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Reinhard PG, Roca-Maza X, Nazarewicz W. Combined Theoretical Analysis of the Parity-Violating Asymmetry for ^{48}Ca and ^{208}Pb. PHYSICAL REVIEW LETTERS 2022; 129:232501. [PMID: 36563216 DOI: 10.1103/physrevlett.129.232501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 08/02/2022] [Accepted: 11/18/2022] [Indexed: 06/17/2023]
Abstract
The recent experimental determination of the parity violating asymmetry A_{PV} in ^{48}Ca and ^{208}Pb at Jefferson Lab is important for our understanding on how neutrons and protons arrange themselves inside the atomic nucleus. To better understand the impact of these measurements, we present a rigorous theoretical investigation of A_{PV} in ^{48}Ca and ^{208}Pb and assess the associated uncertainties. We complement our study by inspecting the static electric dipole polarizability in these nuclei. The analysis is carried out within nuclear energy density functional theory with quantified input. We conclude that the simultaneous accurate description of A_{PV} in ^{48}Ca and ^{208}Pb cannot be achieved by our models that accommodate a pool of global nuclear properties, such as masses and charge radii, throughout the nuclear chart, and describe-within one standard deviation-the experimental dipole polarizabilities α_{D} in these nuclei.
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Affiliation(s)
| | - Xavier Roca-Maza
- Dipartimento di Fisica "Aldo Pontremoli," Università degli Studi di Milano, 20133 Milano, Italy and INFN, Sezione di Milano, 20133 Milano, Italy
| | - Witold Nazarewicz
- Facility for Rare Isotope Beams and Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
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2
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Reinhard PG, Roca-Maza X, Nazarewicz W. Information Content of the Parity-Violating Asymmetry in ^{208}Pb. PHYSICAL REVIEW LETTERS 2021; 127:232501. [PMID: 34936797 DOI: 10.1103/physrevlett.127.232501] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 10/27/2021] [Indexed: 06/14/2023]
Abstract
The parity-violating asymmetry A_{PV} in ^{208}Pb, recently measured by the PREX-2 Collaboration, is studied using modern relativistic (covariant) and nonrelativistic energy density functionals. We first assess the theoretical uncertainty on A_{PV} which is intrinsic to the adopted approach. To this end, we use quantified functionals that are able to accommodate our previous knowledge on nuclear observables such as binding energies, charge radii, and the dipole polarizability α_{D} of ^{208}Pb. We then add the quantified value of A_{PV} together with α_{D} to our calibration dataset to optimize new functionals. Based on these results, we predict a neutron skin thickness in ^{208}Pb r_{skin}=0.19±0.02 fm and the symmetry-energy slope L=54±8 MeV. These values are consistent with other estimates based on astrophysical data and are significantly lower than those recently reported using a particular set of relativistic energy density functionals. We also make a prediction for the A_{PV} value in ^{48}Ca that will be soon available from the CREX measurement.
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Affiliation(s)
| | - Xavier Roca-Maza
- Dipartimento di Fisica "Aldo Pontremoli," Università degli Studi di Milano, 20133 Milano, Italy and INFN, Sezione di Milano, 20133 Milano, Italy
| | - Witold Nazarewicz
- Facility for Rare Isotope Beams and Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
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3
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Precision measurement of the weak charge of the proton. Nature 2018; 557:207-211. [DOI: 10.1038/s41586-018-0096-0] [Citation(s) in RCA: 92] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Accepted: 04/05/2018] [Indexed: 11/09/2022]
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Androic D, Armstrong D, Asaturyan A, Averett T, Balewski J, Bartlett K, Beaufait J, Beminiwattha R, Benesch J, Benmokhtar F, Birchall J, Carlini R, Cates G, Cornejo J, Covrig S, Dalton M, Davis C, Deconinck W, Diefenbach J, Dowd J, Dunne J, Dutta D, Duvall W, Elaasar M, Falk W, Finn J, Forest T, Gal C, Gaskell D, Gericke M, Grames J, Gray V, Grimm K, Guo F, Hoskins J, Johnston K, Jones D, Jones M, Jones R, Kargiantoulakis M, King P, Korkmaz E, Kowalski S, Leacock J, Leckey J, Lee A, Lee J, Lee L, MacEwan S, Mack D, Magee J, Mahurin R, Mammei J, Martin J, McHugh M, Meekins D, Mei J, Michaels R, Micherdzinska A, Mkrtchyan A, Mkrtchyan H, Morgan N, Myers K, Narayan A, Ndukum L, Nelyubin V, Nuhait H, Nuruzzaman, van Oers W, Opper A, Page S, Pan J, Paschke K, Phillips S, Pitt M, Poelker M, Rajotte J, Ramsay W, Roche J, Sawatzky B, Seva T, Shabestari M, Silwal R, Simicevic N, Smith G, Solvignon P, Spayde D, Subedi A, Subedi R, Suleiman R, Tadevosyan V, Tobias W, Tvaskis V, Waidyawansa B, Wang P, Wells S, Wood S, Yang S, Young R, Zang P, Zhamkochyan S. Qweak: First Direct Measurement of the Proton’s Weak Charge. EPJ WEB OF CONFERENCES 2017. [DOI: 10.1051/epjconf/201713708005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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6
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Sufian RS, Yang YB, Alexandru A, Draper T, Liang J, Liu KF. Strange Quark Magnetic Moment of the Nucleon at the Physical Point. PHYSICAL REVIEW LETTERS 2017; 118:042001. [PMID: 28186787 DOI: 10.1103/physrevlett.118.042001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Indexed: 06/06/2023]
