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arXiv · 1510.01245

Study of $\mathbf{B^{0}\rightarrow\rho^{+}\rho^{-}}$ decays and implications for the CKM angle $\mathbf{\phi_2}$

P. Vanhoefer·J. Dalseno·C. Kiesling·A. Abdesselam·I. Adachi·H. Aihara·S. Al Said·K. Arinstein·D. M. Asner·H. Atmacan·T. Aushev·T. Aziz·V. Babu·I. Badhrees·A. M. Bakich·V. Bansal·E. Barberio·P. Behera·B. Bhuyan·J. Biswal·A. Bobrov·A. Bozek·M. Bracko·T. E. Browder·D. Cervenkov·P. Chang·V. Chekelian·A. Chen·B. G. Cheon·K. Chilikin·R. Chistov·V. Chobanova·S. -K. Choi·Y. Choi·D. Cinabro·M. Danilov·N. Dash·J. Dingfelder·Z. Dolezal·Z. Drasal·D. Dutta·S. Eidelman·H. Farhat·J. E. Fast·T. Ferber·B. G. Fulsom·V. Gaur·N. Gabyshev·A. Garmash·R. Gillard·Y. M. Goh·P. Goldenzweig·B. Golob·D. Greenwald·J. Haba·P. Hamer·T. Hara·K. Hayasaka·H. Hayashii·X. H. He·T. Horiguchi·W. -S. Hou·T. Iijima·K. Inami·A. Ishikawa·R. Itoh·Y. Iwasaki·W. W. Jacobs·I. Jaegle·D. Joffe·K. K. Joo·T. Julius·K. H. Kang·E. Kato·P. Katrenko·T. Kawasaki·D. Y. Kim·H. J. Kim·J. B. Kim·J. H. Kim·K. T. Kim·M. J. Kim·S. H. Kim·Y. J. Kim·K. Kinoshita·B. R. Ko·S. Korpar·P. Krizan·P. Krokovny·T. Kuhr·T. Kumita·A. Kuzmin·Y. -J. Kwon·I. S. Lee·L. Li·Y. Li·L. Li Gioi·J. Libby·D. Liventsev·P. Lukin
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Abstract

We present a measurement of the branching fraction and the longitudinal polarization fraction of $B^{0}\rightarrow\rho^+\rho^-$ decays, as well as the time-dependent $CP$ violating parameters in decays into longitudinally polarized $\rho^{+}\rho^{-}$ pairs with Belle's final data set of $772\times 10^6$ $B\bar{B}$ pairs, at the $\Upsilon(4S)$ resonance, collected at the asymmetric-energy $e^+ e^-$ collider KEKB. We obtain ${\cal B}(B^0 \rightarrow \rho^+ \rho^-)=(28.3\pm 1.5\;(\rm stat) \pm 1.5\;(\rm syst))\times 10^{-6}$, $f_L = 0.988\pm 0.012\;(\rm stat ) \pm0.023\;(\rm syst)$, ${\cal A}_{CP} = 0.00\pm0.10\;(\rm stat ) \pm0.06\;(\rm syst)$, ${\cal S}_{CP} = -0.13\pm0.15\;(\rm stat ) \pm0.05\;(\rm syst).$ We perform an isospin analysis to constrain the CKM angle $\phi_2$ and obtain two solutions with \begin{eqnarray} \phi_{2} = (93.7\pm10.6)^{\circ},\nonumber \end{eqnarray} being most compatible with other Standard-Model based fits to the data.

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P. Vanhoefer, J. Dalseno, C. Kiesling, A. Abdesselam, I. Adachi, H. Aihara, S. Al Said, K. Arinstein, D. M. Asner, H. Atmacan, T. Aushev, T. Aziz, V. Babu, I. Badhrees, A. M. Bakich, V. Bansal, E. Barberio, P. Behera, B. Bhuyan, J. Biswal, A. Bobrov, A. Bozek, M. Bracko, T. E. Browder, D. Cervenkov, P. Chang, V. Chekelian, A. Chen, B. G. Cheon, K. Chilikin, R. Chistov, V. Chobanova, S. -K. Choi, Y. Choi, D. Cinabro, M. Danilov, N. Dash, J. Dingfelder, Z. Dolezal, Z. Drasal, D. Dutta, S. Eidelman, H. Farhat, J. E. Fast, T. Ferber, B. G. Fulsom, V. Gaur, N. Gabyshev, A. Garmash, R. Gillard, Y. M. Goh, P. Goldenzweig, B. Golob, D. Greenwald, J. Haba, P. Hamer, T. Hara, K. Hayasaka, H. Hayashii, X. H. He, T. Horiguchi, W. -S. Hou, T. Iijima, K. Inami, A. Ishikawa, R. Itoh, Y. Iwasaki, W. W. Jacobs, I. Jaegle, D. Joffe, K. K. Joo, T. Julius, K. H. Kang, E. Kato, P. Katrenko, T. Kawasaki, D. Y. Kim, H. J. Kim, J. B. Kim, J. H. Kim, K. T. Kim, M. J. Kim, S. H. Kim, Y. J. Kim, K. Kinoshita, B. R. Ko, S. Korpar, P. Krizan, P. Krokovny, T. Kuhr, T. Kumita, A. Kuzmin, Y. -J. Kwon, I. S. Lee, L. Li, Y. Li, L. Li Gioi, J. Libby, D. Liventsev, P. Lukin. 2015-10-05. Study of $\mathbf{B^{0}\rightarrow\rho^{+}\rho^{-}}$ decays and implications for the CKM angle $\mathbf{\phi_2}$. https://doi.org/10.1103/physrevd.93.032010

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