Higgs-Induced Gravitational Waves: the Interplay of Non-Minimal Couplings, Kination and Top Quark Mass

TL;DR

This paper investigates how Higgs-induced gravitational waves, generated through curvature-driven instabilities during a stiff expansion era, can reveal high-energy Higgs potential features and inform early Universe reheating.

Contribution

It presents a minimal scenario linking Higgs dynamics, gravitational wave production, and vacuum stability without relying on quantum vacuum instability.

Findings

Gravitational wave background correlates with inflationary scale and top quark mass.

Detection could reveal Higgs potential features at high energies.

Scenario distinguishes between stable and unstable electroweak vacuum cases.

Abstract

We explore a minimal scenario where the sole Standard-Model Higgs is responsible for reheating the Universe after inflation, produces a significant background of gravitational waves and maintains the full classical stability of the electroweak vacuum. As the Higgs self-coupling runs toward negative values at high energy scales, a non-minimal interaction with curvature during a stiff background expansion era drives the Higgs fluctuations closer to the instability scale. This curvature-induced tachyonic instability leads to an intense production of Higgs particles, accompanied by a stochastic gravitational-wave background. The characteristic features of such signal can be directly correlated to the inflationary scale, the non-minimal coupling parameter and the top quark Yukawa coupling. We distinguish between three possible scenarios: absolute stability with low top quark masses, potential vacuum instability, and absolute stability with new physics above the instability scale. Our findings suggest that the detection of a peaked background of gravitational waves together with its inflationary tail has the potential to unveil the features of the Higgs effective potential at very high energy scales while providing a minimal explanation for the reheating phase and the emergence of the Standard-Model plasma in the early Universe. Unlike other studies in the literature, the generation of gravitational waves in our scenario does not depend on the quantum instability of the Standard Model vacuum.