Abstract
Nuclear Schiff moments (NSMs) are sensitive probes for physics beyond the Standard Model of particle physics, signaling violations of time-reversal and parity-inversion symmetries in atomic nuclei. In this Letter, we report the first-ever calculation of a NSM in a nuclear ab initio framework, employing the no-core shell model to study the fluorine isotope ¹⁹F. We further perform quantum-chemistry calculations to evaluate the sensitivity of the hafnium monofluoride cation, HfF⁺, to the NSM of ¹⁹F. Combined with recent high-precision measurements of the molecular electric dipole moment of HfF⁺, our results enable the first experimental bound on the NSM of ¹⁹F. Although the resulting bounds on the pion-nucleon-nucleon (πNN) coupling constants are not yet the most stringent, this work establishes the foundation for constraining πNN interactions using nuclear ab initio methods.