Nuclear Schiff Moment of the Fluorine Isotope ^{19}F

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 ^{19}F. We further perform quantum-chemistry calculations to evaluate the sensitivity of the hafnium monofluoride cation, HfF^{+}, to the NSM of ^{19}F. Combined with recent high-precision measurements of the molecular electric dipole moment of HfF^{+} [Roussy et al., An improved bound on the electron's electric dipole moment, Science 381, 46 (2023).SCIEAS0036-807510.1126/science.adg4084], our results enable the first experimental bound on the NSM of ^{19}F. Although the resulting bounds on the pion-nucleon-nucleon (πNN) coupling constants are not yet the most stringent, this Letter establishes the foundation for constraining πNN interactions using nuclear ab initio methods.