Shedding flavor on dark via freeze-in: U(1)B-3Ligauged extensions

Abstract

AbstractWe consider a singlet fermionic dark matter (DM)χin a gauged U(1)B-3Liextension of the Standard Model (SM), withi ⋲ e, μ, τ, and derive bounds on the allowed parameter space, considering its production via freeze-in mechanism. The DM communicates with the SM only through flavorful vector-portalZB3Ldue to its non-trivial chargexunder U(1)B-3Li, which also guarantees the stability of the DM over the age of the Universe forx≠ {±3/2, ±3}. ConsideringZB3Lto lie within the mass range of a few MeV up to a few GeV, we obtain constraints on the gauge couplinggB3Lfrom the requirement of producing right relic abundance. Taking limits from various (present and future) experimental facilities, e.g., NuCal, NA64, FASER, SHiP into account, we show that the relic density allowed parameter space for the frozen in DM can be probed withgB3L≳ 10-8for bothmχ<mZB3L/2 andmχ≳mZB3L, whilegB3L≲ 10-8remains mostly unconstrained. We also briefly comment on the implications of neutrino mass generation via Type-I seesaw and anomalous (g-2)μin context withB-3Lμgauged symmetry.