Abstract
We report a lattice QCD calculation of the strange quark contribution to the nucleon's magnetic moment and charge radius. This analysis presents the first direct determination of strange electromagnetic form factors including at the physical pion mass. We perform a model-independent extraction of the strange magnetic moment and the strange charge radius from the electromagnetic form factors in the momentum transfer range of 0.051 GeV^{2}≲Q^{2}≲1.31 GeV^{2}. The finite lattice spacing and finite volume corrections are included in a global fit with 24 valence quark masses on four lattices with different lattice spacings, different volumes, and four sea quark masses including one at the physical pion mass. We obtain the strange magnetic moment G_{M}^{s}(0)=-0.064(14)(09)μ_{N}. The four-sigma precision in statistics is achieved partly due to low-mode averaging of the quark loop and low-mode substitution to improve the statistics of the nucleon propagator. We also obtain the strange charge radius ⟨r_{s}^{2}⟩_{E}=-0.0043(16)(14) fm^{2}.
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Affiliation(s)
- Raza Sabbir Sufian
- Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506, USA
| | - Yi-Bo Yang
- Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506, USA
| | - Andrei Alexandru
- Department of Physics, The George Washington University, Washington, D.C. 20052, USA
| | - Terrence Draper
- Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506, USA
| | - Jian Liang
- Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506, USA
| | - Keh-Fei Liu
- Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506, USA
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7
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Wang P, Leinweber D, Thomas A. Pure sea-quark contributions to the magnetic form factors ofΣbaryons. Int J Clin Exp Med 2015. [DOI: 10.1103/physrevd.92.034508] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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8
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Shanahan PE, Horsley R, Nakamura Y, Pleiter D, Rakow PEL, Schierholz G, Stüben H, Thomas AW, Young RD, Zanotti JM. Determination of the strange nucleon form factors. PHYSICAL REVIEW LETTERS 2015; 114:091802. [PMID: 25793800 DOI: 10.1103/physrevlett.114.091802] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Indexed: 06/04/2023]
Abstract
The strange contribution to the electric and magnetic form factors of the nucleon is determined at a range of discrete values of Q^{2} up to 1.4 GeV^{2}. This is done by combining a recent analysis of lattice QCD results for the electromagnetic form factors of the octet baryons with experimental determinations of those quantities. The most precise result is a small negative value for the strange magnetic moment: G_{M}^{s}(Q^{2}=0)=-0.07±0.03μ_{N}. At larger values of Q^{2} both the electric and magnetic form factors are consistent with zero to within 2 standard deviations.
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Affiliation(s)
- P E Shanahan
- ARC Centre of Excellence in Particle Physics at the Terascale and CSSM, Department of Physics, University of Adelaide, Adelaide, SA 5005, Australia
| | - R Horsley
- School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3JZ, United Kingdom
| | - Y Nakamura
- RIKEN Advanced Institute for Computational Science, Kobe, Hyogo 650-0047, Japan
| | - D Pleiter
- JSC, Forschungzentrum Jülich, 52425 Jülich, Germany
- Institut für Theoretische Physik, Universität Regensburg, 93040 Regensburg, Germany
| | - P E L Rakow
- Theoretical Physics Division, Department of Mathematical Sciences, University of Liverpool, Liverpool L69 3BX, United Kingdom
| | - G Schierholz
- Deutsches Elektronen-Synchrotron DESY, 22603 Hamburg, Germany
| | - H Stüben
- Regionales Rechenzentrum, Universität Hamburg, 20146 Hamburg, Germany
| | - A W Thomas
- ARC Centre of Excellence in Particle Physics at the Terascale and CSSM, Department of Physics, University of Adelaide, Adelaide, SA 5005, Australia
| | - R D Young
- ARC Centre of Excellence in Particle Physics at the Terascale and CSSM, Department of Physics, University of Adelaide, Adelaide, SA 5005, Australia
| | - J M Zanotti
- ARC Centre of Excellence in Particle Physics at the Terascale and CSSM, Department of Physics, University of Adelaide, Adelaide, SA 5005, Australia
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Lovato A, Gandolfi S, Carlson J, Pieper SC, Schiavilla R. Neutral weak current two-body contributions in inclusive scattering from 12C. PHYSICAL REVIEW LETTERS 2014; 112:182502. [PMID: 24856692 DOI: 10.1103/physrevlett.112.182502] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Indexed: 06/03/2023]
Abstract
An ab initio calculation of the sum rules of the neutral weak response functions in 12C is reported, based on a realistic Hamiltonian, including two- and three-nucleon potentials, and on realistic currents, consisting of one- and two-body terms. We find that the sum rules of the response functions associated with the longitudinal and transverse components of the (spacelike) neutral current are largest and that a significant portion (≃30%) of the calculated strength is due to two-body terms. This fact may have implications for the MiniBooNE and other neutrino quasielastic scattering data on nuclei.
