Matter Effect on Neutrino Oscillations from the violation of Universality in Neutrino Neutral Current Interactions

Abstract

The violation of lepton-flavor-universality in the neutrinoZ interactions can lead to extra matter effects on neutrino oscillations at high energies, beyond that due to the usual charged-current interaction of the electron-neutrino. We show that the dominant effect of the violation is a shift in the effective value of θ23. This is in contrast to the dominant effect of the charged-current interaction which shifts θ12 and θ13. The shift in θ23 will be difficult to observe if the value of sin2(2θ23) is too close to one. However, if the value of sin2(2θ23) is as small as 0.92, then a Fermilab →Hyper-Kamiokande experiment can potentially place a constraint on universality violation at the 1% level after 5 years of data taking.