20-006 Searching for dark photons at the LHeC and FCC-he

Monica D’Onofrio, Oliver Fischer, Zeren Simon Wang

Physical Review D 101, 015020 (2020)

https://doi.org/10.1103/PhysRevD.101.015020

Abstract

Extensions of the Standard Model (SM) gauge group with a new U(1)_X predict an additional gauge boson. Through kinetic mixing with the SM photons featured by a coupling ε, the ensuing so-called dark photons γ', which acquire mass as a result of the breaking of the gauge group U(1)_X, can interact with the SM field content. These massive dark photons can therefore decay to pairs of leptons, hadrons, or quarks, depending on their mass m_γ' . In this work, we discuss searches for dark photons in the mass range around and below 1 GeV at the LHeC and FCC-he colliders. The signal is given by the displaced decays of the long-lived dark photon into two charged particles. We discuss the impact of conceivable irreducible (SM and machine-related) backgrounds and different signal efficiencies. Our estimates show that the LHeC and FCC-he can test a domain that is complementary to other present and planned experiments.

#publication #paper #Extensions_of_Gauge_Sector #Particle_decays #Particle_Interactions #Particle_Mixing&Oscillations #Particle_Phenomena #Particle_Production #Hypothetical_Gauge_bosons #Lepton-hadron_colliders