|Vub | from B →π ν decays and (2+1)-flavor lattice QCD
|Vub | from B →π ν decays and (2+1)-flavor lattice QCD
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DOI：
10.1103/physrevd.92.014024
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发表时间：
2015-03
影响因子：
5
通讯作者：
Fermilab Lattice;M. Bailey;A. Bazavov;C. Bernard;C. Bouchard;C. DeTar;D. Du;A. El-Khadra;
中科院分区：
文献类型：
--
作者：
Fermilab Lattice;M. Bailey;A. Bazavov;C. Bernard;C. Bouchard;C. DeTar;D. Du;A. El-Khadra;
本文给出了B → πlν半轻子形状因子的格点QCD计算和CKM矩阵元的新确定|VUB|.我们使用MILC asqtad（2+1）-flavor晶格组态在四个晶格间距和轻夸克质量下降到1/20的物理奇夸克质量。我们利用交错手征微扰理论在硬介子和SU（2）极限下将晶格形状因子外推到连续谱。我们采用了一个独立于模型的z参数外推我们的晶格形状因子从大反冲动量到整个运动学范围。我们引入了一种新的泛函方法来传播从手征连续外推到z展开的信息。我们提出我们的结果连同一个完整的系统误差预算，包括协方差矩阵，使我们的形状因子与其他晶格QCD和实验结果相结合。获得|VUB|我们同时拟合了由BABAR和贝儿合作获得的B → πlν微分衰变率的实验数据以及我们的晶格形状因子结果。我们发现|VUB| =（3.72±0.16）× 10-3，其中误差来自晶格加实验的组合拟合，包括所有不确定性来源。我们的形状因子结果使QCD误差|VUB| to the same相同level水平as themore更多» experimental实验error错误.我们还提供了由格点和实验拟合得到的B → πlν矢量和标量形状因子的结果，这些结果比单独由格点QCD计算得到的结果更精确。最后，这些结果可以用于其他唯象学应用和测试QCD的其他方法。«少
We present a lattice-QCD calculation of the B → πlν semileptonic form factors and a new determination of the CKM matrix element |Vub|. We use the MILC asqtad (2+1)-flavor lattice configurations at four lattice spacings and light-quark masses down to 1/20 of the physical strange-quark mass. We extrapolate the lattice form factors to the continuum using staggered chiral perturbation theory in the hard-pion and SU(2) limits. We employ a model-independent z parametrization to extrapolate our lattice form factors from large-recoil momentum to the full kinematic range. We introduce a new functional method to propagate information from the chiral-continuum extrapolation to the z expansion. We present our results together with a complete systematic error budget, including a covariance matrix to enable the combination of our form factors with other lattice-QCD and experimental results. To obtain |Vub|, we simultaneously fit the experimental data for the B → πlν differential decay rate obtained by the BABAR and Belle collaborations together with our lattice form-factor results. We find |Vub|=(3.72±0.16) × 10–3, where the error is from the combined fit to lattice plus experiments and includes all sources of uncertainty. Our form-factor results bring the QCD error on |Vub| to the same level as themore » experimental error. We also provide results for the B → πlν vector and scalar form factors obtained from the combined lattice and experiment fit, which are more precisely determined than from our lattice-QCD calculation alone. Lastly, these results can be used in other phenomenological applications and to test other approaches to QCD.« less