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Affiliation(s)
- A Lovato
- Argonne Leadership Computing Facility, Argonne National Laboratory, Argonne, Illinois 60439, USA and Physics Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - S Gandolfi
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - J Carlson
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Steven C Pieper
- Physics Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - R Schiavilla
- Theory Center, Jefferson Lab, Newport News, Virginia 23606, USA and Department of Physics, Old Dominion University, Norfolk, Virginia 23529, USA
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10
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Marinelli JR, Graeff CA. Nucleon size effects in the parity violating electron scattering asymmetry. EPJ WEB OF CONFERENCES 2014. [DOI: 10.1051/epjconf/20146602068] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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11
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Pate S, Trujillo D. Strangeness Vector and Axial-Vector Form Factors of the Nucleon. EPJ WEB OF CONFERENCES 2014. [DOI: 10.1051/epjconf/20146606018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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12
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Androic D, Armstrong D, Asaturyan A, Averett T, Balewski J, Beaufait J, Beminiwattha R, Benesch J, Benmokhtar F, Birchall J, Carlini R, Cates G, Cornejo J, Covrig S, Dalton M, Davis C, Deconinck W, Diefenbach J, Dowd J, Dunne J, Dutta D, Duvall W, Elaasar M, Falk W, Finn J, Forest T, Gaskell D, Gericke M, Grames J, Gray V, Grimm K, Guo F, Hoskins J, Johnston K, Jones D, Jones M, Jones R, Kargiantoulakis M, King P, Korkmaz E, Kowalski S, Leacock J, Leckey J, Lee A, Lee J, Lee L, MacEwan S, Mack D, Magee J, Mahurin R, Mammei J, Martin J, McHugh M, Meekins D, Mei J, Michaels R, Micherdzinska A, Mkrtchyan A, Mkrtchyan H, Morgan N, Myers K, Narayan A, Ndukum L, Nelyubin V, Nuruzzaman, van Oers W, Opper A, Page S, Pan J, Paschke K, Phillips S, Pitt M, Poelker M, Rajotte J, Ramsay W, Roche J, Sawatzky B, Seva T, Shabestari M, Silwal R, Simicevic N, Smith G, Solvignon P, Spayde D, Subedi A, Subedi R, Suleiman R, Tadevosyan V, Tobias W, Tvaskis V, Waidyawansa B, Wang P, Wells S, Wood S, Yang S, Young R, Zhamkochyan S. Early Results from the QweakExperiment. EPJ WEB OF CONFERENCES 2014. [DOI: 10.1051/epjconf/20146605002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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13
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Nuruzzaman. Qweak: First Direct Measurement of the Weak Charge of the Proton. EPJ WEB OF CONFERENCES 2014. [DOI: 10.1051/epjconf/20147100100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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14
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Androic D, Armstrong DS, Asaturyan A, Averett T, Balewski J, Beaufait J, Beminiwattha RS, Benesch J, Benmokhtar F, Birchall J, Carlini RD, Cates GD, Cornejo JC, Covrig S, Dalton MM, Davis CA, Deconinck W, Diefenbach J, Dowd JF, Dunne JA, Dutta D, Duvall WS, Elaasar M, Falk WR, Finn JM, Forest T, Gaskell D, Gericke MTW, Grames J, Gray VM, Grimm K, Guo F, Hoskins JR, Johnston K, Jones D, Jones M, Jones R, Kargiantoulakis M, King PM, Korkmaz E, Kowalski S, Leacock J, Leckey J, Lee AR, Lee JH, Lee L, MacEwan S, Mack D, Magee JA, Mahurin R, Mammei J, Martin JW, McHugh MJ, Meekins D, Mei J, Michaels R, Micherdzinska A, Mkrtchyan A, Mkrtchyan H, Morgan N, Myers KE, Narayan A, Ndukum LZ, Nelyubin V, van Oers WTH, Opper AK, Page SA, Pan J, Paschke KD, Phillips SK, Pitt ML, Poelker M, Rajotte JF, Ramsay WD, Roche J, Sawatzky B, Seva T, Shabestari MH, Silwal R, Simicevic N, Smith GR, Solvignon P, Spayde DT, Subedi A, Subedi R, Suleiman R, Tadevosyan V, Tobias WA, Tvaskis V, Waidyawansa B, Wang P, Wells SP, Wood SA, Yang S, Young RD, Zhamkochyan S. First determination of the weak charge of the proton. PHYSICAL REVIEW LETTERS 2013; 111:141803. [PMID: 24152148 DOI: 10.1103/physrevlett.111.141803] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Indexed: 06/02/2023]
