Cutflow analysis of dark photons to 4-muon final states in an extended minimal supersymmetric model at the LHC

Abstract

This paper presents a simplified cutflow analysis of an extended Minimal Supersymmetric Standard Model featuring a dark sector mediated by a dark photon γ_D. Under an additional U(1)_D symmetry, the γ_D kinetically mixes with the Standard Model photon and decays into leptons. Signal events for the process pp → h → 2n₁ → 2γ_D + 2n_D (where γ_D →  μ⁺μ⁻) were generated using MadGraph5 interfaced with Pythia8. Complementary CheckMATE scans across several γ_D mass points revealed that most remain unconstrained by previous searches. A custom Rivet analysis applied the cutflow, introducing angular separation requirements derived from the signal topology. Applying cuts on the angular separations of muons from the same γ_D effectively isolated lower-mass signals from the background, but heavily suppressed higher-mass scenarios due to inherent decay kinematics. These results highlight both the utility and limitations of simplified cutflows in discriminating signals from backgrounds in multilepton final states, particularly in the low-mass regime.