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ISSN - 15507998, Physical Review D - Particles, Fields, Gravitation and Cosmology, 2016, vol. 93, 3, p. -

Measurement of the lepton forward-backward asymmetry in B →xs+-decays with a sum of exclusive modes

Sato Y., Ishikawa A., Yamamoto H., Abdesselam A., Adachi I., Adamczyk K., Aihara H., Asner D. M., Aulchenko V., Aushev T., Ayad R., Bakich A. M., Bala A., Bhardwaj V., Bhuyan B., Bondar A., Bonvicini G., Bozek A., Bračko M., Browder T. E., Červenkov D., Chekelian V., Chen A., Cheon B. G., Cho I. S., Cho K., Chobanova V., Choi Y., Cinabro D., Dalseno J., Danilov M., DoleŽal Z., Drásal Z., Drutskoy A., Dutta D., Dutta K., Eidelman S., Farhat H., Fast J. E., Ferber T., Gaur V., Garmash A., Gillard R., Goh Y. M., Golob B., Haba J., Hara T., Hayasaka K., Hayashii H., He X. H., Hoshi Y., Hou W. S., Hyun H. J., Iijima T., Itoh R., Iwasaki Y., Iwashita T., Jaegle I., Julius T., Kang J. H., Kato E., Kato Y., Kawai H., Kawasaki T., Kichimi H., Kim D. Y., Kim H. J., Kim J. B., Kim J. H., Kim M. J., Kim Y. J., Kinoshita K., Klucar J., Ko B. R., Kodyš P., Korpar S., KriŽan P., Krokovny P., Kuhr T., Kumita T., Kuzmin A., Kwon Y. J., Lee S. H., Li Y., Libby J., Liu C., Liu Y., Liu Z. Q., Liventsev D., Lukin P., Miyata H., Mizuk R.

© 2016 American Physical Society.We report the first measurement of the lepton forward-backward asymmetry AFB as a function of the squared four-momentum of the dilepton system, q2, for the electroweak penguin process B→Xs+- with a sum of exclusive final states, where is an electron or a muon and Xs is a hadronic recoil system with an s quark. The results are based on a data sample containing 772×106 BB¯ pairs recorded at the (4S) resonance with the Belle detector at the KEKB e+e- collider. AFB for the inclusive B→Xs+- is extrapolated from the sum of 10 exclusive Xs states whose invariant mass is less than 2 GeV/c2. For q2>10.2 GeV2/c2, AFB<0 is excluded at the 2.3σ level, where σ is the standard deviation. For q2<4.3 GeV2/c2, the result is within 1.8σ of the standard model theoretical expectation.