Abstract
The Q(weak) experiment has measured the parity-violating asymmetry in ep elastic scattering at Q(2)=0.025(GeV/c)(2), employing 145 μA of 89% longitudinally polarized electrons on a 34.4 cm long liquid hydrogen target at Jefferson Lab. The results of the experiment's commissioning run, constituting approximately 4% of the data collected in the experiment, are reported here. From these initial results, the measured asymmetry is A(ep)=-279±35 (stat) ± 31 (syst) ppb, which is the smallest and most precise asymmetry ever measured in ep scattering. The small Q(2) of this experiment has made possible the first determination of the weak charge of the proton Q(W)(p) by incorporating earlier parity-violating electron scattering (PVES) data at higher Q(2) to constrain hadronic corrections. The value of Q(W)(p) obtained in this way is Q(W)(p)(PVES)=0.064±0.012, which is in good agreement with the standard model prediction of Q(W)(p)(SM)=0.0710±0.0007. When this result is further combined with the Cs atomic parity violation (APV) measurement, significant constraints on the weak charges of the up and down quarks can also be extracted. That PVES+APV analysis reveals the neutron's weak charge to be Q(W)(n)(PVES+APV)=-0.975±0.010.
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Affiliation(s)
- D Androic
- University of Zagreb, Zagreb HR-10002, Croatia
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Wang D, Pan K, Subedi R, Deng X, Ahmed Z, Allada K, Aniol KA, Armstrong DS, Arrington J, Bellini V, Beminiwattha R, Benesch J, Benmokhtar F, Camsonne A, Canan M, Cates GD, Chen JP, Chudakov E, Cisbani E, Dalton MM, de Jager CW, De Leo R, Deconinck W, Deur A, Dutta C, El Fassi L, Flay D, Franklin GB, Friend M, Frullani S, Garibaldi F, Giusa A, Glamazdin A, Golge S, Grimm K, Hafidi K, Hansen O, Higinbotham DW, Holmes R, Holmstrom T, Holt RJ, Huang J, Hyde CE, Jen CM, Jones D, Kang H, King P, Kowalski S, Kumar KS, Lee JH, LeRose JJ, Liyanage N, Long E, McNulty D, Margaziotis DJ, Meddi F, Meekins DG, Mercado L, Meziani ZE, Michaels R, Mihovilovic M, Muangma N, Myers KE, Nanda S, Narayan A, Nelyubin V, Oh Y, Parno D, Paschke KD, Phillips SK, Qian X, Qiang Y, Quinn B, Rakhman A, Reimer PE, Rider K, Riordan S, Roche J, Rubin J, Russo G, Saenboonruang K, Saha A, Sawatzky B, Shahinyan A, Silwal R, Sirca S, Souder PA, Suleiman R, Sulkosky V, Sutera CM, Tobias WA, Urciuoli GM, Waidyawansa B, Wojtsekhowski B, Ye L, Zhao B, Zheng X. Measurements of parity-violating asymmetries in electron-deuteron scattering in the nucleon resonance region. PHYSICAL REVIEW LETTERS 2013; 111:082501. [PMID: 24016222 DOI: 10.1103/physrevlett.111.082501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Indexed: 06/02/2023]
Abstract
We report on parity-violating asymmetries in the nucleon resonance region measured using inclusive inelastic scattering of 5-6 GeV longitudinally polarized electrons off an unpolarized deuterium target. These results are the first parity-violating asymmetry data in the resonance region beyond the Δ(1232). They provide a verification of quark-hadron duality-the equivalence of the quark- and hadron-based pictures of the nucleon-at the (10-15)% level in this electroweak observable, which is dominated by contributions from the nucleon electroweak γZ interference structure functions. In addition, the results provide constraints on nucleon resonance models relevant for calculating background corrections to elastic parity-violating electron scattering measurements.
