论文标题
$ b_c \ to b_ {s（d）} $ from from lattice qcd
$B_c \to B_{s(d)}$ form factors from lattice QCD
论文作者
论文摘要
我们将$ b_c \ $ b_c \的第一个晶格QCD计算结果介绍给b_s $和$ b_c \ to b_d $弱矩阵元素。然后，在与CKM矩阵元素结合之前，提取并将其外推到物理范围限制，然后将整个物理$ Q^2 $范围的形式因素进行预测，以预测半衰减的衰减率$γ（b_c^+ \ to b_s^0 \ to b_s^0 \ operline {\ ell} {\ ell} { \，\ text {s}^{ - 1} $和$γ（b_c^+ \ to b^0 \ overline {\ ell}ν_ {\ ell}）= 1.65（10）\ times 10^9 \，\ text \，\ text {s}^{s}^{ - 1} $。晶格QCD不确定性与这里的CKM不确定性相当。结果是从MILC协作量规配置计算出的相关函数的，其中包括一系列晶格间距，包括高度改进的交错夸克（HISQ）形式主义的动态海夸克的2+1+1个口味。 HISQ还用于Valence Light，angext and Charm Quarks的传播器。底部的夸克使用了两种不同的形式主义：非相关QCD（NRQCD）和重型hisq。检查这两种方法之间的协议是对我们在晶格上重夸克的策略的重要测试。从NRQCD和重型HISQ数据的链式拟合中，我们获得了差异衰减率$dγ/ d q^2 $以及集成值，以与未来的实验结果进行比较。
We present results of the first lattice QCD calculations of $B_c \to B_s$ and $B_c \to B_d$ weak matrix elements. Form factors across the entire physical $q^2$ range are then extracted and extrapolated to the physical-continuum limit before combining with CKM matrix elements to predict the semileptonic decay rates $Γ(B_c^+ \to B_s^0 \overline{\ell} ν_{\ell}) = 26.2(1.2) \times 10^9 \,\text{s}^{-1}$ and $Γ(B_c^+ \to B^0 \overline{\ell} ν_{\ell}) = 1.65(10) \times 10^9 \,\text{s}^{-1}$. The lattice QCD uncertainty is comparable to the CKM uncertainty here. Results are derived from correlation functions computed on MILC Collaboration gauge configurations with a range of lattice spacings including 2+1+1 flavours of dynamical sea quarks in the Highly Improved Staggered Quark (HISQ) formalism. HISQ is also used for the propagators of the valence light, strange, and charm quarks. Two different formalisms are employed for the bottom quark: non-relativistic QCD (NRQCD) and heavy-HISQ. Checking agreement between these two approaches is an important test of our strategies for heavy quarks on the lattice. From chained fits of NRQCD and heavy-HISQ data, we obtain the differential decay rates $dΓ/ d q^2$ as well as integrated values for comparison to future experimental results.
