Parity violation in radiative emission of neutrino pair from metastable states of heavy alkaline earth atoms

Abstract

Macro-coherent atomic de-excitation involving a neutrino pair emission, radiative emission of neutrino pair (RENP) $|e\rangle \rightarrow |g\rangle + \gamma +\nu_i \nu_j$ (with $\gamma$ a photon and $\nu_i$ a neutrino mass eigenstate), is a new experimental tool to determine undetermined neutrino parameters such as the smallest neutrino mass and distinction of Majorana and Dirac neutrinos. The best way to prove that the atomic RENP process accompanied by unseen neutrino pair involves weak interaction is to measure parity violating (PV) quantities. We quantitatively study how this is achieved. The basic mechanism of how a favorable situation for PV may arise from the fundamental electroweak theory (extended to incorporate finite neutrino masses) is emphasized and calculation of dependence of PV observables on applied magnetic field is worked out for heavy target atoms of alkaline earth like level structure such as Sr, Yb, Hg, Xe. Numerically calculated parity violating rates and asymmetry are presented for Yb $J=2 \rightarrow 0$ and $J=0 \rightarrow 0$ RENP.