First Observation of P-odd γ Asymmetry in Polarized Neutron Capture on Hydrogen.
Phys Rev Lett
; 121(24): 242002, 2018 Dec 14.
Article
em En
| MEDLINE
| ID: mdl-30608729
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}â^{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}â^{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.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Revista:
Phys Rev Lett
Ano de publicação:
2018
Tipo de documento:
Article
País de afiliação:
Estados Unidos