P,T-odd eEDM enhancement factors in Yb-containing diatomic molecules

AUCAR, IGNACIO AGUSTÍN

Warsaw

Conferencia; 13th International Meeting on Atomic and Molecular Physics and Chemistry; 2024

University of Warsaw

The Standard Model of Particle Physics (SM) describes matter, radiation, and their interactions in terms of elementary particles. Although it provides very accurate predictions for many known physical phenomena, there are still open questions that this model cannot answer. Between them is the origin of the matter-antimatter imbalance and the nature of dark matter. This limitation is enough to think that new physics must exist beyond SM. One way to search for such physics is to investigate new sources of violation of the combined charge conjugation (C) and parity (P) symmetries, as they are crucial to explain the matter-antimatter asymmetry. Permanent electric dipole moments (EDMs) induce interactions that violate the CP symmetry, and even though the SM predicts some contributions to them, they are not sufficient to explain the matter-antimatter asymmetry. According to the SM, paramagnetic diatomic molecules with spin-zero nuclei are expected to be especially sensitive to two sources of CP violation, i.e., interactions between electron EDMs (eEDMs) and electromagnetic fields, and parity and time-reversal (T) violating scalar-pseudoscalar nucleon-electron (S-PS-ne) neutral-current interactions. Since their effects are far from experimental limits, a non-zero detection of CP violation would be evidence of new physics.In this work, we present a study of SM-based CP-odd interactions on molecules. To investigate the eEDM and S-PS-ne interactions through precision experiments on molecular systems, two P,T-odd enhancement factors (W_d and W_s) must be predicted using accurate ab-initio electronic structure computations, as they cannot be measured. Furthermore, choosing the right candidate system has a significant impact on the sensitivity of these effects, since the enhancement factors depend on the molecular electronic structure. We have predicted the values of W_d and W_s for three paramagnetic molecules, YbCu, YbAg and YbAu, with a significant level of theoretical precision. Although no experiments have been done with these molecules so far, very precise calculations of potential energy curves, quadrupole moments, and static electric dipole polarizabilities have recently been performed, paving the way to propose these molecules for the search for new physics. We provide recommended values of the enhancement factors, calculated using the four-component Dirac-Coulomb Hamiltonian to deal with relativistic effects and employing the Fock-space coupled-cluster method to include electron correlation effects with high precision. Furthermore, following an approach that has been validated in previous studies, we carried out a comprehensive uncertainty analysis in order to assign reliable error bars to the obtained results.