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arXiv · 1810.01356

Measurement of the branching fraction and time-dependent $CP$ asymmetry for $B^0\to J/\psi\pi^0$ decays

Belle Collaboration·B. Pal·A. J. Schwartz·H. Aihara·S. Al Said·D. M. Asner·H. Atmacan·V. Aulchenko·T. Aushev·R. Ayad·I. Badhrees·S. Bahinipati·P. Behera·C. Beleño·B. Bhuyan·T. Bilka·J. Biswal·A. Bozek·M. Bračko·L. Cao·D. Červenkov·V. Chekelian·A. Chen·B. G. Cheon·K. Chilikin·K. Cho·Y. Choi·S. Choudhury·D. Cinabro·S. Cunliffe·N. Dash·S. Di Carlo·S. Eidelman·D. Epifanov·J. E. Fast·B. G. Fulsom·R. Garg·V. Gaur·A. Garmash·M. Gelb·A. Giri·P. Goldenzweig·B. Golob·Y. Guan·T. Hara·K. Hayasaka·H. Hayashii·T. Higuchi·W. -S. Hou·C. -L. Hsu·K. Inami·A. Ishikawa·R. Itoh·M. Iwasaki·Y. Iwasaki·W. W. Jacobs·S. Jia·D. Joffe·T. Julius·G. Karyan·D. Y. Kim·K. T. Kim·S. H. Kim·K. Kinoshita·P. Kodyš·S. Korpar·D. Kotchetkov·P. Križan·R. Kroeger·P. Krokovny·R. Kulasiri·R. Kumar·A. Kuzmin·Y. -J. Kwon·K. Lalwani·S. C. Lee·L. K. Li·Y. B. Li·L. Li Gioi·J. Libby·P. -C. Lu·M. Masuda·T. Matsuda·D. Matvienko·M. Merola·K. Miyabayashi·H. Miyata·R. Mizuk·G. B. Mohanty·T. Mori·E. Nakano·M. Nakao·K. J. Nath·Z. Natkaniec·M. Nayak·S. Nishida·S. Ogawa·H. Ono·G. Pakhlova·S. Pardi
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Abstract

We measure the branching fraction and time-dependent $CP$-violating asymmetry for $B^0\to J/\psi\pi^0$ decays using a data sample of 711 ${\rm fb^{-1}}$ collected on the $\Upsilon(4S)$ resonance by the Belle experiment running at the KEKB $e^+e^-$ collider. The branching fraction is measured to be $\mathcal{B}(B^0\to J/\psi\pi^0) = [1.62\,\pm 0.11~({\rm stat}) \pm0.07~({\rm syst})]\times 10^{-5}$, which is the most precise measurement to date. The measured $CP$ asymmetry parameters are $\mathcal{S} = -0.59\,\pm 0.19~({\rm stat}) \pm 0.03~({\rm syst})$ and $\mathcal{A} = -0.15\,\pm 0.14~({\rm stat})\,^{+0.04}_{-0.03}~({\rm syst})$. The mixing-induced $CP$ asymmetry ($\mathcal{S}$) differs from the case of no $CP$ violation by 3.0 standard deviations, and the direct $CP$ asymmetry ($\mathcal{A}$) is consistent with zero.

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Belle Collaboration, B. Pal, A. J. Schwartz, H. Aihara, S. Al Said, D. M. Asner, H. Atmacan, V. Aulchenko, T. Aushev, R. Ayad, I. Badhrees, S. Bahinipati, P. Behera, C. Beleño, B. Bhuyan, T. Bilka, J. Biswal, A. Bozek, M. Bračko, L. Cao, D. Červenkov, V. Chekelian, A. Chen, B. G. Cheon, K. Chilikin, K. Cho, Y. Choi, S. Choudhury, D. Cinabro, S. Cunliffe, N. Dash, S. Di Carlo, S. Eidelman, D. Epifanov, J. E. Fast, B. G. Fulsom, R. Garg, V. Gaur, A. Garmash, M. Gelb, A. Giri, P. Goldenzweig, B. Golob, Y. Guan, T. Hara, K. Hayasaka, H. Hayashii, T. Higuchi, W. -S. Hou, C. -L. Hsu, K. Inami, A. Ishikawa, R. Itoh, M. Iwasaki, Y. Iwasaki, W. W. Jacobs, S. Jia, D. Joffe, T. Julius, G. Karyan, D. Y. Kim, K. T. Kim, S. H. Kim, K. Kinoshita, P. Kodyš, S. Korpar, D. Kotchetkov, P. Križan, R. Kroeger, P. Krokovny, R. Kulasiri, R. Kumar, A. Kuzmin, Y. -J. Kwon, K. Lalwani, S. C. Lee, L. K. Li, Y. B. Li, L. Li Gioi, J. Libby, P. -C. Lu, M. Masuda, T. Matsuda, D. Matvienko, M. Merola, K. Miyabayashi, H. Miyata, R. Mizuk, G. B. Mohanty, T. Mori, E. Nakano, M. Nakao, K. J. Nath, Z. Natkaniec, M. Nayak, S. Nishida, S. Ogawa, H. Ono, G. Pakhlova, S. Pardi. 2018-10-02. Measurement of the branching fraction and time-dependent $CP$ asymmetry for $B^0\to J/\psi\pi^0$ decays. https://doi.org/10.1103/physrevd.98.112008

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