${\cal{P,T}}$-Violating and Magnetic Hyperfine Interactions in Atomic Thallium

TL;DR

This paper provides advanced calculations of hyperfine interactions and ${ m P,T}$-violating constants in atomic thallium, reducing theoretical uncertainties but not tightening constraints on fundamental ${ m P,T}$-odd parameters.

Contribution

It introduces state-of-the-art configuration interaction and coupled cluster calculations for ${ m P,T}$-odd interactions in thallium, improving accuracy of theoretical constants.

Findings

Reduced uncertainties in hyperfine and ${ m P,T}$-odd constants.

No new constraints on electron EDM or scalar-pseudoscalar coupling.

Precise values for interaction constants in thallium ground state.

Abstract

We present state-of-the-art configuration interaction and coupled cluster calculations of the electron electric dipole moment, the nucleon-electron scalar-pseudoscalar, and the magnetic hyperfine interaction constants ($\alpha_{d_e}, \alpha_{C_S}, A_{||}$, respectively) for the thallium atomic ground state $^2P_{1/2}$. Our present best values are $\alpha_{d_e} = -559 \pm 28$, $\alpha_{C_S} = 6.77 \pm 0.34$ $[10^{-18} e$ cm$]$, and $A_{||} = 21172 \pm 1059$ [MHz]. These findings lead to a significant reduction of the theoretical uncertainties for ${\cal{P,T}}$-odd interaction constants but not to stronger constraints on the electron electric dipole moment, $d_e$, or the nucleon-electron scalar-pseudoscalar coupling constant, $C_S$.