Reappraisal of P, T-odd parameters from the improved calculation of electric dipole moment of 225Ra atom

Abstract

By employing the recently developed relativistic normal coupled-cluster theory, we obtained the electric dipole moment (EDM) of 225Ra due to nuclear Schiff moment (NSM) and tensor–pseudotensor (T–PT) electron–nucleus (e–N) interaction as −6.3(5) × 10−17 S |e| cm/(|e| fm3) and −13(1) × 10−20 CT⟨σN⟩ |e| cm, respectively, for the NSM S, T–PT coupling coefficient CT and nuclear Pauli spinor σN. This is corroborated by analyzing the dipole polarizability value of 225Ra, which is obtained as 257(8) . Our EDM results, in combination with the measurement (2015 Phys. Rev. Lett. 114 233002), are about 8% and 28% improvements over the limits that were reported using the relativistic coupled-cluster theory for the NSM and T–PT e–N coupling coefficient, respectively. Further combining with the nuclear calculations, we infer limits on the EDM of neutron dn < 1.15 × 10−23 |e| cm, the EDM of proton dp < 1.1 × 10−22 |e| cm, the quantum chromodynamics parameter and the combined up- and down-quark chromo-EDMs . Though these bounds are not competitive at present with the current-best limits acquired from 199Hg atom, they can be bettered when the measurement of EDM in 225Ra improves by four orders.