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. This was sought using a slow neutron polarimeter that passed transversely polarized slow neutrons by unpolarized slabs of material arranged so that interactions would tilt the plane of polarization and develop a component along the neutron momentum. The result for the rotation angle, ϕ′=[2.8±4.6(stat.)±4.0(sys.)]×10−5 rad/m is consistent with zero. This result improves the upper bounds on the neutron-matter coupling g2A by about three orders of magnitude for force ranges in the mm– μm regime

Neutron Decay Correlations in the Nab Experiment

The Nab experiment will measure the correlation a between the momenta of the beta particle and antineutrino in neutron decay as well as the Fierz term b which distorts the beta spectrum

First Observation of \u3cem\u3eP\u3c/em\u3e-Odd γ Asymmetry in Polarized Neutron Capture on Hydrogen

We report the first observation of the parity-violating gamma-ray asymmetry Anpγ in neutron-proton capture using polarized cold neutrons incident on a liquid parahydrogen target at the Spallation Neutron Source at Oak Ridge National Laboratory. Anpγ isolates the ΔI = 1, 3S1 → 3P1 component of the weak nucleon-nucleon interaction, which is dominated by pion exchange and can be directly related to a single coupling constant in either the DDH meson exchange model or pionless effective field theory. We measured Anpγ = [−3.0 ± 1.4(stat )± 0.2(syst)] × 10−8, which implies a DDH weak πNN coupling of h1π = [2.6 ± 1.2(stat) ± 0.2(syst)] × 10−7 and a pionless EFT constant of C3S1 → 3P1/C0 = [−7.4 ± 3.5(stat) ± 0.5(syst)] × 10−11  MeV−1. We describe the experiment, data analysis, systematic uncertainties, and implications of the result

First Observation of P-odd gamma Asymmetry in Polarized Neutron Capture on Hydrogen

We report the first observation of the parity-violating gamma-ray asymmetry A(gamma)(np) in neutron-proton capture using polarized cold neutrons incident on a liquid parahydrogen target at the Spallation Neutron Source at Oak Ridge National Laboratory. A(gamma)(np) isolates the Delta I = 1, S-3(1)-\u3e P-3(1) component of the weak nucleon-nucleon interaction, which is dominated by pion exchange and can be directly related to a single coupling constant in either the DDH meson exchange model or pionless effective field theory… See full text for full abstract