Condensates in Relativistic Scalar Theories

TL;DR

This paper investigates the structure, coherence, and topological features of condensates in relativistic scalar theories with different symmetries, revealing how conserved charges influence their decay and spatial homogeneity.

Contribution

It provides a detailed analysis of the condensate's properties in O(N) symmetric theories, highlighting the role of conserved charges and topological defects in their dynamics.

Findings

For N>1, condensates carry nearly maximal conserved charge density.

Conserved charges impede condensate decay and prevent full spatial homogeneity.

Topological defects appear for N<=4 but do not dominate the power spectrum tail.

Abstract

Scalar field theory with large infrared initial occupancy develops very large deep-infrared occupancy, which locally resembles a Bose-Einstein condensate. We study the structure and spatial coherence of this condensate. The O(N) symmetric theory with N>1 is qualitatively different than N=1. We explain the thermodynamical reason why, for N>1, the condensate locally carries nearly maximal conserved charge density. We also show how this property impedes the condensate's decay, and we show that it prevents the condensate from ever becoming fully spatially homogeneous. For N <= 4 the condensate can carry topological defects, but these do not appear to control the large-k tail in its power spectrum, which is the same for N=8 where there are no topological defects.