In this research we consider a U(1)X gauge Square Compact Mirror boson acting as a dark matter candidate.The vector dark matter (DM) gets mass when a complex singlet scalar breaks the gauge symmetry spontaneously, adding a second Higgs boson to the spectra.The dark matter candidates communicate with the SM particles via a scalar-Higgs portal.
In this work, we concentrate on the masses of the vector dark matter and the scalar mediator below 10 GeV, aka light dark matter.Although we assume thermal freeze-out for the vector DM using the zero-moment of the full Boltzmann equation to calculate the relic abundance, we explore the effects of the second-moment when the vector DM annihilates resonantly.As typically light DM is highly sensitive to CMB bounds, we focus L-CYSTEINE on two thermal mechanisms which alleviate this bound: dark matter annihilation via forbidden channels and near a pole.
Other bounds from colliders, thermalization conditions, beam-dump experiments, and astrophysical observations are imposed.Taking into account all the bounds including the direct detection upper limits, the viable space is achieved.