General relativity limit of the scalar-tensor theories for traceless matter field

TL;DR

This paper investigates the limit of scalar-tensor theories as the coupling parameter approaches infinity, revealing it does not recover general relativity in the case of traceless matter, and provides an exact radiation solution in cosmology.

Contribution

It demonstrates that the $\omega(\phi) o \infty$ limit does not lead to general relativity for traceless matter and derives an exact radiation solution in scalar-tensor cosmology.

Findings

The limit $\omega(\phi) o \infty$ does not reduce to GR for traceless matter.

An exact radiation solution in scalar-tensor cosmology is obtained.

Scalar-tensor theories behave differently than expected in the high coupling limit.

Abstract

$\omega(\phi) \to \infty$ limit of scalar tensor theories are studied for traceless matter source. It is shown that the limit $\omega(\phi) \to \infty$ does not reduce a scalar tensor theory to general relativity. An exact radiation solution of scalar tensor cosmology under Nordtvedt conditions is obtained for flat Friedmann universe.