Dissipative effects in the effective field theory of inflation

• Autores: Lopez Nacir, Diana Laura; Porto, Rafael A.; Senatore, Leonardo; Zaldarriaga, Matias
• Año de publicación: 2012
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Cosmology of Theories beyond the SM; Space-Time Symmetries; Quantum Dissipative Systems
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

We generalize the effective field theory of single clock inflation to include dissipative effects. Working in unitary gauge we couple a set of composite operators, Oµν..., in the effective action which is constrained solely by invariance under time-dependent spatial diffeomorphisms. We restrict ourselves to situations where the degrees of freedom responsible for dissipation do not contribute to the density perturbations at late time. The dynamics of the perturbations is then modified by the appearance of ‘friction’ and noise terms, and assuming certain locality properties for the Green’s functions of these composite operators, we show that there is a regime characterized by a large friction term γ ≫ H in which the ζ-correlators are dominated by the noise and the power spectrum can be significantly enhanced. We also compute the three point function hζζζi for a wide class of models and discuss under which circumstances large friction leads to an increased level of non-Gaussianities. In particular, under our assumptions, we show that strong dissipation together with the required non-linear realization of the symmetries implies |fNL| ∼ γ c 2 sH ≫ 1. As a paradigmatic example we work out a variation of the ‘trapped inflation’ scenario with local response functions and perform the matching with our effective theory. A detection of the generic type of signatures that result from incorporating dissipative effects during inflation, as we describe here, would teach us about the dynamics of the early universe and also extend the parameter space of inflationary models
Fil: Lopez Nacir, Diana Laura. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentina
Fil: Porto, Rafael A.. Institute For Advanced Study; Estados Unidos. Columbia University; Estados Unidos
Fil: Senatore, Leonardo. University of Stanford. Physics Department; Estados Unidos. Institute For Advanced Study; Estados Unidos
Fil: Zaldarriaga, Matias. Institute For Advanced Study; Estados Unidos