Evolution of neutrino mass-mixing parameters in matter with non-standard interactions

Abstract

Abstract We explore the role of matter effect in the evolution of neutrino oscillation parameters in the presence of lepton-flavor-conserving and lepton-flavor-violating neutral-current non-standard interactions (NSI) of the neutrino. We derive simple approximate analytical expressions showing the evolution of mass-mixing parameters in matter with energy in the presence of standard interactions (SI) and SI+NSI (considering both positive and negative values of real NSI parameters). We observe that only the NSI parameters in the (2,3) block, namely ε μτ and (γ − β) ≡ (ε ττ − ε μμ ) affect the modification of θ 23. Though all the NSI parameters influence the evolution of θ 13, ε eμ and ε eτ show a stronger impact at the energies relevant for DUNE. The solar mixing angle θ 12 quickly approaches to ∼ 90 ° with increasing energy in both SI and SI+NSI cases. The change in ∆ m 21 , m 2 $$ {m}_{21,m}^2 $$ is quite significant as compared to ∆ m 31 , m 2 $$ {m}_{31,m}^2 $$ both in SI and SI+NSI frameworks for the energies relevant for DUNE baseline. Flipping the signs of the NSI parameters alters the way in which mass-mixing parameters run with energy. We demonstrate the utility of our approach in addressing several important features related to neutrino oscillation such as: a) unraveling interesting degeneracies between θ 23 and NSI parameters, b) estimating the resonance energy in presence of NSI when θ 13 in matter becomes maximal, c) figuring out the required baselines and energies to have maximal matter effect in ν μ → ν e transition in the presence of different NSI parameters, and d) studying the impact of NSI parameters ε μτ and (γ − β) on the ν μ → ν μ survival probability.

Keywords

• Beyond Standard Model
• Neutrino Physics