Q-balls Formation and the Production of Gravitational Waves With Non-minimal Gravitational Coupling

TL;DR

This paper explores how non-minimal gravitational couplings of the Affleck-Dine field influence Q-balls formation and gravitational wave production, revealing new scalar potential forms and simulation results.

Contribution

It introduces a method to realize non-minimal couplings for scalar fields in supergravity and studies their effects on Q-balls and gravitational wave generation.

Findings

Q-balls can form with non-negative K parameter when non-minimal coupling is present.

Gravitational wave production depends on the non-minimal coupling parameter ξ.

New scalar potential form in Einstein frame derived from non-minimal couplings.

Abstract

We propose to introduce non-minimal couplings of Affleck-Dine (AD) field to gravity by adding the coupling of AD field to the Ricci scalar curvature. As the Jordan frame supergravity always predict $|\Phi|^2 {\cal R}/6$ type coupling for scalars with canonical kinetic terms, we propose a way to realize the required $c_0|\Phi|^2 {\cal R}$-type couplings with generic $c_0$ for canonical complex scalar fields after SUSY breaking. The impacts of such non-minimal gravitational couplings for AD field is shown, especially on the Q-balls formation and the associated gravitational wave (GW) productions. New form of scalar potential for AD field in the Einstein frame is obtained. By numerical simulations, we find that, with non-minimal gravitational coupling to AD field, Q-balls can successfully form even with the choice of non-negative $K$ parameter for $\xi>0$. The associated GW productions as well as their dependences on the $\xi$ parameter are also discussed.