Probing low-mass vector bosons with parity nonconservation and nuclear anapole moment measurements in atoms and molecules

TL;DR

This paper investigates how hypothetical low-mass vector bosons could cause parity-violating effects in atoms and nuclei, using calculations and experimental data to set new constraints on such particles over a wide mass range.

Contribution

It provides the first comprehensive calculations of vector-mediated PNC effects in multiple atoms and nuclei, and establishes significantly improved bounds on vector boson interactions.

Findings

New constraints on vector boson-mediated P-violating interactions

Enhanced limits over previous experiments across a broad mass spectrum

Demonstrated the sensitivity of atomic and nuclear PNC measurements to new physics

Abstract

In the presence of P-violating interactions, the exchange of vector bosons between electrons and nucleons induces parity-nonconserving (PNC) effects in atoms and molecules, while the exchange of vector bosons between nucleons induces anapole moments of nuclei. We perform calculations of such vector-mediated PNC effects in Cs, Ba$^+$, Yb, Tl, Fr and Ra$^+$ using the same relativistic many-body approaches as in earlier calculations of standard-model PNC effects, but with the long-range operator of the weak interaction. We calculate nuclear anapole moments due to vector boson exchange using a simple nuclear model. From measured and predicted (within the standard model) values for the PNC amplitudes in Cs, Yb and Tl, as well as the nuclear anapole moment of $^{133}$Cs, we constrain the P-violating vector-pseudovector nucleon-electron and nucleon-proton interactions mediated by a generic vector boson of arbitrary mass. Our limits improve on existing bounds from other experiments by many orders of magnitude over a very large range of vector-boson masses.