报告题目：Emergence of long-range correlations in quark-gluon plasma

报 告 人：苏楠博士（德国法兰克福大学理论物理研究所）

报告时间：10月26日（周一）14：00

报告地点：理科楼B315

报告摘要：The quark-gluon plasma created in ultra-relativistic heavy-ion collisions behaves novelly as a strongly coupled liquid, rather than a weakly coupled gas predicted theoretically. This has been a key challenge for the theory community over the past 15 years, and long-range correlations are crucial missing ingredients for a systematic approach based on the underlying theory of quantum chromodynamics (QCD). In this talk, I discuss a novel way to incorporate long-range correlations to thermal QCD by systematically including the (chromo)magnetic scale g^2T — which is missing in conventional approaches — in the setup. As a result, a novel massless mode is generated by the magnetic scale which are long-range in nature, while the conventional massive quasiparticle modes generated by the (chromo)electric scale gT are reproduced. The residue of this massless mode is nonpositive at all temperatures, which consequently gives rise to positivity violation in the quark spectral functions. This demonstrates profound impacts of confinement effects on thermal quark collective excitations, which manifest genuine long-range correlations in the system. As an application of this scenario, I show the results of bulk and shear viscosities from kinetic theory calculations whose behaviors are in line with a strongly coupled liquid.