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

(NPDGamma Collaboration)

doi:10.1103/PhysRevLett.121.242002

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

(NPDGamma Collaboration)

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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.

Original language	English
Article number	242002
Journal	Physical Review Letters
Volume	121
Issue number	24
DOIs	https://doi.org/10.1103/PhysRevLett.121.242002
State	Published - Dec 13 2018

Funding

We gratefully acknowledge the support of the U.S. Department of Energy Office of Nuclear Physics through Grants No. DE-AC52-06NA25396, No. DE-FG02-03ER41258, No. DE-SC0014622, No. DE-AC-02-06CH11357, No. DE-AC05-00OR22725, and No. DE-SC0008107, the U.S. National Science Foundation through Grants No. PHY-1306547, No. PHY-1306942, No. PHY-1614545, No. PHY-0855584, No. PHY-0855610, No. PHY-1205833, No. PHY-1506021, No. PHY-1205393, and No. PHY-0855694, PAPIIT-UNAM Grants No. IN110410, No. IN11193, and No. IG1011016, CONACYT Grant No. 080444, the Natural Sciences and Engineering Research Council of Canada (NSERC) Grants No. SAPPJ/341298 and No. SAPEQ/375650, and the Canadian Foundation for Innovation (CFI). This research used resources of the Spallation Neutron Source of Oak Ridge National Laboratory, a DOE Office of Science User Facility. J. F., R. C. G., J. M., W. M. S., and Z. T. acknowledge support from the Indiana University Center for Spacetime Symmetries. S. S. acknowledges support from the German Academic Exchange Service (DAAD).

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10.1103/PhysRevLett.121.242002

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@article{0540d706aa114cd4b1e7c04269d6d09a,

title = "First Observation of P -odd γ Asymmetry in Polarized Neutron Capture on Hydrogen",

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.",

author = "{(NPDGamma Collaboration)} and D. Blyth and J. Fry and N. Fomin and R. Alarcon and L. Alonzi and E. Askanazi and S. Bae{\ss}ler and S. Balascuta and L. Barr{\'o}n-Palos and A. Barzilov and Bowman, {J. D.} and N. Birge and Calarco, {J. R.} and Chupp, {T. E.} and V. Cianciolo and Coppola, {C. E.} and Crawford, {C. B.} and K. Craycraft and D. Evans and C. Fieseler and E. Frle{\v Z} and I. Garishvili and Gericke, {M. T.W.} and Gillis, {R. C.} and Grammer, {K. B.} and Greene, {G. L.} and J. Hall and J. Hamblen and C. Hayes and Iverson, {E. B.} and Kabir, {M. L.} and S. Kucuker and B. Lauss and R. Mahurin and M. McCrea and M. Maldonado-Vel{\'a}zquez and Y. Masuda and J. Mei and R. Milburn and Mueller, {P. E.} and M. Musgrave and H. Nann and I. Novikov and D. Parsons and Penttil{\"a}, {S. I.} and D. Po{\v c}ani{\'c} and A. Ramirez-Morales and M. Root and A. Salas-Bacci and S. Santra",

note = "Publisher Copyright: {\textcopyright} 2018 American Physical Society.",

year = "2018",

month = dec,

day = "13",

doi = "10.1103/PhysRevLett.121.242002",

language = "English",

volume = "121",

journal = "Physical Review Letters",

issn = "0031-9007",

publisher = "American Physical Society",

number = "24",

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TY - JOUR

T1 - First Observation of P -odd γ Asymmetry in Polarized Neutron Capture on Hydrogen

AU - (NPDGamma Collaboration)

AU - Blyth, D.

AU - Fry, J.

AU - Fomin, N.

AU - Alarcon, R.

AU - Alonzi, L.

AU - Askanazi, E.

AU - Baeßler, S.

AU - Balascuta, S.

AU - Barrón-Palos, L.

AU - Barzilov, A.

AU - Bowman, J. D.

AU - Birge, N.

AU - Calarco, J. R.

AU - Chupp, T. E.

AU - Cianciolo, V.

AU - Coppola, C. E.

AU - Crawford, C. B.

AU - Craycraft, K.

AU - Evans, D.

AU - Fieseler, C.

AU - FrleŽ, E.

AU - Garishvili, I.

AU - Gericke, M. T.W.

AU - Gillis, R. C.

AU - Grammer, K. B.

AU - Greene, G. L.

AU - Hall, J.

AU - Hamblen, J.

AU - Hayes, C.

AU - Iverson, E. B.

AU - Kabir, M. L.

AU - Kucuker, S.

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.

AU - Penttilä, S. I.

AU - Počanić, D.

AU - Ramirez-Morales, A.

AU - Root, M.

AU - Salas-Bacci, A.

AU - Santra, S.

PY - 2018/12/13

Y1 - 2018/12/13

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.

UR - http://www.scopus.com/inward/record.url?scp=85059135486&partnerID=8YFLogxK

U2 - 10.1103/PhysRevLett.121.242002

DO - 10.1103/PhysRevLett.121.242002

M3 - Article

C2 - 30608729

AN - SCOPUS:85059135486

SN - 0031-9007

VL - 121

JO - Physical Review Letters

JF - Physical Review Letters

IS - 24

M1 - 242002

ER -

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

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