We present a next-to-leading order (NLO) relativistic correction to Bc → J/ψ tensor form factors within nonrelativistic QCD (NRQCD). We also consider complete Dirac bilinears c̄Γb with 4 × 4 matrices Γ = 1,γ5,γμ,γμγ5,σμν in the b → c transition. The relation among different current form factors is given and it shows that symmetries emerge in the heavy bottom quark limit. For a phenomenological extension, we propose to extract the long-distance matrix elements (LDMEs) for Bc meson from the recent HPQCD lattice data and the NLO form factors at large momentum recoil.

中文翻译：

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Bc → J/ψ 大动量反冲下的张量形状因子

我们提出了一个次领先阶 (NLO) 相对论修正乙C → Ĵ/ψ非相对论 QCD (NRQCD) 内的张量形状因子。我们还考虑完全狄拉克双线性C̄Γb和4 × 4矩阵Γ = 1,γ5,γμ,γμγ5,σμν在里面b → C过渡。给出了不同电流形状因子之间的关系，表明在重底夸克极限中出现了对称性。对于现象学扩展，我们建议提取长距离矩阵元素（LDME）乙C来自最近的 HPQCD 晶格数据和大动量反冲下的 NLO 形状因子的介子。