First observation of p-odd γ asymmetry in polarized neutron capture on hydrogen
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PhysRevLett.121.242002.pdf
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328.84 KB
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Author(s)
Musgrave, Matthew
NPDGamma Collaboration
Date Issued
December 2018
Journal
Physical review letters
Publisher
American Physical Society
Citation
NPDGamma Collaboration (Blyth, D., et al.), "First observation of p-odd γ asymmetry in polarized neutron capture on hydrogen." Physical review letters 121 (Dec. 2018): no. 242002 doi 10.1103/PhysRevLett.121.242002 ©2018 Author(s)
Version
Final published version
Abstract
We report the first observation of the parity-violating gamma-ray asymmetry A[subscript γ under superscript 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[subscript γ under superscript np] isolates the ΔI=1, ³S[subscript 1]→³P[subscript 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[subscript γ under superscript np]=[-3.0±1.4(stat)±0.2(syst)]×10-⁸, which implies a DDH weak πNN coupling of h[subscript π under superscript 1]=[2.6±1.2(stat)±0.2(syst)]×10-⁷ and a pionless EFT constant of [physics equation; see resource]. We describe the experiment, data analysis, systematic uncertainties, and implications of the result. ©2018
MIT Department
Massachusetts Institute of Technology. Laboratory for Nuclear Science
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DOI of Published Version
https://doi.org/10.1103/PhysRevLett.121.242002
