Speaker
Description
Spurred by a variety of neutrino oscillation anomalies, a strong interest has arisen in recent years in non-standard neutrino interactions (both active and sterile). The effects of such interactions have been also investigated within extensions of the standard cosmological model.
The work focuses on the possibility to characterize and constrain the parameter space of the so-called Majoron models of neutrino mass generation through new cosmological observables not explored so far, like polarization and cosmic birefringence. The study is developed through the use of the Quantum Boltzmann Equation (QBE) formalism (see Kosowsky 1996; Sigl and Raffelt 1993), a theoretical tool allowing us to track the evolution of particle number densities by taking into account correlations between particles with different discrete quantum numbers, like flavor or helicity.
We investigated the evolution of the cosmic microwave background (CMB) photons density matrix induced by the energy transfer between neutrino and photon mediated by a pseudoscalar particle (in both the limits of massless and massive), considering both tree-level diagrams and 1-loop corrections. The resulting Botlzmann hierarchy, written in terms of the CMB Stokes' parameters, shows a clear dependence on the parameters of the model, thus hinting at another probe of fundamental physics complementary to laboratory experiments.
The main equations resulting from this work provide two main effects: a modification in the optical depth of the cosmic fluid and a coupling between different polarization modes of the photon background.
| Poster prize | Yes |
|---|---|
| Given name | Nicola |
| Surname | Barbieri |
| First affiliation | Univeristy of Ferrara |
| Institutional email | nicola.barbieri@unife.it |
| Gender | Male |
| Collaboration (if any) | Massimiliano Lattanzi, Nicola Bartolo and Moslem Zarei |
