Invisible decays of vector Charmonia and Bottomonia to determine the Weak Mixing Angle at quarkonia scale

TL;DR

This paper calculates the invisible decay rates of vector quarkonia into neutrinos to measure the weak mixing angle at quarkonium energy scales, potentially revealing neutrino properties beyond the Standard Model.

Contribution

It introduces a method to determine the weak mixing angle using quarkonium decays and explores implications for neutrino nature and non-standard interactions.

Findings

Branching fractions depend on the weak vector coupling of heavy quarks.

Potential to distinguish Dirac and Majorana neutrinos through decay measurements.

Provides a new approach to probe neutrino properties at quarkonium scales.

Abstract

We compute the branching fractions of vector quarkonia ($V_Q=J/\psi, \psi', \Upsilon(nS)$) decays into neutrino pairs, considering both Dirac and Majorana types, within the Standard Model (SM) and beyond. The vector nature of quarkonium states yields a decay width in the SM that depends upon the weak vector coupling of the heavy quark, offering the possibility to measure the weak mixing angle at the quarkonia mass scales. If neutrinos have non-standard neutral weak couplings, this could help to distinguish the nature of neutrinos in principle.