Classical Symmetries of Some Two-Dimensional Models Coupled to Gravity

TL;DR

This paper investigates how classical symmetries of two-dimensional models, specifically affine symmetries, are affected by coupling to gravity, finding that these symmetries remain unchanged while Virasoro symmetries do not generalize.

Contribution

It extends previous work on affine symmetries in flat space to models coupled with gravity, showing the invariance of these symmetries in the presence of gravitational backgrounds.

Findings

Symmetry algebras remain unchanged with gravity.

Field transformations depend on gravitational background.

Virasoro symmetries do not extend to gravitational theories.

Abstract

This paper is a sequel to one in which we examined the affine symmetry algebras of arbitrary classical principal chiral models and symmetric space models in two dimensions. It examines the extension of those results in the presence of gravity. The main result is that even though the symmetry transformations of the fields depend on the gravitational background, the symmetry algebras of these classical theories are completely unchanged by the presence of arbitrary gravitational backgrounds. On the other hand, we are unable to generalize the Virasoro symmetries of the flat-space theories to theories with gravity.