Opening the parameter space of sub-GeV inelastic dark matter through parity violation

Sub-GeV dark matter (DM) has emerged as a particularly compelling target in light of the persistent null results from conventional DM searches. While s-wave annihilating DM candidates with masses below the GeV are strongly constrained by indirect-detection bounds, inelastic scenarios can naturally evade these limits. In this work, we show that parity violation can play an important role in inelastic DM models featuring long-lived excited states by inducing small diagonal couplings that significantly relax experimental constraints. A precise determination of the excited-state abundance is essential for assessing the phenomenology of such models. To this end, we solve the integrated Boltzmann equation, fully accounting for up- and down-scattering with electrons and positrons as well as darksector conversion processes. Using the resulting abundance, we update the viable parameter space in light of the most recent experimental constraints and demonstrate that parityviolating interactions can reopen broad regions of parameter space that would otherwise be excluded. Moreover, the forthcoming LDMX experiment will probe a significant portion of the parameter space. ... mehrThe framework developed in this work can be readily applied to other exothermic sub-GeV DM scenarios.