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Affiliation(s)
- D Wang
- University of Virginia, Charlottesville, Virginia 22904, USA
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16
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Abrahamyan S, Ahmed Z, Albataineh H, Aniol K, Armstrong DS, Armstrong W, Averett T, Babineau B, Barbieri A, Bellini V, Beminiwattha R, Benesch J, Benmokhtar F, Bielarski T, Boeglin W, Camsonne A, Canan M, Carter P, Cates GD, Chen C, Chen JP, Hen O, Cusanno F, Dalton MM, De Leo R, de Jager K, Deconinck W, Decowski P, Deng X, Deur A, Dutta D, Etile A, Flay D, Franklin GB, Friend M, Frullani S, Fuchey E, Garibaldi F, Gasser E, Gilman R, Giusa A, Glamazdin A, Gomez J, Grames J, Gu C, Hansen O, Hansknecht J, Higinbotham DW, Holmes RS, Holmstrom T, Horowitz CJ, Hoskins J, Huang J, Hyde CE, Itard F, Jen CM, Jensen E, Jin G, Johnston S, Kelleher A, Kliakhandler K, King PM, Kowalski S, Kumar KS, Leacock J, Leckey J, Lee JH, LeRose JJ, Lindgren R, Liyanage N, Lubinsky N, Mammei J, Mammoliti F, Margaziotis DJ, Markowitz P, McCreary A, McNulty D, Mercado L, Meziani ZE, Michaels RW, Mihovilovic M, Muangma N, Muñoz-Camacho C, Nanda S, Nelyubin V, Nuruzzaman N, Oh Y, Palmer A, Parno D, Paschke KD, Phillips SK, Poelker B, Pomatsalyuk R, Posik M, Puckett AJR, Quinn B, Rakhman A, Reimer PE, Riordan S, Rogan P, Ron G, Russo G, Saenboonruang K, Saha A, Sawatzky B, Shahinyan A, Silwal R, Sirca S, Slifer K, Solvignon P, Souder PA, Sperduto ML, Subedi R, Suleiman R, Sulkosky V, Sutera CM, Tobias WA, Troth W, Urciuoli GM, Waidyawansa B, Wang D, Wexler J, Wilson R, Wojtsekhowski B, Yan X, Yao H, Ye Y, Ye Z, Yim V, Zana L, Zhan X, Zhang J, Zhang Y, Zheng X, Zhu P. Measurement of the neutron radius of 208Pb through parity violation in electron scattering. PHYSICAL REVIEW LETTERS 2012; 108:112502. [PMID: 22540469 DOI: 10.1103/physrevlett.108.112502] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Indexed: 05/31/2023]
Abstract
We report the first measurement of the parity-violating asymmetry A(PV) in the elastic scattering of polarized electrons from 208Pb. A(PV) is sensitive to the radius of the neutron distribution (R(n)). The result A(PV)=0.656±0.060(stat)±0.014(syst) ppm corresponds to a difference between the radii of the neutron and proton distributions R(n)-R(p)=0.33(-0.18)(+0.16) fm and provides the first electroweak observation of the neutron skin which is expected in a heavy, neutron-rich nucleus.
