Sterile neutrinos with non-standard secret interactions imprints on Cosmic Microwave Background anisotropies

7th Young Researcher Meeting

Forastieri, F.^1,2

Dipartimento di Fisica e Scienze della Terra, Universita degli Studi di Ferrara, via Giuseppe Saragat 1, Ferrara

I-44122, Italy^1

Istituto Nazionale di Fisica Nucleare, Sezione di Ferrara, via Giuseppe Saragat 1, Ferrara

I-44122, Italy^2

关键词: Big bang nucleosynthesis;    Cosmic microwave background anisotropies;    Cosmic microwave background radiation;    Laboratory experiments;    Oscillation frequency;    Relativistic energy;    Scattering effects;    Sterile neutrinos;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/841/1/012002/pdf
DOI  :  10.1088/1742-6596/841/1/012002

来源: IOP

【 摘 要 】

Short baseline laboratory (SBL) anomalies have shown preference for light sterile neutrinos with eV masses. These particles, if confirmed, would be produced in the early universe and would add their contribution to the relativistic energy density basically increasing the effective number of extra relativistic species (Neff). It has been shown that when the matter potential produced by the sterile interactions becomes smaller than the vacuum oscillation frequency, sterile neutrinos are plentifully produced by the scattering effects in the sterile neutrino sector. This behaviour, however, leads to a ΔNeff 1 which is in tension at 3 - 5σ with the actual constraints given by the latest Cosmic Microwave Background radiation (CMB) observations. In order to avoid the thermalization of eV sterile neutrinos in the early universe, secret interactions between the sterile and active sectors mediated by a massive vector boson (MXW) have been proposed. In particular, interactions mediated by a gauge boson having MX 0.1 eV and seem to save the cosmological constraints coming from big-bang nucleosynthesis (BBN) and mass bounds. In this framework, cosmological observations represent a powerful tool to constrain neutrino physics complementary to laboratory experiments. In particular, observations of the CMB have the potential to constrain the properties of relic neutrinos, as well as of additional light relic particles in the universe. In this work we present the effects of the strength of the interaction on the neutrino fluid perturbations and on the CMB anisotropies power spectrum.