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ISSN - 03702693, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 2005, vol. 621, p. 28-40

Measurement of |Vub| near the endpoint of the electron momentum spectrum from semileptonic B-meson decays

Limosani A., Abe K., Abe K., Adachi I., Aihara H., Asano Y., Aushev T., Bahinipati S., Bakich A. M., Barberio E., Bitenc U., Bizjak I., Blyth S., Bondar A., Bozek A., Bračko M., Brodzicka J., Browder T. E., Chao Y., Chen A., Chen K. F., Chen W. T., Cheon B. G., Chistov R., Choi Y., Chuvikov A., Cole S., Dalseno J., Danilov M., Dash M., Dragic J., Drutskoy A., Eidelman S., Fratina S., Gabyshev N., Gershon T., Gokhroo G., Golob B., Gorišek A., Hara T., Hastings N. C., Hayasaka K., Hayashii H., Hazumi M., Hinz L., Hokuue T., Hoshi Y., Hou S., Hou W. S., Iijima T., Imoto A., Inami K., Ishikawa A., Itoh R., Iwasaki M., Iwasaki Y., Kang J. H., Kang J. S., Katayama N., Kawai H., Kawasaki T., Khan H. R., Kichimi H., Kim H. J., Kim H. O., Kim S. K., Kim S. M., Kinoshita K., Korpar S., Krokovny P., Kulasiri R., Kumar S., Kuo C. C., Kwon Y. J., Lange J. S., Leder G., Lesiak T., Li J., Lin S. W., Liventsev D., MacNaughton J., Majumder G., Mandl F., Matsumoto T., Mikami Y., Mitaroff W., Miyabayashi K., Miyake H., Miyata H., Mizuk R., Mohapatra D., Mori T., Nagamine T., Nagasaka Y., Nakano E., Nakao M.

We report measurements of partial branching fractions of inclusive charmless semileptonic B-meson decays at the endpoint of the electron momentum spectrum. The measurements are made in six overlapping momentum intervals that have lower bounds ranging from 1.9 to 2.4 GeV/c and a common upper bound of 2.6 GeV/c, as measured in the centre of mass frame. The results are based on a sample of 29 million BB̄ pairs, accumulated by the Belle detector at the KEKB asymmetric e+e- collider operating on the Υ(4S) resonance. In the momentum interval ranging from 1.9 to 2.6 GeV/c we measure the partial branching fraction ΔB(B→Xueνe)=(8.47±0.37±1.53)×10-4, where the first error is statistical and the second is systematic. A prediction of the partial rate R=(21.69±3.62-1.98+2.18)|Vub|2 ps-1 in this momentum interval based on theory is calculated with input HQET parameters that have been derived from Belle's measurement of the B→Xsγ photon energy spectrum, where the first error is due to the uncertainty on HQET parameters and the second error is from theory. Using both ΔB(B→Xueνe) and R we find |V ub|=(5.08±0.47±0.42-0.23+0.26)×10-3, where the first error is from the partial branching fraction, and the second and third errors are from uncertainties in R. © 2005 Elsevier B.V. All rights reserved.