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New methods for B meson decay constants and form factors from lattice NRQCD

机译:晶格NRQCD的B介子衰变常数和形状因子的新方法

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We determine the normalization of scalar and pseudoscalar current operators made from nonrelativistic b quarks and highly improved staggered light quarks in lattice quantum chromodynamics (QCD) through O ( α s ) and Λ QCD / m b . We use matrix elements of these operators to extract B meson decay constants and form factors, and then compare to those obtained using the standard vector and axial-vector operators. This provides a test of systematic errors in the lattice QCD determination of the B meson decay constants and form factors. We provide a new value for the B and B s meson decay constants from lattice QCD calculations on ensembles that include u , d , s , and c quarks in the sea and those that have the u / d quark mass going down to its physical value. Our results are f B = 0.196 ( 6 ) ? ? GeV , f B s = 0.236 ( 7 ) ? ? GeV , and f B s / f B = 1.207 ( 7 ) , agreeing well with earlier results using the temporal axial current. By combining with these previous results, we provide updated values of f B = 0.190 ( 4 ) ? ? GeV , f B s = 0.229 ( 5 ) ? ? GeV , and f B s / f B = 1.206 ( 5 ) .
机译:我们确定由非相对论性b夸克和高度改进的交错光夸克制成的标量和伪标量电流算子的归一化,这些夸克是通过O(αs)和ΛQCD / mb进行的。我们使用这些算子的矩阵元素提取B介子衰变常数和形状因子,然后与使用标准向量和轴向向量算子获得的算子进行比较。这提供了对B介子衰变常数和形状因数的晶格QCD确定中系统误差的测试。通过对包括u,d,s和c夸克在海中的夸克质量下降到其物理值的集合的格QCD计算,我们为B和B的介子衰变常数提供了新值。我们的结果是f B = 0.196(6)? ? GeV,f B s = 0.236(7)? ? GeV和f B s / f B = 1.207(7),与使用临时轴向电流的早期结果非常吻合。通过结合这些先前的结果,我们提供了f B = 0.190(4)? ? GeV,f B s = 0.229(5)? ? GeV和f B s / f B = 1.206(5)。

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