Measurement of lepton momentum moments in the decay B̄ → Xℓv̄ and determination of the heavy quark expansion parameters and |Vcb|

A. H. Mahmood, S. E. Csorna, I. Danko, G. Bonvicini, D. Cinabro, M. Dubrovin, S. McGee, A. Bornheim, E. Lipeles, S. P. Pappas, A. Shapiro, W. M. Sun, A. J. Weinstein, R. A. Briere, G. P. Chen, T. Ferguson, G. Tatishvili, H. Vogel, N. E. Adam, J. P. AlexanderK. Berkelman, V. Boisvert, D. G. Cassel, P. S. Drell, J. E. Duboscq, K. M. Ecklund, R. Ehrlich, R. S. Galik, L. Gibbons, B. Gittelman, S. W. Gray, D. L. Hartill, B. K. Heltsley, L. Hsu, C. D. Jones, J. Kandaswamy, D. L. Kreinick, A. Magerkurth, H. Mahlke-Krüger, T. O. Meyer, N. B. Mistry, J. R. Patterson, D. Peterson, J. Pivarski, S. J. Richichi, D. Riley, A. J. Sadoff, H. Schwarthoff, M. R. Shepherd, J. G. Thayer

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24 Scopus citations

Abstract

We measure the primary lepton momentum spectrum in B̄→Xℓ v̄ decays, for p≥ 1.5 GeV/c in the B rest frame. From this, we calculate various moments of the spectrum. In particular, we find R0 ≡ ∫1.7 GeV(dΓ/dE sl)dE/∫1.5 GeV(dΓ/ dEsl)dE=0.6187±0.0014stat±0. 0016sys and R11.5 GeVE (dΓ/dEsl)dE/∫ 1.5 GeV(dΓ/dEsl)dE=(1. 7810±0.0007stat±0.0009sys) GeV. We use these moments to determine non-perturbative parameters governing the semileptonic width. In particular, we extract the heavy quark expansion parameters Λ̄=(0.39±0.03stat±0.06 sys±0.12th) GeV and λ1 = (-0.25±0.02stat±0.05sys ±0.14 th) GeV2. The theoretical constraints used are evaluated through order 1/MB 3 in the non-perturbative expansion and β0αs 2 in the perturbative expansion. We use these parameters to extract |Vcb| from the world average of the semileptonic width and find |Vcb| = (40.8±0.5 Γsl±0.4 (λ1,Λ̄)exp±0.9th)× 10 -3. In addition, we extract the short range b-quark mass m b 1S=(4.82±0.070exp±0.11 th) GeV/c2. Finally, we discuss the implications of our measurements for the theoretical understanding of inclusive semileptonic processes.

Original languageEnglish (US)
Article number072001
JournalPhysical Review D
Volume67
Issue number7
DOIs
StatePublished - Apr 23 2003

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