Abstract
Experiments with paramagnetic ground or metastable excited states of molecules (ThO, HfF+, YbF, YbOH, BaF, PbO, etc.) provide strong constraints on the electron electric dipole moment (EDM) and the coupling constant CSP of contact semileptonic interaction. We compute new contributions to CSP arising from the nucleon EDMs due to the combined electric and magnetic electron-nucleon interaction. This allows us to improve limits from the experiments with paramagnetic molecules on the CP-violating parameters, such as the proton EDM, |dp| < 1.1 × 10−23e·cm, the QCD vacuum angle, left|overline{theta}right| < 1.4 × 10−8, as well as the quark chromo-EDMs and the π-meson-nucleon couplings. Our results may also be used to search for the axion dark matter which produces oscillating overline{theta} .
Highlights
In conclusions of this subsection we discuss the accuracy of our estimates of matrix elements and corresponding energies presented in tables 3 and 4
Using the data from table 4, we find this quantity for 232Th, B0 = 14.8μ0, and for 172Yb, B0 = 14.6μ0
We conclude that the errors in determining values of nuclear matrix elements and corresponding energies of spin-flip M1 transitions are under 50% for all nuclei. This level of accuracy is acceptable for the goals of this work, a better accuracy may be achieved with the use of more sophisticated nuclear models
Summary
The CP -odd interaction (1.1) between a valence electron and the nucleus is described by the Hamiltonian [45]. We will estimate the matrix element p1/2| Hcont |s1/2 for heavy atoms. In subsequent sections, this matrix element will be compared with those of CP -odd operators originating from nucleon EDMs. For an atom with a point-like nucleus, the s1/2 and p1/2 valence electron wave functions have simple analytic expressions, see eqs. For an extended nucleus model with constant charge density, it is sufficient to consider a simple continuation of the wave functions (B.3) to the region inside the nucleus as. With the wave functions (2.3), the matrix element of the operator (2.1) reads p1/2| Hcont |s1/2. For heavy nuclei, this matrix element is significantly enhanced due to the factor AZ2γ+1. Since we will compare eq (2.4) with the contribution from nucleon EDMs, which is not enhanced that strongly, it appears that for the ratio of the effects (which is the contribution from nucleon EDMs to the effective constant CSP ) lighter nuclei may have bigger CSP than heavy ones
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