The decay Z -> neutrino antineutrino photon in the Standard Model

TL;DR

This paper provides a detailed Standard Model calculation of the rare decay Z -> neutrino antineutrino photon, highlighting the dominant dipole contributions and estimating a very small branching ratio, leaving room for new physics searches.

Contribution

It presents the first complete one-loop calculation of this decay within the Standard Model, emphasizing the use of a nonlinear gauge and identifying key dipole contributions.

Findings

Branching ratio estimated at 7.16E-10

Main contributions from electric and magnetic dipole transitions

Results are four orders of magnitude below experimental bounds

Abstract

A complete study of the one-loop induced decay Z -> neutrino antineutrino photon is presented within the framework of the Standard Model. The advantages of using a nonlinear gauge are stressed. We have found that the main contributions come from the electric dipole and the magnetic dipole transitions of the Z gauge boson and the neutrino, respectively. We obtain a branching ratio B=7.16E-10, which is about four orders of magnitude smaller than the bound recentely obtained by the L3 collaboration and thus it leaves open a window to search for new physics effects in single-photon decays of the Z boson.