Non-sterile right-handed neutrinos
Right-handed neutrinos have no charges under the Standard Model symmetries, and so are usually regarded as stirle. However, if lepton number nonconservation is allowed, there exist effective operatros of dimension as low as five that provide them with several interesting interactions; one of them is a magnetic moment that makes it possible to directly produce them. This could be especially important in astrophysical scenarios, where right-handed neutrinos could provide additional cooling mechanisms for red giants or supernovae, and also in collider experiments, where they should have been observed. As this has not happened (yet), we have several sources of bounds on the effective interaction. I will discuss these and other phenomenological issues of the effective Lagrangian, and will present a simple model which generates these interactions at the one-loop level.