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arXiv 2203.11241hep-phhep-thnucl-exnucl-th
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BDMPS-Z形式中的介质修正的$g\to c\bar{c}$分裂函数

The medium-modified $g\to c\bar{c}$ splitting function in the BDMPS-Z formalism

Maximilian Attems, Jasmine Brewer, Gian Michele Innocenti, Aleksas Mazeliauskas, Sohyun Park, Wilke van der Schee, Urs Achim Wiedemann

摘要:

Baier-Dokshitzer-Mueller-Peigné-Schiff和Zakharov的形式主义确定了介质诱导胶子辐射对QCD等离子体中部分子分裂的修正。在这里,我们研究介质修改的胶子分裂成一个夸克-反夸克对在这个BDMPS-Z形式主义。我们推导出一个紧凑的路径积分公式,从任意数量的相互作用与介质的影响,以领先的顺序在$1/N_c^2$扩展。在$N=1$不透明度和鞍点近似下的分析揭示了两种现象:介质引起的相对夸克-反夸克对动量的增宽,增加了夸克-反夸克对的不变质量,以及介质增强了这种对的产生。我们注意到,这两种效应在数值上是相当大的,如果从介质的平均动量转移是可比的夸克质量。在超相对论性重离子碰撞中,这个条件对于粲夸克是满足的。因此,我们把我们的数值分析集中在$g\to c\bar{c}$的介质修改,虽然我们的推导同样适用于$g\to b\bar{b}$和胶子分裂成轻味夸克-反夸克对。

英文摘要:

The formalism of Baier-Dokshitzer-Mueller-Peigné-Schiff and Zakharov determines the modifications of parton splittings in the QCD plasma that arise from medium-induced gluon radiation. Here, we study medium-modifications of the gluon splitting into a quark--anti-quark pair in this BDMPS-Z formalism. We derive a compact path-integral formulation that resums effects from an arbitrary number of interactions with the medium to leading order in the $1/N_c^2$ expansion. Analyses in the $N=1$ opacity and the saddle point approximations reveal two phenomena: a medium-induced momentum broadening of the relative quark--anti-quark pair momentum that increases the invariant mass of quark--anti-quark pairs, and a medium-enhanced production of such pairs. We note that both effects are numerically sizeable if the average momentum transfer from the medium is comparable to the quark mass. In ultra-relativistic heavy-ion collisions, this condition is satisfied for charm quarks. We therefore focus our numerical analysis on the medium modification of $g\to c\bar{c}$, although our derivation applies equally well to $g\to b\bar{b}$ and to gluons splitting into light-flavoured quark--anti-quark pairs.

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