Measurement of the Direct CP Asymmetry in B¯→X(s+dγ) Decays with a Lepton Tag

• Published in: Physical review letters 2015-04, Vol.114 (15), p.151601-151601
• Main Authors: Pesántez, L, Urquijo, P, Dingfelder, J, Abdesselam, A, Adachi, I, Adamczyk, K, Aihara, H, Al Said, S, Arinstein, K, Asner, D M, Aulchenko, V, Aushev, T, Ayad, R, Bahinipati, S, Bakich, A M, Bansal, V, Barberio, E, Bhardwaj, V, Bhuyan, B, Bobrov, A, Bondar, A, Bonvicini, G, Bozek, A, Bračko, M, Browder, T E, Červenkov, D, Chekelian, V, Chen, A, Cheon, B G, Chilikin, K, Chistov, R, Cho, K, Chobanova, V, Choi, Y, Cinabro, D, Dalseno, J, Doležal, Z, Drásal, Z, Drutskoy, A, Dutta, D, Eidelman, S, Farhat, H, Fast, J E, Ferber, T, Frost, O, Gaur, V, Gabyshev, N, Ganguly, S, Garmash, A, Getzkow, D, Gillard, R, Goh, Y M, Golob, B, Haba, J, Hasenbusch, J, Hayashii, H, He, X H, Heller, A, Horiguchi, T, Hou, W-S, Huschle, M, Iijima, T, Inami, K, Ishikawa, A, Itoh, R, Iwasaki, Y, Jaegle, I, Joffe, D, Julius, T, Kang, K H, Kato, E, Kawasaki, T, Kiesling, C, Kim, D Y, Kim, J B, Kim, J H, Kim, K T, Kim, M J, Kim, S H, Kim, Y J, Ko, B R, Kodyš, P, Korpar, S, Križan, P, Krokovny, P, Kronenbitter, B, Kuhr, T, Kumita, T, Kuzmin, A, Kwon, Y-J, Lange, J S, Lee, I S, Li, Y, Li Gioi, L, Libby, J, Liventsev, D, Lukin, P, Matvienko, D, Miyabayashi, K, Miyata, H
• Format: Article
• Language: English
• ISSN: 1079-7114

We report the measurement of the direct CP asymmetry in the radiative B¯→X(s+dγ) decay using a data sample of (772 ± 11)×10(6) BB[over ¯] pairs collected at the ϒ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. The CP asymmetry is measured as a function of the photon energy threshold. For Eγ*≥2.1  GeV, where Eγ* is the photon energy in the center-of-mass frame, we obtain A(CP)(B¯→X(s+dγ))=(2.2±3.9±0.9)%, consistent with the standard model prediction.