Enhanced nuclear-spin-dependent parity-violation effects using the HgH199 molecule

Electron interactions with the nuclear-spin-dependent (NSD) parity-nonconserving (PNC) anapole moment are strongly enhanced within heteronuclear diatomic molecules. A 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 sophisticated numerical calculation of the circular polarization parameter P = 2 Im(E1(P)(Nc))/M1 approximate to 3 x 10(-6 )kappa for the (2)Sigma(1)(/2) -> (2)pi(1/2) optical transition of HgH, where K 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. Therefore we show that the proposed measurement should be sensitive enough to extract the 199 Hg anapole moment and shed light on the underlying theory of hadronic parity violation.