First Observation of P -odd γ Asymmetry in Polarized Neutron Capture on Hydrogen

(NPDGamma Collaboration)

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

We report the first observation of the parity-violating gamma-ray asymmetry Aγnp in neutron-proton capture using polarized cold neutrons incident on a liquid parahydrogen target at the Spallation Neutron Source at Oak Ridge National Laboratory. Aγnp isolates the ΔI=1, S31→P31 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 Aγnp=[-3.0±1.4(stat)±0.2(syst)]×10-8, which implies a DDH weak πNN coupling of hπ1=[2.6±1.2(stat)±0.2(syst)]×10-7 and a pionless EFT constant of CS31→P31/C0=[-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.

Original languageEnglish (US)
Article number242002
JournalPhysical Review Letters
Volume121
Issue number24
DOIs
StatePublished - Dec 13 2018

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asymmetry
neutrons
cold neutrons
nucleon-nucleon interactions
spallation
hydrogen
neutron sources
ridges
parity
pions
mesons
gamma rays
protons
liquids

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

First Observation of P -odd γ Asymmetry in Polarized Neutron Capture on Hydrogen. / (NPDGamma Collaboration).

In: Physical Review Letters, Vol. 121, No. 24, 242002, 13.12.2018.

Research output: Contribution to journalArticle

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abstract = "We report the first observation of the parity-violating gamma-ray asymmetry Aγnp in neutron-proton capture using polarized cold neutrons incident on a liquid parahydrogen target at the Spallation Neutron Source at Oak Ridge National Laboratory. Aγnp isolates the ΔI=1, S31→P31 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 Aγnp=[-3.0±1.4(stat)±0.2(syst)]×10-8, which implies a DDH weak πNN coupling of hπ1=[2.6±1.2(stat)±0.2(syst)]×10-7 and a pionless EFT constant of CS31→P31/C0=[-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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AU - Blyth, D.

AU - Fry, J.

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AU - Alarcon, Ricardo

AU - Alonzi, L.

AU - Askanazi, E.

AU - Baeßler, S.

AU - Balascuta, S.

AU - Barrón-Palos, L.

AU - Barzilov, A.

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AU - Gericke, M. T.W.

AU - Gillis, R. C.

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AU - Hamblen, J.

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AU - Iverson, E. B.

AU - Kabir, M. L.

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AU - Lauss, B.

AU - Mahurin, R.

AU - McCrea, M.

AU - Maldonado-Velázquez, M.

AU - Masuda, Y.

AU - Mei, J.

AU - Milburn, R.

AU - Mueller, P. E.

AU - Musgrave, M.

AU - Nann, H.

AU - Novikov, I.

AU - Parsons, D.

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AU - Počanić, D.

AU - Ramirez-Morales, A.

AU - Root, M.

AU - Salas-Bacci, A.

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N2 - We report the first observation of the parity-violating gamma-ray asymmetry Aγnp in neutron-proton capture using polarized cold neutrons incident on a liquid parahydrogen target at the Spallation Neutron Source at Oak Ridge National Laboratory. Aγnp isolates the ΔI=1, S31→P31 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 Aγnp=[-3.0±1.4(stat)±0.2(syst)]×10-8, which implies a DDH weak πNN coupling of hπ1=[2.6±1.2(stat)±0.2(syst)]×10-7 and a pionless EFT constant of CS31→P31/C0=[-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.

AB - We report the first observation of the parity-violating gamma-ray asymmetry Aγnp in neutron-proton capture using polarized cold neutrons incident on a liquid parahydrogen target at the Spallation Neutron Source at Oak Ridge National Laboratory. Aγnp isolates the ΔI=1, S31→P31 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 Aγnp=[-3.0±1.4(stat)±0.2(syst)]×10-8, which implies a DDH weak πNN coupling of hπ1=[2.6±1.2(stat)±0.2(syst)]×10-7 and a pionless EFT constant of CS31→P31/C0=[-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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