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ISSN - 15507998, Physical Review D - Particles, Fields, Gravitation and Cosmology, 2015, vol. 91, 1, p. -

Search for B s 0 → γ γ and a measurement of the branching fraction for B s 0 → φ γ

Dutta D., Bhuyan B., Abdesselam A., Adachi I., Aihara H., Al Said S., Arinstein K., Asner D. M., Aulchenko V., Aushev T., Ayad R., Aziz T., Bahinipati S., Bakich A. M., Bansal V., Bhardwaj V., Bobrov A., Bonvicini G., Bračko M., Browder T. E., Červenkov D., 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 K., Eidelman S., Farhat H., Fast J. E., Frost O., Gaur V., Ganguly S., Garmash A., Getzkow D., Goh Y. M., Golob B., Hayashii H., He X. H., Hou W. S., Iijima T., Ishikawa A., Iwasaki Y., Jaegle I., Joffe D., Kang K. H., Kato E., Kiesling C., Kim D. Y., Kim J. B., Kim J. H., Kim K. T., Kim M. J., Kim S. H., Kim Y. J., Kinoshita K., Ko B. R., Kodyš P., Korpar S., KriŽan P., Krokovny P., Kuhr T., Kuzmin A., Kwon Y. J., Lange J. S., Lee I. S., Lewis P., Li Y., Li Gioi L., Libby J., Liventsev D., Matvienko D., Miyata H., Mizuk R., Mohanty G. B., Moll A., Mori T., Mussa R., Nakano E., Nakao M.

© 2015 American Physical Society. We search for the decay Bs0→γγ and measure the branching fraction for Bs0→φγ using 121.4 fb-1 of data collected at the (5S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. The Bs0→φγ branching fraction is measured to be (3.6±0.5(stat)±0.3(syst)±0.6(fs))×10-5, where fs is the fraction of Bs(∗)B¯s(∗) in bb¯ events. Our result is in good agreement with the theoretical predictions as well as with a recent measurement from LHCb. We observe no statistically significant signal for the decay Bs0→γγ and set a 90% confidence-level upper limit on its branching fraction at 3.1×10-6. This constitutes a significant improvement over the previous result.