Time-reversal symmetry violation in molecules induced by nuclear magnetic quadrupole moments

TL;DR

This paper investigates how nuclear magnetic quadrupole moments in certain molecules can reveal violations of time-reversal symmetry, potentially leading to tighter constraints on fundamental CP-violating parameters.

Contribution

It provides calculations of T,P-odd effects induced by nuclear MQMs in various molecules, highlighting their potential for improved measurements of fundamental symmetry violations.

Findings

Nuclear MQMs significantly amplify T,P-odd effects in molecules with deformed nuclei.

Calculated effects in molecules like TaN, ThO, and HfF+ suggest enhanced sensitivity for symmetry violation tests.

Comparison with TlF shows potential for improved limits on nuclear CP-violation parameters.

Abstract

Recent measurements in paramagnetic molecules improved the limit on the electron electric dipole moment (EDM) by an order of magnitude. Time-reversal (T) and parity (P) symmetry violation in molecules may also come from their nuclei. We point out that nuclear T,P-odd effects are amplified in paramagnetic molecules containing deformed nuclei, where the primary effects arise from the T,P-odd nuclear magnetic quadrupole moment (MQM). We perform calculations of T,P-odd effects in the molecules TaN, ThO, ThF$^+$, HfF$^+$, YbF, HgF, and BaF induced by MQMs. We compare our results with those for the diamagnetic TlF molecule, where the T,P-odd effects are produced by the nuclear Schiff moment. We argue that measurements in molecules with MQMs may provide improved limits on the strength of T,P-odd nuclear forces, on the proton, neutron and quark EDMs, on quark chromo-EDMs, and on the QCD $\theta$-term and CP-violating quark interactions.