Higgs-boson production in association with a Dark Photon in $e^+ e^-$ collisions

TL;DR

This paper investigates the potential to detect Higgs bosons produced alongside massless dark photons in electron-positron collisions, exploring signals that could reveal new physics beyond the Standard Model.

Contribution

It introduces a novel analysis of Higgs-dark photon associated production in $e^+ e^-$ collisions, considering model-independent sensitivities at future colliders.

Findings

Potential to observe Higgs-dark photon signals at ILC and FCC-ee

Estimates of collider sensitivities for the $H o b\bar{b}$ channel

Analysis of background processes and signal significance

Abstract

We study the production of a Higgs boson recoiling from a massless invisible system in $e^ + e^ -$ collisions. This is a quite distinctive signature that can arise when the Higgs boson is produced in association with a massless dark photon, which can happen in BSM scenarios foreseeing an extra unbroken $U(1)$ gauge group. Dark photons can indeed acquire effective couplings to the Higgs boson as occurs in models recently proposed to generate exponentially-spread Yukawa couplings. We analyze the signal and corresponding backgrounds for $H\to b\bar{b}$, and estimate ILC and FCC-ee sensitivities in a model-independent way.