中科院数学与系统科学研究院
数学研究所
学术报告
数学物理研讨班
报告人： Amos Yarom (Technion)
题 目：Black hole supertranslations and hydrodynamic enstrophy
时 间：2024年5月10日（星期五）14：00-15：00
地 点：N224
摘 要：We study the relation between approximate horizon symmetries of AdS black branes and approximately conserved currents in their dual hydrodynamic description. We argue that the existence of an approximately conserved enstrophy current unique to 2
+1 dimensional fluid flow implies that AdS4 black branes possess a special class of approximate supertranslations (which we identify).
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报告人： Sebastian Waeber (Technion)
题 目： A transverse gradient expansion for holographic collisions
时 间：2024年5月10日（星期五）15：30-16：30
地 点：N224
摘 要：We introduce an approximation scheme to simplify the computation of collisions of localized shocks in five dimensional Anti-de Sitter space, used to model heavy ion collisions and quark gluon plasma formation. Several open questions regarding the early stages after heavy ion collisions, that holography can address, are now substantially simplified: Both the observation of a sizable transverse flow in holographic simulations of localized shock collisions, and the need to consider transverse energy density fluctuations to explain the observed large event-by-event fluctuations of flow observables during heavy ion collision, motivate to study collisions of localized holographic projectiles with a realistic granular, transverse structure. On the other hand, in order to decide whether the vorticity of the quark gluon plasma can explain the polarization of Lambda-Hyperions emitted during heavy ion collisions, one also needs to solve such collisions of projectiles with realistic aspect ratios to produce initial data for subsequent hydro evolutions. Solving holographic collisions of highly Lorentz-contracted shocks, while also taking into account transverse energy density fluctuations is computationally very challenging. We exploit the large disparity between transverse and longitudinal scales and expand Einstein equations in transverse gradients. One finds that already at first order results agree well with the exact solutions, while the approximation offers an order of magnitude improvement regarding run time and memory useage. We employ this technique to compute the vorticity and hydrodynamization time of the quark gluon plasma, starting from initial projectiles which correspond to realistic nuclear models of boosted heavy ions.
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