Charged Fluid Dynamics in Scalar-Tensor Theories of Gravity with Torsion

TL;DR

This paper investigates the dynamics of a charged perfect fluid within scalar-tensor theories of gravity that include torsion, deriving equations of motion from an invariant action and confirming their consistency with gauge symmetries.

Contribution

It introduces a new variational framework for charged fluids in scalar-tensor gravity with torsion, ensuring gauge invariance and conformal symmetry.

Findings

Derived equations of motion for charged fluids with torsion.

Confirmed gauge invariance and consistency with spacetime symmetries.

Established equivalence between equations of motion and gauge identities.

Abstract

n scalar-tensor theories of gravity with torsion, the gravitational field is described in terms of a symmetric metric tensor $g$, a metric-compatible connection $\nabla$ with torsion, and a scalar field $\phi$. The main aim is to explore an interaction of a charged perfect fluid and a scalar field $\phi$ in a background electromagnetic and gravitational field described by \{$g$, $\nabla$, $\phi$\}. The interaction is based on an action functional $S_C$ of a charged perfect fluid that is invariant under global conformal rescalings. Using a variational principle, we obtain equations of motion for the charged perfect fluid. Moreover, we verify that these equations of motion are equivalent to the gauge identities obtained from the invariance of an action functional under spacetime dffeomorphisms and a local U(1) gauge group.