| Literature DB >> 30608729 |
D Blyth1,2, J Fry3,4, N Fomin5,6, R Alarcon1, L Alonzi3, E Askanazi3, S Baeßler3,7, S Balascuta1,8, L Barrón-Palos9, A Barzilov10, J D Bowman7, N Birge5, J R Calarco11, T E Chupp12, V Cianciolo7, C E Coppola5, C B Crawford13, K Craycraft5,13, D Evans3,4, C Fieseler13, E Frlež3, I Garishvili5,7, M T W Gericke14, R C Gillis4,7, K B Grammer5,7, G L Greene5,7, J Hall3, J Hamblen15, C Hayes5,16, E B Iverson7, M L Kabir13,17, S Kucuker5,18, B Lauss19, R Mahurin20, M McCrea13,14, M Maldonado-Velázquez9, Y Masuda21, J Mei4, R Milburn13, P E Mueller7, M Musgrave5,22, H Nann4, I Novikov23, D Parsons15, S I Penttilä7, D Počanić3, A Ramirez-Morales9, M Root3, A Salas-Bacci3, S Santra24, S Schröder3,25, E Scott5, P-N Seo3,26, E I Sharapov27, F Simmons13, W M Snow4, A Sprow13, J Stewart15, E Tang6,13, Z Tang4,6, X Tong7, D J Turkoglu28, R Whitehead5, W S Wilburn6.
Abstract
We report the first observation of the parity-violating gamma-ray asymmetry A_{γ}^{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_{γ}^{np} isolates the ΔI=1, ^{3}S_{1}→^{3}P_{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. We measured A_{γ}^{np}=[-3.0±1.4(stat)±0.2(syst)]×10^{-8}, which implies a DDH weak πNN coupling of h_{π}^{1}=[2.6±1.2(stat)±0.2(syst)]×10^{-7} and a pionless EFT constant of C^{^{3}S_{1}→^{3}P_{1}}/C_{0}=[-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.Entities:
Year: 2018 PMID： 30608729 DOI： 10.1103/PhysRevLett.121.242002
Source DB: PubMed Journal: Phys Rev Lett ISSN： 0031-9007 Impact factor: 9.161