Searching for Dark Pions with the MoEDAL-MAPP Detector at the LHC

Abstract

We investigate the potential for detecting pion-like dark matter within the framework of a Strongly Interacting Massive Particle (SIMP) model using the MoEDAL Apparatus for Penetrating Particles (MAPP) at the LHC. The model, motivated by Chiral Perturbation Theory, features milli-charged dark pions that couple to Standard Model particles via kinetic mixing with a dark photon. Production channels considered include Drell--Yan pair production and photon fusion via the Wess--Zumino--Witten term, the latter providing a distinctive three-body final state signature. Cross-sections are computed using MadGraph and WHIZARD for a range of dark pion masses, decay constants, and dark $Z$ boson masses. Sensitivity projections for MAPP-1 during the High-Luminosity LHC phase are presented under a background-free assumption, showing competitive reach into previously unexplored parameter space for milli-charged dark pseudoscalars. These results highlight the complementary role of MoEDAL-MAPP in probing dark sector models and motivate further detector-level simulations to refine exclusion limits.