BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Masahide Yamaguchi (Institute for Basic Science (IBS) and Tokyo In stitute of Technology (TIT)) DTSTART:20260615T090000Z DTEND:20260615T100000Z DTSTAMP:20260423T024825Z UID:NKUA-HEP/56 DESCRIPTION:Title: Cosmological first-order phase transitions: tunneling at finite temperat ure\nby Masahide Yamaguchi (Institute for Basic Science (IBS) and Toky o Institute of Technology (TIT)) as part of NKUA HEP Seminars\n\n\nAbstrac t\nCosmological phase transitions\, especially first order phase transitio ns\, have attracted renewed interest as potential sources of gravitational waves. Accurately predicting the resulting gravitational wave signal requ ires a reliable estimate of the transition rate\, which is governed by a s addle-point configuration known as the bounce solution. The seminal work o f Coleman\, Glaser\, and Martin established that at zero temperature\, any nontrivial bounce solution to the equations of motion that minimizes the Euclidean action is O(D)-symmetric in D-dimensional spacetime. At finite t emperature\, however\, it has not been proven that an O(D-1)-symmetric bou nce solution in the spatial directions indeed yields the minimal Euclidean action\, despite this assumption being widely used in the literature. In this talk\, we extend the Coleman–Glaser–Martin analysis to finite tem perature. We rigorously prove that for a broad class of scalar potentials\ , any saddle-point configuration with the least action is necessarily O(D- 1)-symmetric and monotonic in the spatial directions. This result provides a firm mathematical foundation for the symmetry properties widely assumed in studies of thermal vacuum decay and cosmological phase transitions.\n LOCATION:https://researchseminars.org/talk/NKUA-HEP/56/ END:VEVENT END:VCALENDAR