论文标题
$ b_c \ rightarrow j/ψ$整体$ q^2 $范围rattice qcd范围
$B_c \rightarrow J/ψ$ Form Factors for the full $q^2$ range from Lattice QCD
论文作者
论文摘要
我们介绍了$ b_c \ rightarrow j/ψ$向量和轴向矢量形式的第一个晶格QCD测定。这些将启用有关$ b_c $ emeptonic衰减比率的实验信息，以转换为$ v_ {cb} $的值。我们的计算涵盖了衰减的完整物理$ q^2 $范围，并使用非扰动的晶格电流。我们使用高度改进的交错夸克（HISQ）动作，用于所有价值夸克（Valence Quarks）的第二代Gluon野外配置的MILC集团，包括$ u $，$ d $，$ s $和$ c $ c $ c $ hisq sea quarks。我们的HISQ重夸克的质量高于$ c $；我们能够在最好的晶格上达到$ b $。这使我们能够绘制出对重夸克质量的依赖性，并在$ b $的连续限制中确定结果。我们使用我们的形式因素来构建$ b_c^ - \ rightArrow j/ψμ^ - \barν_μ$的差异速率，并获得$ 7 \％$不确定性的总费率：$γ（b_c^ - \ rightArrow j/c/ψμ^ - \barν_μ） 1.73（12）\ times 10^{13}〜\ mathrm {s}^{ - 1} $。包括$ v_ {cb} $，$η_{\ Mathrm {ew}} $和$τ_{b_c} $的值，对于此0.0150（11）（10）（10）（3）〜的衰减模式的分支分数，来自lattice qcd，$η__ \ qut mathrmmmatrm {ew} $τ_{b_c} $。
We present the first lattice QCD determination of the $B_c \rightarrow J/ψ$ vector and axial-vector form factors. These will enable experimental information on the rate for $B_c$ semileptonic decays to $J/ψ$ to be converted into a value for $V_{cb}$. Our calculation covers the full physical $q^2$ range of the decay and uses non-perturbatively renormalised lattice currents. We use the Highly Improved Staggered Quark (HISQ) action for all valence quarks on the second generation MILC ensembles of gluon field configurations including $u$, $d$, $s$ and $c$ HISQ sea quarks. Our HISQ heavy quarks have masses ranging upwards from that of $c$; we are able to reach that of the $b$ on our finest lattices. This enables us to map out the dependence on heavy quark mass and determine results in the continuum limit at the $b$. We use our form factors to construct the differential rates for $B_c^- \rightarrow J/ψμ^- \barν_μ$ and obtain a total rate with $7\%$ uncertainty: $Γ(B_c^-\rightarrow J/ψμ^-\barν_μ)/|η_{\mathrm{EW}}V_{cb}|^2 = 1.73(12)\times 10^{13} ~\mathrm{s}^{-1}$. Including values for $V_{cb}$, $η_{\mathrm{EW}}$ and $τ_{B_c}$ yields a branching fraction for this decay mode of 0.0150(11)(10)(3) ~with uncertainties from lattice QCD, $η_\mathrm{EW}V_{cb}$ and $τ_{B_c}$ respectively.
