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arXiv 0802.4364hep-ph
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夸克-胶子等离子体中快重夸克的碰撞能量损失

Collisional energy loss of a fast heavy quark in a quark-gluon plasma

Stephane Peigne, Andre Peshier

摘要:

讨论了在高夸克能量E >> M^2/T的极限下,重夸克穿过夸克-胶子等离子体的平均碰撞能量损失dE/dx,其中M为夸克质量,T >> M为等离子体温度.在固定耦合近似中,在首阶dE/dx \propto α_s ^2,系数在数值上增强。由热部分子的t-通道散射产生的软对数是众所周知的,但是由u-通道交换产生的共线对数以前被忽略了。我们还确定了这些领先的常数。然后,我们将dE/dx的计算推广到运行耦合的情况。我们估计剩余的理论不确定性dE/dx,这原来是相当大的RHIC条件下。最后,我们指出了dE/dx与QCD德拜质量之间的一个近似关系,并由此导出了所有夸克能量下dE/dx的一个上界。

英文摘要:

We discuss the average collisional energy loss dE/dx of a heavy quark crossing a quark-gluon plasma, in the limit of high quark energy E >> M^2/T, where M is the quark mass and T >> M is the plasma temperature. In the fixed coupling approximation, at leading order dE/dx \propto α_s^2, with a coefficient which is logarithmically enhanced. The soft logarithm arising from t-channel scattering off thermal partons is well-known, but a collinear logarithm from u-channel exchange had previously been overlooked. We also determine the constant beyond those leading logarithms. We then generalize our calculation of dE/dx to the case of running coupling. We estimate the remaining theoretical uncertainty of dE/dx, which turns out to be quite large under RHIC conditions. Finally, we point out an approximate relation between dE/dx and the QCD Debye mass, from which we derive an upper bound to dE/dx for all quark energies.

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