A search is reported for long-lived dark photons with masses between 0.1 GeV and 15 GeV, from exotic decays of Higgs bosons produced via vector-boson-fusion. Events that contain displaced collimated Standard Model fermions reconstructed in the calorimeter or muon spectrometer are probed. This search uses the full LHC Run 2 (2015-2018) data sample collected in proton-proton collisions at s√=13 TeV, corresponding to an integrated luminosity of 139 fb−1. Dominant backgrounds from Standard Model processes and non-collision sources are estimated by using data-driven techniques. The observed event yields in the signal regions are consistent with the expected background. Upper limits on the Higgs boson to dark photon branching fraction are reported as a function of the dark-photon mean proper decay length or of the dark-photon mass and the coupling between the Standard Model and the potential dark sector. This search is combined with previous ATLAS searches obtained in the gluon-gluon fusion and \textit{WH} production modes. A branching fraction above 10\% is excluded at 95\% CL for a 125 GeV Higgs boson decaying into two dark photons for dark-photon mean proper decay lengths between 173 and 1296 mm and mass of 10 GeV.
- Search for light long-lived neutral particles from Higgs boson decays via vector-boson-fusion production from pp collisions at s√=13 TeV with the ATLAS detector
- ATLAS Collaboration (Author)Aram Apyan (Author) - Brandeis University, Martin A. Fisher School of PhysicsJames Bensinger (Author) - Brandeis University, Martin A. Fisher School of PhysicsGabriella Sciolla (Author) - Brandeis University, Martin A. Fisher School of Physics
- The European Physical Journal C, Vol.84, 719
- Springer
- 9924380786501921
- Martin A. Fisher School of Physics
- Journal article