A Search for Possible Long Range Spin Dependent Interactions of the Neutron From Exotic Vector Boson Exchange.

We present a search for possible spin dependent interactions of the neutron with matter through exchange of spin 1 bosons with axial vector couplings as envisioned in possible extensions of the Standard Model. We sought this interaction using a slow neutron polarimeter that passed transversely polarized slow neutrons by unpolarized slabs of material arranged so that this interaction would tilt the plane of polarization and develop a component along the neutron momentum. The result for the rotation angle, $\phi'_{V_5} = [1.4\pm\,2.3(stat.)\pm\,2.8(sys.)]\times 10^{-5}~\mbox{rad}$ is consistent with zero. This result improves the upper bounds on the neutron-matter coupling $g_{A}^{2}$ from such an interaction by about 3 orders of magnitude for force ranges in the mm-$\mu$m regime.