DeCAF Seminar Series:

Abstract: Sub-GeV dark matter provides a well motivated alternative to conventional WIMP scenarios, especially in light of the persistent absence of signals in standard searches. However, thermal candidates below the GeV scale are strongly constrained by indirect detection whenever annihilations proceed through unsuppressed s-wave channels. Inelastic dark matter can naturally evade part of these bounds, although scenarios with long-lived excited states remain constrained by exothermic down scattering signals and late-time energy injection. This talk discusses how parity violation modifies this picture in pseudo-Dirac inelastic dark matter with a dark photon mediator. Small parity-violating effects induce suppressed diagonal interactions that are almost irrelevant for setting the relic abundance, but can remain efficient at late times in the dark sector, depleting the excited-state population after thermal freeze-out. This depletion substantially weakens direct and indirect detection constraints, reopening viable regions for MeV-scale dark matter with keV–MeV mass splittings. The talk also discusses the experimental prospects of this scenario, showing that future experiments, in particular LDMX, can test a significant fraction of the remaining parameter space.

Speaker Bio: Javier Silva Malpartida is a PhD candidate in High Energy Physics at the Pontificia Universidad Católica del Perú. His research focuses on dark matter phenomenology, with particular interest in non-standard cosmological histories, thermal and non thermal dark matter production mechanisms, and sub-GeV dark matter models.