Speaker
Description
We consider a general, anomaly free U$(1)^\prime$ extension of the Standard Model (SM) where the neutrino mass is generated at tree level from the inverse seesaw mechanism.
After U$(1)^\prime$ symmetry breaking the mass of a neutral beyond the SM (BSM) gauge boson $(Z^\prime)$ is originated which can be produced it at high energy colliders.
The model contains three generations of heavy neutrinos which can interact with $Z^\prime$ and could be produced in pair at colliders.
A trilepton signature is very unique and clean when such pair production occurs at electron positron colliders from a TeV scale $Z^\prime$.
In this model we assign one pair of the degenerate sterile neutrinos as Dark Matter (DM) candidate whose relic density is generated by freeze-in mechanism. To reproduce the correct relic abundance we consider different mass regimes of the DM candidate and the $Z^\prime$. The production of DM can occur at different reheating temperatures in various scenarios depending on $Z^\prime$ and DM masses. Additionally, if the DM mass is greater than $1$ MeV and $Z^\prime$ is heavier than DM, the DM may decay into positron explaining the galactic $511$ keV line in the Milky Way observed by the INTEGRAL satellite.
