While the Standard Model remains the best theory to describe elementary particles and their interactions, there are still some unresolved issues that cannot be addressed within its current framework. Right handed neutrinos are introduced to the Standard Model to explain the observed active neutrino masses. If CP is violated during their radiative decays an asymmetry between two circularly–polarised photons can be generated. The CP asymmetry is somehow connected to circular polarisation. Therefore, observations of such polarised signal potentially lead to a measurement of the CP violation in the process. Here, we provide the connection between these two asymmetries for both, Dirac and Majorana neutrinos. We then apply this formalism to a minimal seesaw model and give the CP asymmetry in terms of a series of Jarlskog-like parameter. We also provide the formalism to study the changes in the polarisation of photons at any energy, since the intensity of such circularly polarised signal could change as it propagates through the Universe.
Finally, we pay attention to the dark matter paradigm. We discuss the capture of dark matter in compact stellar objects as complementary to direct detection searches.
We particularly work with white dwarfs (WD) since due to their abundance and high temperatures they one of the best observed compact objects proposed as cosmic laboratories for studying physical processes happening at very extreme conditions that cannot be achieved at terrestrial laboratories. Using an observed WD from the Messier 4 globular cluster, we set constraints on the DM interactions
