Measurement of lepton momentum moments in the decay B̄ → Xℓv̄ and determination of the heavy quark expansion parameters and |Vcb|
Measurement of lepton momentum moments in the decay B̄ → Xℓv̄ and determination of the heavy quark expansion parameters and |Vcb|
复制标题
测量衰变 B̄ → Xℓv̄ 中的轻子动量矩并确定重夸克膨胀参数和 |Vcb|
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发表时间：
2002
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通讯作者：
E. al.
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作者：
A. Mahmood;E. al.
我们测量 B-bar 到 X l nu 衰变中的初级轻子动量谱，在 B 静止坐标系中 p_l > 1.5 GeV/c。由此，我们计算频谱的各个矩。特别是，我们发现 R_0 = [int(E_l>1.7) (dGam/dE_sl)*dE_l] / [int(E_l>1.5) (dGam/dE_sl)*dE_l] = 0.6187 +/- 0.0014_stat +/- 0.0016_sys 并且 R_1 = [int(E_l>1.5) E_l(dGam/dE_sl)*dE_l] / [int(E_l>1.5) (dGam/dE_sl)*dE_l] = (1.7810 +/- 0.0007_stat +/- 0.0009_sys) GeV。我们使用这些矩来确定控制半轻子宽度的非微扰参数。特别是，我们提取重夸克膨胀参数 Lambda-bar = (0.39 +/- 0.03_stat +/- 0.06_sys +/- 0.12_th) GeV 和 lambda_1 = (-0.25 +/- 0.02_stat +/- 0.05_sys +/- 0.14_th) GeV^2。使用的理论约束通过非微扰展开中的 1/M_B^3 阶和微扰展开中的 beta_0*alpha__s^2 进行评估。我们使用这些参数来提取 |V_cb|根据半轻子宽度的世界平均值并找到 |V_cb| = (40.8 +/- 0.5_Gam-sl +/- 0.4_(lambda_1,Lambda-bar)-exp +/- 0.9_th) x 10^-3。此外，我们提取短程 b 夸克质量 m_b^1S = (4.82 +/- 0.07_exp +/- 0.11_th) GeV/c^2。最后，我们讨论了我们的测量对包容半轻过程的理论理解的影响。
We measure the primary lepton momentum spectrum in B-bar to X l nu decays, for p_l > 1.5 GeV/c in the B rest frame. From this, we calculate various moments of the spectrum. In particular, we find R_0 = [int(E_l>1.7) (dGam/dE_sl)*dE_l] / [int(E_l>1.5) (dGam/dE_sl)*dE_l] = 0.6187 +/- 0.0014_stat +/- 0.0016_sys and R_1 = [int(E_l>1.5) E_l(dGam/dE_sl)*dE_l] / [int(E_l>1.5) (dGam/dE_sl)*dE_l] = (1.7810 +/- 0.0007_stat +/- 0.0009_sys) GeV. We use these moments to determine non-perturbative parameters governing the semileptonic width. In particular, we extract the Heavy Quark Expansion parameters Lambda-bar = (0.39 +/- 0.03_stat +/- 0.06_sys +/- 0.12_th) GeV and lambda_1 = (-0.25 +/- 0.02_stat +/- 0.05_sys +/- 0.14_th) GeV^2. The theoretical constraints used are evaluated through order 1/M_B^3 in the non-perturbative expansion and beta_0*alpha__s^2 in the perturbative expansion. We use these parameters to extract |V_cb| from the world average of the semileptonic width and find |V_cb| = (40.8 +/- 0.5_Gam-sl +/- 0.4_(lambda_1,Lambda-bar)-exp +/- 0.9_th) x 10^-3. In addition, we extract the short range b-quark mass m_b^1S = (4.82 +/- 0.07_exp +/- 0.11_th) GeV/c^2. Finally, we discuss the implications of our measurements for the theoretical understanding of inclusive semileptonic processes.