Speaker
Description
We investigate the potential reach at the large hadron collider (LHC) of a search for a long-lived dark vector boson, also called a dark $Z$ or $Z_D$, through exotic decays of the standard-model Higgs boson $h$ into either $Z_DZ_D$ or $ZZ_D$. Besides, we investigate a decay of $h$ into two dark Higgs bosons $h_Dh_D$ with each $h_D$ decaying into a pair of $Z_D$'s. We consider the production of $h$ via gluon-gluon fusion (ggF) and use production cross sections from the literature for Runs 2 and 3 of the LHC, calculated to a combination of next-to-next-to-next-to-leading order with QCD corrections (N$^3$LO QCD) and next-to-leading order with electroweak corrections (NLO EW). The $Z_D$ production through the Higgs portal is completed via one of two mechanisms, kinetic mixing of $Z_D$ with the hypercharge boson and the mixing of $h_D$ with $h$. The branching fractions are calculated to NLO and scanned over the relevant mixing parameters and particle masses in Monte Carlo (MC) simulation using the MadGraph5_aMC@NLO v2.7.2 framework. Emphasis is given to a final state of dimuons, displaced up to 7500 mm, where the muons can be reconstructed without vertex constraint using data from the ATLAS and CMS detectors to be collected in Run 3 of the LHC. Integrated luminosities of 137, 300, and 3000 fb$^{-1}$ for Run 2, Run 3, and High Luminosity (HL) era, respectively, of the LHC are used for estimating the expected search sensitivity of the LHC to each decay mode. Finally, we investigate the kinematics of the displaced dimuons and the $Z_D$ decay lengths in the detectors.
| In-person participation | No |
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