The Mu2e experiment, currently under construction at Fermilab (USA), will search for the charged-lepton flavor violating neutrino-less conversion of negative muons into electrons in the field of an aluminum nucleus. A conversion signal would require physics beyond the Standard Model, and the aim of Mu2e is to reach a sensitivity four orders of magnitude better than previous experiments.
To...
MeV-scale thermal dark matter has its abundance set during the highly non-trivial epochs of neutrino decoupling and electron annihilation. We study this problem by solving the Boltzmann equations of multiple interacting sectors being both relativistic and non-relativistic. We show that the freeze-out of thermal MeV dark particles has subtle effects on Neff, as well as on other cosmological...