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17
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Ahmed Z, Allada K, Aniol KA, Armstrong DS, Arrington J, Baturin P, Bellini V, Benesch J, Beminiwattha R, Benmokhtar F, Canan M, Camsonne A, Cates GD, Chen JP, Chudakov E, Cisbani E, Dalton MM, de Jager CW, De Leo R, Deconinck W, Decowski P, Deng X, Deur A, Dutta C, Franklin GB, Friend M, Frullani S, Garibaldi F, Giusa A, Glamazdin A, Golge S, Grimm K, Hansen O, Higinbotham DW, Holmes R, Holmstrom T, Huang J, Huang M, Hyde CE, Jen CM, Jin G, Jones D, Kang H, King P, Kowalski S, Kumar KS, Lee JH, LeRose JJ, Liyanage N, Long E, McNulty D, Margaziotis D, Meddi F, Meekins DG, Mercado L, Meziani ZE, Michaels R, Muñoz-Camacho C, Mihovilovic M, Muangma N, Myers KE, Nanda S, Narayan A, Nelyubin V, Oh Y, Pan K, Parno D, Paschke KD, Phillips SK, Qian X, Qiang Y, Quinn B, Rakhman A, Reimer PE, Rider K, Riordan S, Roche J, Rubin J, Russo G, Saenboonruang K, Saha A, Sawatzky B, Silwal R, Sirca S, Souder PA, Sperduto M, Subedi R, Suleiman R, Sulkosky V, Sutera CM, Tobias WA, Urciuoli GM, Waidyawansa B, Wang D, Wexler J, Wilson R, Wojtsekhowski B, Zhan X, Yan X, Yao H, Ye L, Zhao B, Zheng X. New precision limit on the strange vector form factors of the proton. PHYSICAL REVIEW LETTERS 2012; 108:102001. [PMID: 22468841 DOI: 10.1103/physrevlett.108.102001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Indexed: 05/31/2023]
Abstract
The parity-violating cross-section asymmetry in the elastic scattering of polarized electrons from unpolarized protons has been measured at a four-momentum transfer squared Q2 = 0.624 GeV2 and beam energy E(b) = 3.48 GeV to be A(PV) = -23.80 ± 0.78(stat) ± 0.36(syst) parts per million. This result is consistent with zero contribution of strange quarks to the combination of electric and magnetic form factors G(E)(s) + 0.517G(M)(s) = 0.003 ± 0.010(stat) ± 0.004(syst) ± 0.009(ff), where the third error is due to the limits of precision on the electromagnetic form factors and radiative corrections. With this measurement, the world data on strange contributions to nucleon form factors are seen to be consistent with zero and not more than a few percent of the proton form factors.
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Affiliation(s)
- Z Ahmed
- Syracuse University, Syracuse, New York 13244, USA
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18
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Cates GD, de Jager CW, Riordan S, Wojtsekhowski B. Flavor decomposition of the elastic nucleon electromagnetic form factors. PHYSICAL REVIEW LETTERS 2011; 106:252003. [PMID: 21770634 DOI: 10.1103/physrevlett.106.252003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Indexed: 05/31/2023]
Abstract
The u- and d-quark contributions to the elastic nucleon electromagnetic form factors have been determined by using experimental data on G(E)(n), G(M)(n), G(E)(p), and G(M)(p). Such a flavor separation of the form factors became possible up to negative four-momentum transfer squared Q(2) = 3.4 GeV(2) with recent data on G(E)(n) from Hall A at Jefferson Lab. For Q(2) above 1 GeV(2), for both the u and the d quark, the ratio of the Pauli and Dirac form factors, F(2)/F(1), was found to be almost constant in sharp contrast to the behavior of F(2)/F(1) for the proton as a whole. Also, again for Q(2)>1 GeV(2), both F(2)(d) and F(1)(d) are roughly proportional to 1/Q(4), whereas the dropoff of F(2)(u) and F(1)(u) is more gradual.
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Affiliation(s)
- G D Cates
- University of Virginia, Charlottesville, Virginia 22903, USA
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19
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Androić D, Armstrong DS, Arvieux J, Bailey SL, Beck DH, Beise EJ, Benesch J, Benmokhtar F, Bimbot L, Birchall J, Bosted P, Breuer H, Capuano CL, Chao YC, Coppens A, Davis CA, Ellis C, Flores G, Franklin G, Furget C, Gaskell D, Gericke MTW, Grames J, Guillard G, Hansknecht J, Horn T, Jones M, King PM, Korsch W, Kox S, Lee L, Liu J, Lung A, Mammei J, Martin JW, McKeown RD, Mihovilovic M, Micherdzinska A, Mkrtchyan H, Muether M, Page SA, Papavassiliou V, Pate SF, Phillips SK, Pillot P, Pitt ML, Poelker M, Quinn B, Ramsay WD, Real JS, Roche J, Roos P, Schaub J, Seva T, Simicevic N, Smith GR, Spayde DT, Stutzman M, Suleiman R, Tadevosyan V, van Oers WTH, Versteegen M, Voutier E, Vulcan W, Wells SP, Williamson SE, Wood SA. Strange quark contributions to parity-violating asymmetries in the backward angle G0 electron scattering experiment. PHYSICAL REVIEW LETTERS 2010; 104:012001. [PMID: 20366359 DOI: 10.1103/physrevlett.104.012001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2009] [Indexed: 05/29/2023]
Abstract
We have measured parity-violating asymmetries in elastic electron-proton and quasielastic electron-deuteron scattering at Q2=0.22 and 0.63 GeV2. They are sensitive to strange quark contributions to currents in the nucleon and the nucleon axial-vector current. The results indicate strange quark contributions of approximately < 10% of the charge and magnetic nucleon form factors at these four-momentum transfers. We also present the first measurement of anapole moment effects in the axial-vector current at these four-momentum transfers.
