Совместный семинар отделов «Теория фундаментальных взаимодействий» и «Теория адронного вещества в экстремальных условиях»

Дата и время: четверг, 29 июля 2021 г., в 16:00

Место: Онлайн-семинар в Zoom, Лаборатория теоретической физики им. Н.Н. Боголюбова

Тема семинара: «Convergence of hydrodynamic series and dual gravity»

Докладчик: А. О. Старинец (Центр теоретической физики им. Рудольфа Пайерлса, Оксфордский университет, Великобритания)

Аннотация:

In quantum field theory at finite temperature and density, hydrodynamic modes (e.g. sound waves) are characterised by gapless dispersion relations usually considered as infinite series in powers (or fractional powers) of the spatial momentum squared. These series naturally arise within the classical hydrodynamic gradient expansion understood as an effective theory. Motivated by the search for limits of a reliable hydrodynamic description, we discuss the problem of determining the radii of convergence of such series and its dependence on the coupling. Using dual gravity methods, at least for some theories it is possible to compute the radius of convergence at infinite and large but finite coupling. The obstruction to convergence is caused by the level-crossing phenomenon in the quasinormal spectra of dual black holes. Our calculation shows that the radius of convergence in these theories is a piecewise continuous function of the coupling with an overall tendency to decrease with the coupling decreasing.