Extensions of the Standard Model of Particle Physics usually predict new particles and therefore also new interactions. One possible spin-dependent interaction between a nucleon and a new vector boson (spin 1) can be tested using a polarized probe and an unpolarized sample in close proximity. The axial coupling of the sample would create a pseudo-magnetic field that can be precisely measured using Ramsey’s technique of separated oscillatory fields. The current best limits on this interaction, for an interaction length of less than 8 mm, were established using a polarized neutron beam and a copper sample [Piegsa & Pignol, Phys. Rev. Lett. 108, 181801 (2012)]. In our group, we plan to improve this limit with neutrons, but also extend this search to the axial coupling to protons, using NMR techniques with protons in flowing water. A demonstration of this technique was published recently [Schulthess et al., J. Magn. Res. 353, 107496 (2023)].
