Measurements of isospin asymmetry and difference of direct CP asymmetries in inclusive B→Xsγ decays

Watanuki, S.; Ishikawa, A.; Adachi, I.; Aihara, H.; Al Said, S.; Asner, D.  M.; Aushev, T.; Ayad, R.; Babu, V.; Badhrees, I.; Bakich, A.  M.; Bansal, V.; Behera, P.; Beleño, C.; Berger, M.; Bhardwaj, V.; Bhuyan, B.; Bilka, T.; Biswal, J.; Bobrov, A.; Bonvicini, G.; Bozek, A.; Bračko, M.; Browder, T.  E.; Cao, L.; Červenkov, D.; Chang, P.; Cheon, B.  G.; Chilikin, K.; Cho, K.; Choi, Y.; Choudhury, S.; Cinabro, D.; Cunliffe, S.; Di Carlo, S.; Dingfelder, J.; Dong, T.  V.; Eidelman, S.; Epifanov, D.; Fast, J.  E.; Ferber, T.; Frey, A.; Fulsom, B.  G.; Gaur, V.; Gabyshev, N.; Garmash, A.; Gelb, M.; Giri, A.; Goldenzweig, P.; Guan, Y.; Guido, E.; Haba, J.; Hayasaka, K.; Hayashii, H.; Hou, W. -S.; Iijima, T.; Inami, K.; Inguglia, G.; Itoh, R.; Iwasaki, M.; Iwasaki, Y.; Jacobs, W.  W.; Jaegle, I.; Jeon, H.  B.; Jia, S.; Jin, Y.; Joo, K.  K.; Julius, T.; Karyan, G.; Kawasaki, T.; Kiesling, C.; Kim, D.  Y.; Kim, J.  B.; Kim, S.  H.; Kinoshita, K.; Kodyš, P.; Korpar, S.; Kotchetkov, D.; Križan, P.; Kroeger, R.; Krokovny, P.; Kuhr, T.; Kumar, R.; Kuzmin, A.; Kwon, Y. -J.; Lee, I.  S.; Lee, S.  C.; L.  K., Li; Y.  B., Li; Li Gioi, L.; Libby, J.; Liventsev, D.; Lubej, M.; Luo, T.; Masuda, M.; Matsuda, T.; Merola, M.; Miyabayashi, K.; Miyata, H.; Mizuk, R.; Mohanty, G.  B.; Mori, T.; Nakao, M.; Nanut, T.; Nath, K.  J.; Niiyama, M.; Nishida, S.; Nishimura, K.; Ogawa, K.; Ogawa, S.; Okuno, S.; Ono, H.; Ostrowicz, W.; Pakhlov, P.; Pakhlova, G.; Pal, B.; Park, H.; Paul, S.; Pedlar, T.  K.; Pestotnik, R.; Piilonen, L.  E.; Prencipe, E.; Ritter, M.; Rostomyan, A.; Russo, G.; Sakai, Y.; Sandilya, S.; Santelj, L.; Savinov, V.; Schneider, O.; Schnell, G.; Schueler, J.; Schwanda, C.; Schwartz, A.  J.; Seino, Y.; Senyo, K.; Seon, O.; Shebalin, V.; Shibata, T. -A.; Shiu, J. -G.; Shwartz, B.; Sokolov, A.; Solovieva, E.; Stanič, S.; Starič, M.; Sumiyoshi, T.; Sutcliffe, W.; Takizawa, M.; Tanida, K.; Taniguchi, N.; Tenchini, F.; Uchida, M.; Uglov, T.; Unno, Y.; Uno, S.; Vahsen, S.  E.; Van Hulse, C.; Van Tonder, R.; Varner, G.; Varvell, K.  E.; Vossen, A.; Wang, B.; Wang, C.  H.; Wang, M. -Z.; Wang, P.; Watanabe, M.; Widmann, E.; Won, E.; Ye, H.; Yin, J.  H.; Yusa, Y.; Zakharov, S.; Zhang, Z.  P.; Zhilich, V.; Zhukova, V.; Zhulanov, V.; Zupanc, A.; Null, Null

doi:10.1103/physrevd.99.032012

We report measurements of isospin asymmetry Delta(0-) and difference of direct CP asymmetries Delta A(CP) between charged and neutral B -> Xs gamma decays. This analysis is based on the data sample containing 772 x 10^6 BB-bar pairs that was collected with the Belle detector at the KEKB energy-asymmetric e+e- collider. Using a sum-of-exclusive technique with invariant Xs mass up to 2.8 GeV= c2, we obtain Delta(0-) = [0.48 +/- 1.49(stat) +/- 0.97(syst) +/- 1.15(f(+-)/f(00))]% and Delta A(CP) = [+3.69 +/- 2.65(stat) +/- 0.76(syst)]%, where the last uncertainty for Delta(0-) is due to the uncertainty on the production ratio of B+B- to B0B0-bar in Y(4S) decays. The measured value of Delta(0-) is consistent with zero, allowing us to constrain the resolved photon contribution in the B -> Xs 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 -> Xs gamma decays. All the measurements are the most precise to date.