Spontaneous Symmetry Probing

par Federico Piazza (APC Paris)

jeudi 31 janv. 2013, 11:00 → 12:00 Europe/Paris

Auditorium Vivargent (Annecy-le-Vieux)

I will discuss the general implications of symmetries in the case of time-dependent field states. In particular, I will be interested in field configurations that spontaneously ``probe'' the symmetry -- or one of the symmetries -- in the sense that they evolve in time along a symmetry direction in field space. This situation captures certain essential features of generic early universe inflationary models without committing too much with their microphysical details. The same formalism applies also to other -- apparently disparate -- situations, such as many-body systems at finite chemical potential. When the Goldstone theorem is generalized to this situation we find new results in the case in which the symmetry in question is part of a larger non-commutative symmetry group: The non-commuting and broken conserved currents interpolate massive (instead of massless) excitations. We derive an exact non-perturbative expression for their gaps.