Gravitational wave signals from short-lived topological defects in the MSSM

TL;DR

This paper studies gravitational wave signals produced by topological defects formed from flat directions in the MSSM, linking these signals to supersymmetric parameters and early Universe conditions.

Contribution

It demonstrates that topological defects from flat directions can generate detectable gravitational waves, providing a new probe of supersymmetry and early Universe physics.

Findings

Topological defects form at the end of inflation and decay at the start of oscillation.

Numerical calculations of gravitational signals relate to supersymmetric scale and reheating temperature.

Gravitational wave observations can reveal details about higher dimensional operators.

Abstract

Supersymmetric theories, including the minimal supersymmetric standard model, usually contain many scalar fields whose potentials are absent in the exact supersymmetric limit and within the renormalizable level. Since their potentials are vulnerable to the finite energy density of the Universe through supergravity effects, these flat directions have nontrivial dynamics in the early Universe. Recently, we have pointed out that a flat direction may have a positive Hubble induced mass term during inflation whereas a negative one after inflation. In this case, the flat direction stays at the origin of the potential during inflation and then obtain a large vacuum expectation value after inflation. After that, when the Hubble parameter decreases down to the mass of the flat direction, it starts to oscillate around the origin of the potential. In this paper, we investigate the dynamics of the flat direction with and without higher dimensional superpotentials and show that topological defects, such as cosmic strings and domain walls, form at the end of inflation and disappear at the beginning of oscillation of the flat direction. We numerically calculate their gravitational signals and find that the observation of gravitational signals would give us information of supersymmetric scale, the reheating temperature of the Universe, and higher dimensional operators.