Physical Sciences and Mathematics Commons^™

Search For Dark Matter Decay Of The Free Neutron From The Ucna Experiment: N → Χ + E+E−, X. Sun, E. Adamek, B. Allgeier, M. Blatnik, T. J. Bowles, L. J. Broussard, M. A. -P. Brown, R. Carr, S. Clayton, C. Cude-Woods, S. Currie, E. B. Dees, X. Ding, B. W. Filippone, A. García, P. Geltenbort, S. Hasan, K. P. Hickerson, J. Hoagland, R. Hong, G. E. Hogan, A. T. Holley, T. M. Ito, A. Knecht, C. -Y. Liu, J. Liu, M. Makela, R. Mammei, J. W. Martin, D. Melconian, Subash C. Nepal, Bradley R. Plaster

Physics and Astronomy Faculty Publications

It has been proposed recently that a previously unobserved neutron decay branch to a dark matter particle (χ) could account for the discrepancy in the neutron lifetime observed in experiments that use two different measurement techniques. One of the possible final states discussed includes a single χ along with an e⁺e⁻ pair. We use data from the UCNA (Ultracold Neutron Asymmetry) experiment to set limits on this decay channel. Coincident electron-like events are detected with ∼4π acceptance using a pair of detectors that observe a volume of stored ultracold neutrons. The summed kinetic energy (E_{e …}

New Result For The Neutron Β-Asymmetry Parameter A0 From Ucna, M. A.-P. Brown, E. B. Dees, E. Adamek, B. Allgeier, M. Blatnik, T. J. Bowles, L. J. Broussard, R. Carr, S. Clayton, C. Cude-Woods, S. Currie, X. Ding, B. W. Filippone, A. García, P. Geltenbort, S. Hasan, K. P. Hickerson, J. Hoagland, R. Hong, G. E. Hogan, A. T. Holley, T. M. Ito, A. Knecht, C. -Y. Liu, J. Liu, M. Makela, J. W. Martin, D. Melconian, M. P. Mendenhall, S. D. Moore, Subash C. Nepal, N. Nouri, Bradley R. Plaster

Physics and Astronomy Faculty Publications

Background: The neutron β-decay asymmetry parameter A₀ defines the angular correlation between the spin of the neutron and the momentum of the emitted electron. Values for A₀ permit an extraction of the ratio of the weak axial-vector to vector coupling constants, λ ≡ g_A/g_V, which under assumption of the conserved vector current hypothesis (g_V = 1) determines g_A. Precise values for g_A are important as a benchmark for lattice QCD calculations and as a test of the standard model.

Purpose: The UCNA experiment, carried out at the …