Shining light through the Higgs portal with $\gamma\gamma$ colliders

TL;DR

High-energy gamma-gamma colliders, as potential modes of future electron-positron colliders, could uniquely probe hidden dark sectors via the Higgs portal with high precision, surpassing other planned facilities.

Contribution

This study demonstrates the superior sensitivity of gamma-gamma colliders to Higgs portal dark sectors above the invisible decay threshold, highlighting their potential for new physics discovery.

Findings

Gamma-gamma colliders can probe dark sectors more precisely than other colliders.

They can explore Higgs portal parameters related to electroweak phase transition.

Potential to detect signals of first-order electroweak phase transition.

Abstract

High-energy $\gamma\gamma$ colliders constitute a potential running mode of future $e^+ e^-$ colliders such as the ILC and CLIC. We study the sensitivity of a high-energy $\gamma\gamma$ collider to the Higgs portal scenario to a hidden sector above the invisible Higgs decay threshold. We show that such $\gamma\gamma$ collisions could allow to probe the existence of dark sectors through the Higgs portal comparatively more precisely than any other planned collider facility, from the unique combination of sizable cross-section with clean final state and collider environment. In addition, this search could cover the singlet Higgs portal parameter space yielding a first-order electroweak phase transition in the early Universe.