Measurement of the Direct CP Asymmetry in B ¯ → Xs+dγ Decays with a Lepton Tag

• Published in: Physical review letters 2015-04, Vol.114 (15)
• Main Authors: Urquijo, P., Dingfelder, J., Abdesselam, A., Adachi, I., Aihara, H., Arinstein, K., Asner, D. M., Aulchenko, V., Aushev, T., Ayad, R., Bahinipati, S., Bakich, A. M., Barberio, E., Bhardwaj, V., Bobrov, A., Browder, T. E., Cheon, B. G., Chobanova, V., Choi, Y., Cinabro, D., Dalseno, J., Drutskoy, A., Farhat, H., Fast, J. E., Ferber, T., Frost, O., Ganguly, S., Garmash, A., Gillard, R., Goh, Y. M., Golob, B., Haba, J., Hasenbusch, J., Heller, A., Horiguchi, T., Inami, K., Itoh, R., Iwasaki, Y., Jaegle, I., Julius, T., Kawasaki, T., Kiesling, C., Kim, J. B., Kim, J. H., Kim, M. J., Kim, Y. J., Kodyš, P., Korpar, S., Krokovny, P., Kronenbitter, B., Kumita, T., Kwon, Y. -J., Lee, I. S., Li, Y., Libby, J., Liventsev, D., Matvienko, D., Mizuk, R., Nanut, T., Natkaniec, Z., Ng, C., Ogawa, S., Okuno, S., Oswald, C., Pakhlov, P., Pakhlova, G., Pedlar, T. K., Pestotnik, R., Piilonen, L. E., Ribežl, E., Ritter, M., Rozanska, M., Sakai, Y., Sanuki, T., Schwanda, C., Senyo, K., Seon, O., Sevior, M. E., Shen, C. P., Shibata, T. -A., Shwartz, B., Sohn, Y. -S., Sokolov, A., Solovieva, E., Steder, M., Taniguchi, N., Tatishvili, G., Teramoto, Y., Uchida, M., Uglov, T., Usov, Y., Van Hulse, C., Varner, G., Vorobyev, V., Wang, B., Wang, C. H., Watanabe, Y., Yamaoka, J., Zhilich, V., Zhulanov, V.
• Format: Article
• Language: English
• Subjects: PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
• ISSN: 0031-9007; 1079-7114
• DOI: 10.1103/PhysRevLett.114.151601

We report the measurement of the direct CP asymmetry in the radiative B¯→ Xs+dγ decay using a data sample of (772 ± 11) × 106 BB¯ pairs collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e– collider. Here, the CP asymmetry is measured as a function of the photon energy threshold. For E$^{*}_{γ}$ ≥ 2.1 GeV, where E$^{*}_{γ}$ is the photon energy in the center-of-mass frame, we obtain ACP(B¯ → Xs+dγ) = (2.2 ± 3.9 ± 0.9)%, consistent with the standard model prediction.