Paper

New result for the neutron \\(\\beta\\)-asymmetry parameter \\(A_0\\) from UCNA

Knecht, A, Broussard, L J, Nouri, N, Blatnik, M, Swift, G, Morris, C L, Young, A R, Cude-Woods, C, Hasan, S, Clayton, S, Pattie, R W, Ding, X, Holley, A T, Dees, E B, Plaster, B, Sjue, S, Carr, R, Moore, S D, Brown, M A -P, Seestrom, S J, Hickerson, K P, Wrede, C, VornDick, B, Slutsky, S, Vogelaar, R B, Rios, R, Tatar, E, Sondheim, W, Hoagland, J, Adamek, E, Phillips, D G, Hogan, G E, Picker, R, Hong, R, C -Y Liu, Ramsey, J C, Perez-Galvan, A, Zeck, B A, Allgeier, B, Garcia, A, Saunders, A, Salvat, D J, Wang, Z, Nepal, S, Currie, S, Filippone, B W, Geltenbort, P, Ito, T M, Jr, Melconian, D, Makela, M, Martin, J W, Bowles, T J, Pitt, M L, Liu, J, Wexler, J, Mendenhall, M P, Swank, C, Womack, T, Sun, X

2018

Overview

The neutron \\(\\beta\\)-decay asymmetry parameter \\(A_0\\) defines the correlation between the spin of the neutron and the momentum of the emitted electron, which determines \\(\\lambda=\\frac{g_{A}}{g_{V}}\\), the ratio of the axial-vector to vector weak coupling constants. The UCNA Experiment, located at the Ultracold Neutron facility at the Los Alamos Neutron Science Center, is the first to measure such a correlation coefficient using ultracold neutrons (UCN). Following improvements to the systematic uncertainties and increased statistics, we report the new result \\(A_0 = -0.12054(44)_{\\mathrm{stat}}(68)_{\\mathrm{syst}}\\) which yields \\(\\lambda\\equiv \\frac{g_{A}}{g_{V}}=-1.2783(22)\\). Combination with the previous UCNA result and accounting for correlated systematic uncertainties produces \\(A_0=-0.12015(34)_{\\mathrm{stat}}(63)_{\\mathrm{syst}}\\) and \\(\\lambda\\equiv \\frac{g_{A}}{g_{V}}=-1.2772(20)\\).

• Publisher: Cornell University Library, arXiv.org
• Subject: Asymmetry / Beta decay / Correlation analysis / Correlation coefficients / Neutrons / Parameters / Uncertainty