Speaker
Description
In this talk, I will discuss our recent work on the implications of the neutrino fog in dark matter direct detection experiments, motivated by the recent observation of coherent elastic neutrino--nucleus scattering (CE$\nu$NS) from solar $^8$B neutrinos by the XENONnT collaboration. Neutrino fluxes, primarily of astrophysical origin, constitute an irreducible background for dark matter searches. As detector sensitivities improve, this background leads to the so-called neutrino fog, a regime in which dark matter signals become increasingly difficult to distinguish from neutrino-induced nuclear recoils. Within this context, we consider scenarios in which mediators beyond the Standard Model contributes to either CE$\nu$NS or dark matter--nucleus scattering. The mediator is assumed to be scalar, vector, or axial-vector in nature, thereby covering both spin-independent and spin-dependent interactions, and may be either heavy or light. Using the latest nuclear recoil data from XENONnT, we derive constraints on the WIMP--nucleon scattering cross section and the WIMP mass. We further compute the neutrino fog within this framework and discuss how the sensitivity of direct detection experiments approaches this background in the few-GeV mass range, where neutrino-induced recoils can mimic light dark matter signals. We also comment on how the interpretation of results depends on the mediator mass: while heavy mediators allow a description in terms of the zero-momentum-transfer WIMP--nucleon cross section, light mediators require constraints to be expressed in the multidimensional parameter space involving the couplings, mediator mass, and dark matter mass. Overall, our results highlight that light mediators can substantially modify both the dark matter exclusion limits and the neutrino background, motivating dedicated investigations of such scenarios in future direct detection searches.