Axion-mediated electron-nucleus and electron-electron interactions in barium monofluoride molecule

Abstract

The effects induced by the time-reversal ($\mathcal{T}$) and spatial parity ($\mathcal{P}$) violating electron-nucleus and electron-electron interactions mediated by the axion-like particles (ALPs) in the BaF molecule were estimated. Molecular parameters characterizing these interactions were calculated across a wide range of ALP masses. In case of the electron-nuclear interaction, the effect of the extended nucleus was studied and shown to be significant for heavy ALPs. Based on the calculated molecular parameters, we obtained a link between the $\mathcal{T}$,$\mathcal{P}$-violating energy shift which can be measured in the ongoing experiment designed to search for the electron electric dipole moment using the BaF molecule [A. Boeschoten et al., arXiv:2303.06402 (2023)] and the products of coupling constants of the ALP-electron or ALP-electron and ALP-nucleus interactions.