X. L. Wang, M. Watanabe, Y. Watanabe, J. Wicht, E. Won, B. D. Yabsley, Y. Yamashita, Y. Yusa, Z. P. Zhang, V. Zhilich, V. Zhulanov, A. Zupanc

We report a measurement of the CP-violation parameter sin2$\phi_1$ at the $\Upsilon(5S)$ resonance using a new tagging method, called "$B$-$\pi$ tagging." In $\Upsilon(5S)$ decays containing a neutral $B$ meson, a charged $B$, and a charged pion, the neutral $B$ is reconstructed in the $J/\psi K_S^0$ CP-eigenstate decay channel. The initial flavor of the neutral $B$ meson at the moment of the $\Upsilon(5S)$ decay is opposite to that of the charged $B$ and may thus be inferred from the charge of the pion without reconstructing the charged $B$. From the asymmetry between $B$-$\pi^+$ and $B$-$\pi^-$ tagged $J/\psi K_S^0$ yields, we determine sin2$\phi_1$ = 0.57 $\pm$ 0.58(stat) $\pm$ 0.06(syst). The results are based on 121 fb$^{-1}$ of data recorded by the Belle detector at the KEKB $e^+ e^-$ collider.

View original: http://arxiv.org/abs/1201.3502