Using parity-nonconserving spin-spin coupling to measure the Tl nuclear anapole moment in a TlF molecular beam

TL;DR

This paper proposes using a TlF molecular beam to measure the nuclear anapole moment through parity-nonconserving spin-spin coupling, employing advanced relativistic computational methods to connect experimental signals with nuclear properties.

Contribution

It introduces a novel experimental approach combined with relativistic calculations to measure the Tl nuclear anapole moment via PNC spin-spin coupling in TlF.

Findings

Calculated PNC spin-spin coupling constant agrees with experimental data.

Proposed rf field method enables measurement of nuclear anapole moments.

Relativistic methods effectively link experimental signals to nuclear properties.

Abstract

An experiment utilizing a TlF molecular beam is being developed by the CeNTREX collaboration to search for hadronic interactions that violate both time-reversal (T) and parity (P) invariance. Here we propose to use the same beam to look for a T-invariance conserving but P-nonconserving (PNC) effect induced by the anapole moment of the Tl nucleus, via a vector coupling of the two nuclear spins in TlF. To measure the nuclear anapole moment, the dc electric and magnetic fields in CeNTREX are replaced by rf fields resonant with a nuclear spin flip transition. We adapt the relativistic coupled cluster method in a combination with relativistic density functional theory for the calculation of the molecular PNC spin-spin vector coupling constant that links the experimental signal with the anapole moment. The value of the P-conserving spin-spin coupling constant calculated within the same approach is found to be in good agreement with available experimental data.