Talk detail

Participant	Giacomini, Alex
Institution	Universidad Austral de Chile - Campus Isla Teja, Edificio Puguin - Valdivia - Los Rios - Chile

Session	QF2	Accepted	Yes	Order	5	Time	15:45	15'
Talk	Oral abstract	Title	The Gribov problem in curved space-time
Coauthors	Anabalon, Andres ; Canfora, Fabrizio ; Oliva, Julio
Abstract	It is a well known fact that for non-Abelian gauge theories the gauge fixing is only locally well defined. This means that when the gauge potential is large with respect to a suitable norm, gauge fixing ambiguities appear which would imply an overcounting of states in the path integral. This fact is known in literatura as the Gribov problem. In order to avoid such an overcounting Gribov proposed to restrict the path integral to the region of the potential space which is free of ambiguities. The implementation of this procedure dramatically modifies the propagator of the gluon in the infrared which becomes suppressed. This fact suggests that the Gribov approach to path integral is a promising canditate for the explanation of the confiment problem. Up to now the overwhelming majority of research on this subject has been done in in flat space-time. Only very recently the gauge fixing problem on curved space-times has begun to attract the attention of the scientific community. The purpose of this talk is to show some of the effects of non-trivial space-time geometry on the gauge fixing problem and its physical implications for QCD, Abelian gauge theories, and for the gravitational degrees of freedom.
Pdf file

Session	AT1	Accepted	Yes	Order	8	Time	17:00	10'
Talk	Oral abstract	Title	Dynamical compactification in Einstein-Gauss-Bonnet gravity from geometric frustration
Coauthors	Canfora, Fabrizio ; Giacomini, Alex ; Pavluchenko Sergey
Abstract	In this paper we study dynamical compactification in Einstein-Gauss-Bonnet gravity from arbitrary dimension for generic values of the coupling constants. We showed that, when the curvature of the extra dimensional space is negative, for any value of the spatial curvature of the four dimensional space-time one obtains a realistic behavior in which for asymptotic time both the volume of the extra dimension and expansion rate of the four dimensional space-time tend to a constant. Remarkably, this scenario appears within the open region of parameters space for which the theory does not admit any maximally symmetric (4+D)- dimensional solution, which gives to the dynamical compactification an interpretation as geometric frustration. In particular there is no need to fine-tune the coupling constants of the theory so that the present scenario does not violate "naturalness hypothesis". Moreover we showed that with increase of the number of extra dimensions the stability properties of the solution are increased.
Pdf file