A matrix phase for the phi^4 scalar field on the fuzzy sphere

TL;DR

This paper investigates the critical behavior of the phi^4 scalar field theory on the fuzzy sphere, revealing a new phase with spontaneously broken rotational symmetry due to non commutative geometry effects.

Contribution

It introduces a novel matrix phase in the scalar field theory on the fuzzy sphere, providing insights into UV-IR mixing and non commutative geometry effects.

Findings

Identification of a new matrix phase with broken rotational symmetry

Analysis of UV-IR mixing effects in non commutative field theory

Numerical evidence of phase transitions in the fuzzy sphere model

Abstract

The critical properties of the real phi^4 scalar field theory are studied numerically on the fuzzy sphere. The fuzzy sphere is a matrix (non commutative) discretisation of the algebra of functions on the usual two dimensional sphere. It is also one of the simplest examples of a non commutative space to study field theory on. Aside from the usual disordered and uniform phases present in the commutative scalar field theory, we find and discuss in detail a new phase with spontaneously broken rotational invariance, called matrix phase because the geometry of the fuzzy sphere, as expressed by the kinetic term, becomes negligible there. This gives some further insight on the effect of UV-IR mixing, the unusual behaviour which arises naturally when taking the commutative limit of a non commutative field theory.