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Affiliation(s)
- D Androić
- Department of Physics, University of Zagreb, Zagreb HR-41001, Croatia
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20
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Baunack S, Aulenbacher K, Balaguer Ríos D, Capozza L, Diefenbach J, Gläser B, von Harrach D, Imai Y, Kabuss EM, Kothe R, Lee JH, Merkel H, Mora Espí MC, Müller U, Schilling E, Stephan G, Weinrich C, Arvieux J, El-Yakoubi MA, Frascaria R, Kunne R, Maas FE, Morlet M, Ong S, van de Wiele J, Kowalski S, Prok Y, Taylor S. Measurement of strange quark contributions to the vector form factors of the proton at Q2 = 0.22 (GeV / c)2. PHYSICAL REVIEW LETTERS 2009; 102:151803. [PMID: 19518619 DOI: 10.1103/physrevlett.102.151803] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2008] [Indexed: 05/27/2023]
Abstract
A new measurement of the parity violating asymmetry in elastic electron scattering on hydrogen at backward angles and at a four momentum transfer of Q;{2} = 0.22 (Ge V / c);{2} is reported here. The measured asymmetry is A_{LR} = (-17.23 +/- 0.82_{stat} +/- 0.89_{syst}) x 10;{-6}. The standard model prediction assuming no strangeness is A_{0} = (-15.87 +/- 1.22) x 10;{-6}. In combination with previous results from measurements at forward angles, it is possible to disentangle for the first time the strange form factors at this momentum transfer, G_{E};{s} = 0.050 +/- 0.038 +/- 0.019 and G_{M};{s} = -0.14 +/- 0.11 +/- 0.11.
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Affiliation(s)
- S Baunack
- Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany.
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21
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Tjon JA, Melnitchouk W. Effect of two-boson exchange on parity-violating e-p scattering. PHYSICAL REVIEW LETTERS 2008; 100:082003. [PMID: 18352618 DOI: 10.1103/physrevlett.100.082003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2007] [Indexed: 05/26/2023]
Abstract
We compute the corrections from two-photon and gamma-Z exchange in parity-violating elastic electron-proton scattering, used to extract the strange form factors of the proton. We use a hadronic formalism that successfully reconciled the earlier discrepancy in the proton's electron to magnetic form factor ratio, suitably extended to the weak sector. Implementing realistic electroweak form factors, we find effects of the order 2%-3% at Q(2) less, similar0.1 GeV2, which are largest at backward angles and have a strong Q2 dependence at low Q2. Two-boson contributions to the weak axial current are found to be enhanced at low Q2 and for forward angles. We provide corrections at kinematics relevant for recent and upcoming parity-violating experiments.
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Affiliation(s)
- J A Tjon
- Physics Department, University of Utrecht, The Netherlands
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22
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Zhou HQ, Kao CW, Yang SN. Two-photon-exchange and gammaZ-exchange corrections to parity-violating elastic electron-proton scattering. PHYSICAL REVIEW LETTERS 2007; 99:262001. [PMID: 18233567 DOI: 10.1103/physrevlett.99.262001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2007] [Indexed: 05/25/2023]
Abstract
Leading electroweak corrections play an important role in precision measurements of the strange form factors. We calculate the two-photon-exchange (TPE) and gammaZ-exchange corrections to the parity-violating asymmetry of the elastic electron-proton scattering in a simple hadronic model including the finite size of the proton. We find both can reach a few percent and are comparable in size with the current experimental measurements of strange-quark effects in the proton neutral weak current. The effect of gammaZ exchange is in general larger than that of TPE, especially at low momentum transfer Q2</=1 GeV2. Their combined effects on the values of G(E)s + beta G(M)s [corrected] extracted in recent experiments can be as large as -40% in certain kinematics.
