Tail effects of self-interacting scalar fields

TL;DR

This paper studies how quartic self-interactions of a nearly massless scalar field influence binary system dynamics, revealing deviations from General Relativity and identifying bounds on self-coupling strength.

Contribution

It introduces a detailed analysis of tail effects and bounds on scalar self-coupling in binary systems within scalar-tensor theories.

Findings

Bound on self-coupling: λ ≲ (β^2 G_N M_⊙^2)^{-1}

Detection of small periastron advance due to tail interactions

Deviations from General Relativity at conservative level

Abstract

We consider the effects of quartic self-interactions on the dynamics of a binary system due to a (nearly) massless scalar field conformally coupled to matter. We investigate the deviations from General Relativity at the conservative level and put a bound on the self-coupling $ \lambda \lesssim (\beta^2 G_N M_\odot^2)^{-1}$ where $\beta$ is the conformal coupling of the scalar to matter. We also consider the radiative sector where we use the Schwinger-Keldysh formalism to find the tail interactions which couple the multipoles of the binary system and induce a small advance of the periastron.