SEMINAIRE MERCREDI 14 SEPTEMBRE 2005
14 heures
Salle Séminaire 5
Centre de Physique Théorique
Marseille-Luminy

Christian Jaekel
Université de Sao Paulo (Brésil)

Title: Stability and related properties of vacua and ground states

Abstract: We consider the formal non relativistc limit (nrl) of the
:\phi^4:_{s+1} relativistic quantum field theory (rqft), where s is the
space dimension. We show that (thermodynamic) stability is broken in
the formal nrl for s=2, due to the mass renormalization of :\phi^4:_3,
despite the fact that (thermodynamic) stability of the full
relativistic model holds for both s=1 and s=2. More precisely, we show
that for s=2 thermodynamic stability of the nrl is broken for
sufficienty large but finite ultarviolet cutoff, due to the infinite
mass renormalization of the former theory. In this framework we also
compare stability by local perturbations, complete passivity and the
existence of local annihilators of the vacuum, for rqft on the one
hand, and the formal nrl, on the other.

(with Walter Wreszinski)