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Affiliation(s)
- Hai Qing Zhou
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan
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23
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Ron G, Glister J, Lee B, Allada K, Armstrong W, Arrington J, Beck A, Benmokhtar F, Berman BL, Boeglin W, Brash E, Camsonne A, Calarco J, Chen JP, Choi S, Chudakov E, Coman L, Craver B, Cusanno F, Dumas J, Dutta C, Feuerbach R, Freyberger A, Frullani S, Garibaldi F, Gilman R, Hansen O, Higinbotham DW, Holmstrom T, Hyde CE, Ibrahim H, Ilieva Y, de Jager CW, Jiang X, Jones MK, Kang H, Kelleher A, Khrosinkova E, Kuchina E, Kumbartzki G, LeRose JJ, Lindgren R, Markowitz P, May-Tal Beck S, McCullough E, Meekins D, Meziane M, Meziani ZE, Michaels R, Moffit B, Norum BE, Oh Y, Olson M, Paolone M, Paschke K, Perdrisat CF, Piasetzky E, Potokar M, Pomatsalyuk R, Pomerantz I, Puckett A, Punjabi V, Qian X, Qiang Y, Ransome R, Reyhan M, Roche J, Rousseau Y, Saha A, Sarty AJ, Sawatzky B, Schulte E, Shabestari M, Shahinyan A, Shneor R, Sirca S, Slifer K, Solvignon P, Song J, Sparks R, Subedi R, Strauch S, Urciuoli GM, Wang K, Wojtsekhowski B, Yan X, Yao H, Zhan X, Zhu X. Measurements of the proton elastic-form-factor ratio mu pG p E/G p M at low momentum transfer. PHYSICAL REVIEW LETTERS 2007; 99:202002. [PMID: 18233135 DOI: 10.1103/physrevlett.99.202002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2007] [Indexed: 05/25/2023]
Abstract
High-precision measurements of the proton elastic form-factor ratio, mu pG p E/G p M, have been made at four-momentum transfer, Q2, values between 0.2 and 0.5 GeV2. The new data, while consistent with previous results, clearly show a ratio less than unity and significant differences from the central values of several recent phenomenological fits. By combining the new form-factor ratio data with an existing cross-section measurement, one finds that in this Q2 range the deviation from unity is primarily due to G p E being smaller than expected.
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Affiliation(s)
- G Ron
- Tel Aviv University, Tel Aviv 69978, Israel
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24
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Young RD, Carlini RD, Thomas AW, Roche J. Testing the standard model by precision measurement of the weak charges of quarks. PHYSICAL REVIEW LETTERS 2007; 99:122003. [PMID: 17930499 DOI: 10.1103/physrevlett.99.122003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2007] [Indexed: 05/25/2023]
Abstract
In a global analysis of the latest parity-violating electron scattering measurements on nuclear targets, we demonstrate a significant improvement in the experimental knowledge of the weak neutral-current lepton-quark interactions at low energy. The precision of this new result, combined with earlier atomic parity-violation measurements, places tight constraints on the size of possible contributions from physics beyond the standard model. Consequently, this result improves the lower-bound on the scale of relevant new physics to approximately 1 TeV.
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Affiliation(s)
- R D Young
- Jefferson Lab, 12000 Jefferson Ave., Newport News, Virginia 23606, USA
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25
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Miller GA. Charge densities of the neutron and proton. PHYSICAL REVIEW LETTERS 2007; 99:112001. [PMID: 17930428 DOI: 10.1103/physrevlett.99.112001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2007] [Indexed: 05/25/2023]
Abstract
A model-independent analysis of the infinite-momentum-frame charge density of partons in the transverse plane is presented for the nucleon. We find that the neutron-parton charge density is negative at the center, so that the square of the transverse charge radius is positive, in contrast with many expectations. Additionally, the proton's central d quark charge density is larger than that of the u quark by about 30%. The proton (neutron) charge density has a long range positively (negatively) charged component.
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Affiliation(s)
- Gerald A Miller
- Department of Physics, University of Washington, Seattle, Washington 98195-1560, USA
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26
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Viviani M, Schiavilla R, Kubis B, Lewis R, Girlanda L, Kievsky A, Marcucci LE, Rosati S. Isospin mixing in the nucleon and 4He and the nucleon strange electric form factor. PHYSICAL REVIEW LETTERS 2007; 99:112002. [PMID: 17930429 DOI: 10.1103/physrevlett.99.112002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2007] [Indexed: 05/25/2023]
Abstract
In order to isolate the contribution of the nucleon strange electric form factor to the parity-violating asymmetry measured in 4He(e-->],e')4He experiments, it is crucial to have a reliable estimate of the magnitude of isospin-symmetry-breaking (ISB) corrections in both the nucleon and 4He. We examine this issue in the present Letter. Isospin admixtures in the nucleon are determined in chiral perturbation theory, while those in 4He are derived from nuclear interactions, including explicit ISB terms. A careful analysis of the model dependence in the resulting predictions for the nucleon and nuclear ISB contributions to the asymmetry is carried out. We conclude that, at the low momentum transfers of interest in recent measurements reported by the HAPPEX Collaboration at Jefferson Lab, these contributions are of comparable magnitude to those associated with strangeness components in the nucleon electric form factor.
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Affiliation(s)
- M Viviani
- INFN, Sezione di Pisa, and Department of Physics, University of Pisa, I-56127 Pisa, Italy
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27
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Dillon G, Morpurgo G. Baryon octet magnetic moments to all orders in flavor breaking: An application to the problem of the strangeness in the nucleon. Int J Clin Exp Med 2007. [DOI: 10.1103/physrevd.75.073007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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