Eur. Phys. J. C (2020) 80: 197
https://doi.org/10.1140/epjc/s10052-020-7756-6

Regular Article - Theoretical Physics

Gravitational waves from scale-invariant vector dark matter model: probing below the neutrino-floor

¹ Department of Physics, Lorestan University, Khorramabad, Iran
² School of Particles and Accelerators, Institute for Research in Fundamental Sciences (IPM), Tehran, Iran

^* e-mail: mohamadnejad.a@lu.ac.ir

Received: 27 July 2019
Accepted: 19 February 2020
Published online: 3 March 2020

Abstract

We study the gravitational waves (GWs) spectrum produced during the electroweak phase transition in a scale-invariant extension of the Standard Model (SM), enlarged by a dark gauge symmetry. This symmetry incorporates a vector dark matter (DM) candidate and a scalar field (scalon). Because of scale invariance, the model has only two independent parameters and for the parameter space constrained by DM relic density, strongly first-order electroweak phase transition can take place. In this model, for a narrow part of the parameter space, DM-nucleon cross section is below the neutrino-floor limit, and therefore, it cannot be probed by the future direct detection experiments. However, for a benchmark point from this narrow region, we show the amplitude and frequency of phase transition GW spectrum fall within the observational window of space-based GW detectors such as eLISA.