Enhanced nuclear spin dependent parity violation effects using the 199HgH molecule

TL;DR

This paper proposes a novel optical rotation experiment using the HgH molecule to significantly enhance the detection sensitivity of nuclear-spin-dependent parity violation effects, enabling insights into hadronic parity violation.

Contribution

The study provides the first complete relativistic coupled cluster calculation of the optical rotation parameter in HgH, demonstrating 2-3 orders of magnitude sensitivity improvement over previous atomic experiments.

Findings

Enhanced sensitivity to NSD PNC effects in HgH by 2-3 orders of magnitude.

Calculated the optical rotation parameter for HgH's specific transition.

Proposed experiment can extract the $^{199}$Hg anapole moment.

Abstract

Electron interactions with the nuclear-spin-dependent (NSD) parity non-conserving (PNC) anapole moment are strongly enhanced within heteronuclear diatomic molecules. A novel, low-energy optical rotation experiment is being proposed with the aim of observing NSD PNC interactions in HgH. Based on the relativistic coupled cluster method we present a complete calculation of the circular polarization parameter $P = 2\,\textrm{Im}(E1_{PNC})/M1 \approx 3 \times 10^{-6}\; \kappa$ for the $^2\Sigma_{1/2} \to ^2\Pi_{1/2}$ optical transition of HgH, where $\kappa$ is a dimensionless constant determined by the nuclear anapole moment. This provides an improvement in sensitivity to NSD PNC by 2 -- 3 orders of magnitude over the leading atomic Xe, Hg, Tl, Pb and Bi optical rotation experiments, and shows that the proposed measurement will be sensitive enough to extract the $^{199}$Hg anapole moment and shed light on the underlying theory of hadronic parity violation.