Event characterization of dark bosons via exotic Higgs decays with final states of displaced dimuons in high luminosity era of the LHC

TL;DR

This paper explores the potential of detecting long-lived dark vector bosons and dark Higgs bosons through exotic Higgs decays into displaced dimuons at the LHC, using simulations and projected data from future runs.

Contribution

It introduces a comprehensive analysis of exotic Higgs decay channels involving dark bosons, including production mechanisms, decay modes, and sensitivity estimates for future LHC data.

Findings

Projected sensitivity for detecting displaced dimuons up to 7500 mm

Simulation of branching fractions using MadGraph5_aMC@NLO

Estimation of search reach with different integrated luminosities

Abstract

We investigate the potential reach of a search for a long-lived/prompt dark vector boson $Z_D$, also called dark $Z$, and a prompt dark Higgs boson $h_D$ through exotic decays of the observed Higgs boson $h$ into either $Z_DZ_D$, $h_Dh_D$, or $ZZ_D$ with $Z$ being the hypercharge gauge boson. The $Z_D$ production through the Higgs portal is completed via one of two mechanisms, kinetic mixing of $Z_D$ with $Z$ and the mixing of $h_D$ with $h$. All production modes of $h$ are considered, while the branching fractions are calculated in Monte Carlo simulation using the {\textsc{MadGraph5}}\_aMC@NLO v2.7.2 framework. We focus on a final state of multiple dimuons, displaced up to \mbox{7500 mm}, where the muons can be reconstructed without vertex constraint using data from ATLAS and CMS detectors to be collected in Run~3. Integrated luminosities of 137, 300, and 3000 fb$^{-1}$ for Run~2, Run~3, and high luminosity run (HL-LHC), respectively, are used for estimating the expected search sensitivity of the Large Hadron Collider to each of the decay modes.