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SUMMARY:QFT-gravity Seminar: Thomas Apostolidis
DESCRIPTION:Toward the CompactHedron: Bounds on Neutron Stars from Microsco
 pic Principles\n\nAbstract: Much is still unknown about neutron stars\, in
 cluding their equation of state\, which describes the matter in their inte
 rior. Next-generation gravitational-wave detectors can help shed light on 
 this question by measuring the so-called Love numbers\, which encode the t
 idal response of a compact object to an external perturbation. In this tal
 k\, I will investigate the implications of causality and positivity for th
 e tidal Love numbers of gravitating objects. I will work within the framew
 ork of point-particle effective field theory\, where the Love numbers corr
 espond to the Wilson coefficients of operators constructed from the curvat
 ure tensor. I will show that requiring the tidal response to be retarded a
 nd to decay at high frequencies\, together with the assumption of passivit
 y\, leads to nontrivial bounds on the Love numbers. I will then outline th
 e computation of dynamical Love numbers through fourth order in the freque
 ncy expansion\, using dimensional regularization\, for a representative se
 t of neutron-star equations of state\, and show that\, in the low-compactn
 ess regime\, the bounds translate into constraints on the fundamental osci
 llation mode of the star. While the focus is primarily on conservative sys
 tems\, I will also discuss how the bounds are modified in the presence of 
 dissipation. These results lay the groundwork for a systematic framework t
 o derive bounds on compact objects from fundamental principles.
URL:https://www.imperial.ac.uk/events/214276/qft-gravity-seminar-thomas-apo
 stolidis/
DTSTART;TZID=Europe/London:20261113T120000
DTEND;TZID=Europe/London:20261113T130000
LOCATION:H503\, Huxley Building\, South Kensington Campus\, Imperial Colleg
 e London\, London\, SW7 2AZ\, United Kingdom
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