The LISA forecast on a smooth crossover beyond the Standard Model through the scalar-induced gravitational waves

TL;DR

This paper explores how the LISA gravitational wave detector could identify signals from a hypothetical smooth crossover in the early universe beyond the Standard Model, using scalar-induced gravitational waves and Fisher forecast analysis.

Contribution

It demonstrates the potential detectability of a high-energy crossover via SIGWs in the LISA frequency range and links it to primordial black holes and dark matter.

Findings

A crossover at ~100 TeV can produce detectable GW signals in LISA's range.

The properties of the crossover can be constrained if primordial scalar perturbations are sufficiently large.

The associated PBH mass could account for dark matter.

Abstract

Supposing the Laser Interferometer Space Antenna (LISA) gravitational wave (GW) detector, we exhibit the detectability of a hypothetical smooth crossover in the early universe beyond the Standard Model of particle physics through the scalar-induced gravitational wave (SIGW) in terms of the Fisher forecast. A crossover at $\sim100\,\mathrm{TeV}$ can leave a signal on the GW spectrum in the $\sim\mathrm{mHz}$ frequency range, the sweet spot of the LISA sensitivity. These possibilities are also interesting in the primordial black hole (PBH) context as the associated PBH mass $\sim10^{22}\,\mathrm{g}$ lies at the window to explain the whole dark matter. We found that the properties of the crossover can be well determined if the power spectrum of primordial scalar perturbations are as large as $\sim5\times10^{-4}$ on the corresponding scale $\sim10^{12}\,\mathrm{Mpc^{-1}}$.