Centre de Physique Théorique

Agenda

Vendredi 16 décembre 2016

11h00 – 13h00, Amphi 5 du CPT

Phase Transition Theory and applications to Biophysics

Matteo Gori

Soutenance de thèse de Matteo Gori (directeur de thèse : Marco Pettini)

11h30 – 12h30, Amphi 5 du CPT

Thermodynamics of quantum fields in actual finite size systems : When Casimir meets Linde

Sylvain Mogliacci (UCT_CERN, University of Cape Town)

 !! attention heure exceptionnelle !!

Physique des particules

Abstract

Motivated by the need for a more quantitative description of the late stage heavy ion collisions, I review a surprising recent development which concerns the thermodynamics of quantum fields, in systems with actual finite volumes.

For the sake of my argument, I focus on a massless/massive single component non-interacting scalar field, even though the present idea is applicable to any renormalizable field theory such as Quantum Chromodynamics.

I then demonstrate how thermodynamic quantities can be investigated from a different perspective, inspired by a more realistic approach to the finiteness of the size of such systems. Besides significant finite volume corrections, a number of interesting features naturally follow from the treatment of the volume of the system. Of particular interest, the absence of any infrared divergence, plaguing conventional finite temperature perturbation theory, sets a new and natural solution to the so-called infrared Linde problem.

The review, performed with different spatial compactifications, encompasses various thermodynamic quantities such as the pressure and the squared speed of sound --- all having non trivial temperature dependences, despite the absence of interaction at leading order.

14h00 – 15h00, Amphi 5 du CPT

Structure géométrique des espaces de géodésiques

Patrick Iglesias-Zemmour (I2M)

Physique mathématique

Résumé

Lorsque l’espace des géodésiques d’une variété riemannienne est une variété, il est bien connu qu’il est équipé naturellement d’une structure symplectique. Mais que reste-t-il de cela lorsque les géodésiques ne forment plus une variété, comme dans le cas du tore par exemple ? C’est ce dont nous discuterons.

Agenda