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arXiv · 1810.03336

Measurement of time-dependent $CP$ violation in $B^0 \to K^0_S \pi^0 \pi^0$ decays

Belle Collaboration·Y. Yusa·H. Aihara·S. Al Said·D. M. Asner·H. Atmacan·V. Aulchenko·T. Aushev·R. Ayad·V. Babu·I. Badhrees·S. Bahinipati·A. M. Bakich·V. Bansal·P. Behera·V. Bhardwaj·B. Bhuyan·J. Biswal·A. Bozek·M. Bračko·T. E. Browder·L. Cao·D. Červenkov·V. Chekelian·A. Chen·B. G. Cheon·K. Chilikin·S. -K. Choi·Y. Choi·D. Cinabro·S. Cunliffe·N. Dash·S. Di Carlo·T. V. Dong·Z. Drásal·S. Eidelman·D. Epifanov·J. E. Fast·B. G. Fulsom·R. Garg·V. Gaur·A. Giri·P. Goldenzweig·B. Golob·Y. Guan·J. Haba·K. Hayasaka·H. Hayashii·S. Hirose·K. Inami·G. Inguglia·A. Ishikawa·M. Iwasaki·Y. Iwasaki·W. W. Jacobs·S. Jia·Y. Jin·K. K. Joo·K. H. Kang·T. Kawasaki·D. Y. Kim·J. B. Kim·K. T. Kim·S. H. Kim·K. Kinoshita·P. Kodyš·S. Korpar·D. Kotchetkov·P. Križan·R. Kroeger·T. Kuhr·R. Kumar·Y. -J. Kwon·J. S. Lange·I. S. Lee·S. C. Lee·L. K. Li·Y. B. Li·L. Li Gioi·J. Libby·D. Liventsev·M. Lubej·T. Luo·M. Masuda·T. Matsuda·M. Merola·K. Miyabayashi·H. Miyata·R. Mizuk·G. B. Mohanty·H. K. Moon·E. Nakano·T. Nanut·K. J. Nath·Z. Natkaniec·N. K. Nisar·S. Nishida·K. Nishimura·K. Ogawa·S. Ogawa
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Abstract

We report a measurement of time-dependent $CP$ violation in $B^0 \to K^0_S \pi^0 \pi^0$ decays using a data sample of $772 \times 10^6$ $B\bar{B}$ pairs collected by the Belle experiment runnin g at the $\Upsilon (4S)$ resonance at the KEKB $e^+ e^-$ collider. This decay proceeds mainly via a $b\to sd\bar{d}$ "penguin" amplitude. The results are $\sin 2\phi^{\rm eff}_1 = 0.92^{+0.27}_{-0.31}~$ (stat.) $\pm 0.11$ (syst.) and $\mathcal{A} = 0.28 \pm 0.21$ (stat.) $\pm 0.04$ (syst.), which are the most precise measurements of $CP$ violati on in this decay mode to date. The value for the $CP$-violating parameter $\sin 2\phi^{\rm eff}_1$ is consistent with that obtained using decay modes proceeding via a $b\to c\bar{c}s$ "tree" amplitude.

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Belle Collaboration, Y. Yusa, H. Aihara, S. Al Said, D. M. Asner, H. Atmacan, V. Aulchenko, T. Aushev, R. Ayad, V. Babu, I. Badhrees, S. Bahinipati, A. M. Bakich, V. Bansal, P. Behera, V. Bhardwaj, B. Bhuyan, J. Biswal, A. Bozek, M. Bračko, T. E. Browder, L. Cao, D. Červenkov, V. Chekelian, A. Chen, B. G. Cheon, K. Chilikin, S. -K. Choi, Y. Choi, D. Cinabro, S. Cunliffe, N. Dash, S. Di Carlo, T. V. Dong, Z. Drásal, S. Eidelman, D. Epifanov, J. E. Fast, B. G. Fulsom, R. Garg, V. Gaur, A. Giri, P. Goldenzweig, B. Golob, Y. Guan, J. Haba, K. Hayasaka, H. Hayashii, S. Hirose, K. Inami, G. Inguglia, A. Ishikawa, M. Iwasaki, Y. Iwasaki, W. W. Jacobs, S. Jia, Y. Jin, K. K. Joo, K. H. Kang, T. Kawasaki, D. Y. Kim, J. B. Kim, K. T. Kim, S. H. Kim, K. Kinoshita, P. Kodyš, S. Korpar, D. Kotchetkov, P. Križan, R. Kroeger, T. Kuhr, R. Kumar, Y. -J. Kwon, J. S. Lange, I. S. Lee, S. C. Lee, L. K. Li, Y. B. Li, L. Li Gioi, J. Libby, D. Liventsev, M. Lubej, T. Luo, M. Masuda, T. Matsuda, M. Merola, K. Miyabayashi, H. Miyata, R. Mizuk, G. B. Mohanty, H. K. Moon, E. Nakano, T. Nanut, K. J. Nath, Z. Natkaniec, N. K. Nisar, S. Nishida, K. Nishimura, K. Ogawa, S. Ogawa. 2018-10-08. Measurement of time-dependent $CP$ violation in $B^0 \to K^0_S \pi^0 \pi^0$ decays. https://doi.org/10.1103/physrevd.99.011102

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