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arXiv · 1807.04236

Measurements of isospin asymmetry and difference of direct $CP$ asymmetries in inclusive $B \to X_s \gamma$ decays

S. Watanuki·A. Ishikawa·I. Adachi·H. Aihara·S. Al Said·D. M. Asner·T. Aushev·R. Ayad·V. Babu·I. Badhrees·A. M. Bakich·V. Bansal·P. Behera·C. Belen·M. Berger·V. Bhardwaj·B. Bhuyan·T. Bilka·J. Biswal·A. Bobrov·G. Bonvicini·A. Bozek·M. Brač·T. E. Browder·L. Cao·D. C·P. Chang·B. G. Cheon·K. Chilikin·K. Cho·Y. Choi·S. Choudhury·D. Cinabro·S. Cunliffe·S. Di Carlo·J. Dingfelder·T. V. Dong·S. Eidelman·D. Epifanov·J. E. Fast·T. Ferber·A. Frey·B. G. Fulsom·V. Gaur·N. Gabyshev·A. Garmash·M. Gelb·A. Giri·P. Goldenzweig·Y. Guan·E. Guido·J. Haba·K. Hayasaka·H. Hayashii·W. -S. Hou·T. Iijima·K. Inami·G. Inguglia·R. Itoh·M. Iwasaki·Y. Iwasaki·W. W. Jacobs·I. Jaegle·H. B. Jeon·S. Jia·Y. Jin·K. K. Joo·T. Julius·G. Karyan·T. Kawasaki·C. Kiesling·D. Y. Kim·J. B. Kim·S. H. Kim·K. Kinoshita·P. Kodyš·S. Korpar·D. Kotchetkov·P. Križ·R. Kroeger·P. Krokovny·T. Kuhr·R. Kumar·A. Kuzmin·Y. -J. Kwon·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
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Abstract

We report measurements of isospin asymmetry $\Delta_{0-}$ and difference of direct $CP$ asymmetries $\Delta A_{CP}$ between charged and neutral $B \to X_s \gamma$ decays. This analysis is based on the data sample containing $772 \times 10^6 B\bar{B}$ pairs that was collected with the Belle detector at the KEKB energy-asymmetric $e^+ e^-$ collider. Using a sum-of-exclusive technique with invariant $X_s$ mass up to 2.8~GeV/$c^2$, we obtain $\Delta_{0-} = \bigl[-0.48 \pm 1.49 {\rm (stat.)} \pm 0.97 {\rm (syst.)} \pm 1.15 {(f_{+-}/f_{00})}\bigr]$\% and $\Delta A_{CP} = \bigl[+3.69 \pm 2.65 {\rm (stat.)} \pm 0.76{\rm (syst.)}\bigr]$\%, where the last uncertainty for $\Delta_{0-}$ is due to the uncertainty on the production ratio of $B^+B^-$ to $B^0\bar{B}^0$ in $\Upsilon(4S)$ decays. The measured value of $\Delta_{0-}$ is consistent with zero, allowing us to constrain the resolved photon contribution in the $B \to X_s \gamma$, and improve the branching fraction prediction. The result for $\Delta A_{CP}$ is consistent with the prediction of the SM. We also measure the direct $CP$ asymmetries for charged and neutral $B \to X_s \gamma$ decays. All the measurements are the most precise to date.

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S. Watanuki, A. Ishikawa, I. Adachi, H. Aihara, S. Al Said, D. M. Asner, T. Aushev, R. Ayad, V. Babu, I. Badhrees, A. M. Bakich, V. Bansal, P. Behera, C. Belen, M. Berger, V. Bhardwaj, B. Bhuyan, T. Bilka, J. Biswal, A. Bobrov, G. Bonvicini, A. Bozek, M. Brač, T. E. Browder, L. Cao, D. C, P. Chang, B. G. Cheon, K. Chilikin, K. Cho, Y. Choi, S. Choudhury, D. Cinabro, S. Cunliffe, S. Di Carlo, J. Dingfelder, T. V. Dong, S. Eidelman, D. Epifanov, J. E. Fast, T. Ferber, A. Frey, B. G. Fulsom, V. Gaur, N. Gabyshev, A. Garmash, M. Gelb, A. Giri, P. Goldenzweig, Y. Guan, E. Guido, J. Haba, K. Hayasaka, H. Hayashii, W. -S. Hou, T. Iijima, K. Inami, G. Inguglia, R. Itoh, M. Iwasaki, Y. Iwasaki, W. W. Jacobs, I. Jaegle, H. B. Jeon, S. Jia, Y. Jin, K. K. Joo, T. Julius, G. Karyan, T. Kawasaki, C. Kiesling, D. Y. Kim, J. B. Kim, S. H. Kim, K. Kinoshita, P. Kodyš, S. Korpar, D. Kotchetkov, P. Križ, R. Kroeger, P. Krokovny, T. Kuhr, R. Kumar, A. Kuzmin, Y. -J. Kwon, 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. 2018-07-11. Measurements of isospin asymmetry and difference of direct $CP$ asymmetries in inclusive $B \to X_s \gamma$ decays. https://doi.org/10.1103/physrevd.99.032012

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