Inflation and nonequilibrium renormalization group

Abstract

We study de spectrum of primordial fluctuations and the scale dependence of the inflaton spectral index due to self-interactions of the field. We compute the spectrum of fluctuations by applying nonequilibrium renormalization group techniques.

Quantum renormalization group

“…where the bare potential, U B (φ), is an even polynomial, starting beyond the quadratic order. The reduced density matrix of the blocked theory can be found by integrating out the unobserved modes and it defines the COTP effective theory according to (14), where the integration extends over modes with spatial momentum |p| < k and the blocked action is defined by Eqs. ( 15)-( 16) with m 2 = m 2 B and the bare CTP path integral,…”

“…The generalization of the Wegner-Houghton equation, corresponding to a sharp cutoff where the evolution of the blocked action is followed in the local potential approximation was the subject of the earliest publications [13] which was restricted to the pure state contributions. The mixed state terms were kept in [14] where the renormalized trajectory was considered for a scalar field theory, brought into contact with a heat bath. But the friction force has already been introduced in the bare theory; hence, the mixed state contributions appear in a regular manner, without a gap.…”

Renormalizing Open Quantum Field Theories

“…The functional renormalization group method was already applied in the CTP formalism to follow the coarse graining [21][22][23], addressing a quantum dot [24], open electronic systems [25], the transport processes [26], the damping [27], the inflation [28], quantum cosmology [29] and critical dynamics [30][31][32][33]. Furthermore, it can describe the behavior of the Bose-Einstein condensate [34][35][36], the form of the spectral function [37,38], or real time dynamics of gauge theories [39].…”

Renormalizing open quantum field theories

“…The functional renormalization group method has already been applied in the CTP formalism to follow the coarse graining [3], addressing a quantum dot [4], open electronic systems [5], the transport processes [6], the damping [7], the inflation [8], quantum cosmology [9] and critical dynamics [10]. Furthermore it can describe the behaviour of the Bose-Einstein condensate [11], the form of the spectral function [12], or real time dynamics of gauge theories [13].…”