New constraints on axion-mediated P , T -violating interaction from electric dipole moments of diamagnetic atoms

Abstract

The exchange of an axion-like particle between atomic electrons and the nucleus may induce electric dipole moments (EDMs) of atoms and molecules. This interaction is described by a parity- and time-reversal-invariance-violating potential which depends on the product of a scalar $g^s$ and a pseudoscalar $g^p$ coupling constant. We consider the interaction with the specific combination of these constants, $g_e^s g_N^p$, which gives significant contributions to the EDMs of diamagnetic atoms. In this paper, we calculate these contributions to the EDMs of $^{199}$Hg, $^{129}$Xe, $^{211}$Rn and $^{225}$Ra for a wide range of axion masses. Comparing these results with recent experimental EDM measurements, we place new constraints on $g_e^s g_N^p$. The most stringent atomic EDM limits come from $^{199}$Hg and improve on existing laboratory limits from other experiments for axion masses exceeding $10^{-2}$ eV.