Big Bang Nucleosynthesis as a probe of non-standard neutrino interactions and non-unitary three-neutrino mixing

Abstract

In this work we investigate the impact of two phenomenological Beyond the Standard Model (BSM) scenarios concerning the role of neutrinos in the early universe: non-standard neutrino interactions (NSI) and non-unitary three-neutrino mixing. We evaluate the impact of these frameworks on two key cosmological observables: the effective number of relativistic neutrino species (\Neff), related to neutrino decoupling, and the abundances of light elements produced at Big Bang Nucleosynthesis (BBN). For the first time, neutrino CC-NSI with quarks and non-unitary three-neutrino mixing are studied in the context of BBN, and the constraints on such interactions are found to be remarkably restrictive. In particular, the BBN limits are competitive with the ones derived from terrestrial experiments for the non-diagonal CC-NSI parameter ${\epsilon }_{e\alpha }^{udV}$, with $\alpha \ne e$ and for the non-unitarity parameter ${\alpha }_{22}$. In the case of non-unitarity, the combination between neutrino decoupling and BBN imposes stringent constraints that can either mildly favour the existence of New Physics (NP), or reinforce the SM, depending on the choice of the experimental nuclear rates involved in the BBN calculation. These results stress the already noted need for further nuclear rates measurements in order to obtain more robust BBN theoretical predictions.

22 pages, 5 figures, 1 table. Version accepted for publication in JCAP

References in corpus (22)

• Primordial Nucleosynthesis: from precision cosmology to fundamental physics
• Relic neutrino decoupling with flavour oscillations revisited
• Towards a precision calculation of $N_{\mathrm{eff}}$ in the Standard Model II: Neutrino decoupling in the presence of flavour oscillations and finite-temperature QED
• Neutrino decoupling including flavour oscillations and primordial nucleosynthesis
• A precision calculation of relic neutrino decoupling
• General bounds on non-standard neutrino interactions
• The primordial deuterium abundance of the most metal-poor damped Lyman-alpha system
• Constraining Nonstandard Neutrino-Electron Interactions
• A new tension in the cosmological model from primordial deuterium?
• EMPRESS. VIII. A New Determination of Primordial He Abundance with Extremely Metal-Poor Galaxies: A Suggestion of the Lepton Asymmetry and Implications for the Hubble Tension
• Thermalisation of sterile neutrinos in the early Universe in the 3+1 scheme with full mixing matrix
• Primordial Deuterium after LUNA: concordances and error budget
• The Impact of New d(p,γ)He3 Rates on Big Bang Nucleosynthesis
• Scrutinizing CKM unitarity with a new measurement of the $K_{\mu 3}/K_{\mu 2}$ branching fraction
• Effects of non-standard neutrino-electron interactions on relic neutrino decoupling
• Indications for a Nonzero Lepton Asymmetry from Extremely Metal-Poor Galaxies
• Resolving conclusions about the early Universe requires accurate nuclear measurements
• Cosmological radiation density with non-standard neutrino-electron interactions
• Non-unitary three-neutrino mixing in the early Universe
• Neutron Lifetime Anomaly and Big Bang Nucleosynthesis
• Big Bang Nucleosynthesis and Neutrino Cosmology
• Sensitivity of reactor experiments to nonstandard neutrino interactions in beta decay rates