arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2011.14596hep-ph
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有限温度和密度下单圈盒积分的计算

Calculation of the one loop box integral at Finite Temperature and Density

A. S. Khvorostukhin

摘要:

在Nambu-Jona-Lasinio模型中计算非零温度和密度下的强子化、衰变或散射过程需要一些计算费曼图的技术。在单圈层次上分解费曼图导致出现具有一条、两条、三条和四条费米子线的基本积分。例如,计算$ππ$散射振幅需要计算具有四条费米子线的箱形图。在这项工作中,实部和虚部的盒积分在一个循环水平提供的形式适合于数值计算。所得到的表达式适用于温度、粒子质量和化学势的任何值。我们特别注意反常积分出现的条件,并对三条费米子线的结果\cite{Klevansky}进行了修正。结果,我们得到了粒子动量的可能值的约束。在箱积分的表达式中,对于费米子动量为零或共线的情况,导出了任意线数积分的一般公式。

英文摘要:

Calculation of hadronization, decay or scattering processes at non-zero temperatures and densities within the Nambu-Jona-Lasinio-like models requires some techniques for computation of Feynmann diagrams. Decomposition of Feynman diagrams at the one loop level leads to the appearance of elementary integrals with one, two, three, and four fermion lines. For example, evaluation of the $ππ$ scattering amplitude requires calculating a box diagram with four fermion lines. In this work, the real and imaginary parts of the box integral at the one loop level are provided in the form suitable for numerical evaluation. The obtained expressions are applicable to any value of temperature, particle mass, and chemical potential. We pay special attention to the conditions for the existence of the appearing improper integrals and correct the results \cite{Klevansky} for the three fermion lines. As a result, we have obtained constraints on possible values of particle momenta. Among the expressions for the box integral, the general formulas for the integral with an arbitrary number of lines are derived for the case with zero or collinear fermion momenta.

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