We present the first calculation of the jet transport coefficient $\widehat{q}$ in quenched and ($2+1$)-flavor QCD on a 4D Euclidean lattice. The lightlike propagation of an energetic parton is factorized from the mean square gain in momentum transverse to the direction of propagation, which is expressed in terms of the thermal field-strength field-strength correlator. The leading-twist term in its operator product expansion is calculated on the lattice. Continuum extrapolated quenched results, and full QCD estimates based on unrenormalized lattice data, over multiple lattice sizes, are compared with (non)perturbative calculations and phenomenological extractions of $\widehat{q}$. The lattice data for $\widehat{q}$ show a temperature dependence similar to the entropy density. Within uncertainties, these are consistent with phenomenological extractions, contrary to calculations using perturbation theory.

中文翻译：

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射流输运系数q^in 晶格QCD

我们提出了射流传输系数的第一个计算$\widehat{q}$在淬火和（$2+1$)-在 4D 欧几里得晶格上的风味 QCD。高能部分的类光传播是从垂直于传播方向的动量的均方增益中分解出来的，它用热场强场强相关器表示。其算子乘积展开中的前导项是在格上计算的。连续外推淬火结果，以及基于非重整化晶格数据的完整 QCD 估计，在多个晶格尺寸上，与（非）微扰计算和现象学提取进行比较$\widehat{q}$. 晶格数据为$\widehat{q}$显示出类似于熵密度的温度依赖性。在不确定性范围内，这些与现象学提取一致，与使用微扰理论的计算相反。