Measurement of the lepton energy in the decay B-bar -> X l nu-bar and determination of the Heavy Quark Expansion Parameters

2002/09/12 by R. A. Briere, Briere, R. A.
Engineering · Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #Superconducting Materials and Applications #hep-ex

paper · pdf · doi:10.48550/arxiv.hep-ex/0209024

16 pages, 10 figures, submitted to ICHEP02, also available at http://www.lns.cornell.edu/public/CONF/2002/CONF02-10/paper-ichep02-lepton.ps

arxiv created 2002/09/12 · openalex publication_date 2002/09/12 · arxiv updated 2009/11/30 · openalex created_date 2024/04/11 · openalex updated_date 2026/07/28

Abstract

We measured two moments of the lepton momentum spectrum in B -> X l nu, where l= e or mu, for p_l > 1.5 GeV/c. From these we derive the Heavy Quark Expansion (HQE) parameters Lambda-bar(MS-bar) = 0.39 +- 0.03(stat) +- 0.06(sys) +- 0.12(th) GeV and lambda₁ = -0.25 +- 0.02(stat) +- 0.05(sys) +- 0.14(th) GeV², through order 1/M_B³ in the non-perturbative expansion and beta₀ alpha_s² in the perturbative expansion. The theoretical expression needed to extract |V_cb| from the measured semileptonic width is evaluated using these HQE parameters. Combined with the world average of the semileptonic width, we find |V_cb|=(40.8 +- 0.5(Gamma_sl) +- 0.4(lambda₁,Lambda-bar) +- 0.9(th)) 10^-3. Finally, the short range b-quark mass m_b(1S) is evaluated and found to be 4.82 +- 0.07(exp) +- 0.11(th) GeV/c².

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