On universality of the coupling of neutrinos to Z

Abstract

We employ an effective Lagrangian approach and use LEP data to place severe bounds on universality violations of the couplings of ${\nu }_e$, ${\nu }_{\mu }$, and ${\nu }_{\tau }$ to the $Z$ boson. Our results justify the assumption of universality in these couplings that is usually made, as for example in the analysis of solar neutrinos detected at SNO.

Comments: 8 pages, no figures. A few comments added. It matches version to be published in PRD