1
|
Androić D, Armstrong DS, Bartlett K, Beminiwattha RS, Benesch J, Benmokhtar F, Birchall J, Carlini RD, Cornejo JC, Covrig Dusa S, Dalton MM, Davis CA, Deconinck W, Dowd JF, Dunne JA, Dutta D, Duvall WS, Elaasar M, Falk WR, Finn JM, Forest T, Gal C, Gaskell D, Gericke MTW, Gray VM, Grimm K, Guo F, Hoskins JR, Jones DC, Jones MK, 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, Mesick KE, Michaels R, Micherdzinska A, Mkrtchyan A, Mkrtchyan H, Narayan A, Ndukum LZ, Nelyubin V, van Oers WTH, Owen VF, Page SA, Pan J, Paschke KD, Phillips SK, Pitt ML, Radloff RW, Rajotte JF, Ramsay WD, Roche J, Sawatzky B, Seva T, Shabestari MH, Silwal R, Simicevic N, Smith GR, Solvignon P, Spayde DT, Subedi A, Suleiman R, Tadevosyan V, Tobias WA, Tvaskis V, Waidyawansa B, Wang P, Wells SP, Wood SA, Yang S, Zang P, Zhamkochyan S, Christy ME, Horowitz CJ, Fattoyev FJ, Lin Z. Determination of the ^{27}Al Neutron Distribution Radius from a Parity-Violating Electron Scattering Measurement. Phys Rev Lett 2022; 128:132501. [PMID: 35426696 DOI: 10.1103/physrevlett.128.132501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Accepted: 03/02/2022] [Indexed: 06/14/2023]
Abstract
We report the first measurement of the parity-violating elastic electron scattering asymmetry on ^{27}Al. The ^{27}Al elastic asymmetry is A_{PV}=2.16±0.11(stat)±0.16(syst) ppm, and was measured at ⟨Q^{2}⟩=0.02357±0.00010 GeV^{2}, ⟨θ_{lab}⟩=7.61°±0.02°, and ⟨E_{lab}⟩=1.157 GeV with the Q_{weak} apparatus at Jefferson Lab. Predictions using a simple Born approximation as well as more sophisticated distorted-wave calculations are in good agreement with this result. From this asymmetry the ^{27}Al neutron radius R_{n}=2.89±0.12 fm was determined using a many-models correlation technique. The corresponding neutron skin thickness R_{n}-R_{p}=-0.04±0.12 fm is small, as expected for a light nucleus with a neutron excess of only 1. This result thus serves as a successful benchmark for electroweak determinations of neutron radii on heavier nuclei. A tree-level approach was used to extract the ^{27}Al weak radius R_{w}=3.00±0.15 fm, and the weak skin thickness R_{wk}-R_{ch}=-0.04±0.15 fm. The weak form factor at this Q^{2} is F_{wk}=0.39±0.04.
Collapse
Affiliation(s)
- D Androić
- University of Zagreb, Zagreb, HR 10002, Croatia
| | | | - K Bartlett
- William & Mary, Williamsburg, Virginia 23185, USA
| | | | - J Benesch
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - F Benmokhtar
- Christopher Newport University, Newport News, Virginia 23606, USA
| | - J Birchall
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
| | - R D Carlini
- William & Mary, Williamsburg, Virginia 23185, USA
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - J C Cornejo
- William & Mary, Williamsburg, Virginia 23185, USA
| | - S Covrig Dusa
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - M M Dalton
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
- University of Virginia, Charlottesville, Virginia 22903, USA
| | - C A Davis
- TRIUMF, Vancouver, British Columbia V6T2A3, Canada
| | - W Deconinck
- William & Mary, Williamsburg, Virginia 23185, USA
| | - J F Dowd
- William & Mary, Williamsburg, Virginia 23185, USA
| | - J A Dunne
- Mississippi State University, Mississippi State, Mississippi 39762, USA
| | - D Dutta
- Mississippi State University, Mississippi State, Mississippi 39762, USA
| | - W S Duvall
- Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
| | - M Elaasar
- Southern University at New Orleans, New Orleans, Louisiana 70126, USA
| | - W R Falk
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
| | - J M Finn
- William & Mary, Williamsburg, Virginia 23185, USA
| | - T Forest
- Idaho State University, Pocatello, Idaho 83209, USA
- Louisiana Tech University, Ruston, Louisiana 71272, USA
| | - C Gal
- University of Virginia, Charlottesville, Virginia 22903, USA
| | - D Gaskell
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - M T W Gericke
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
| | - V M Gray
- William & Mary, Williamsburg, Virginia 23185, USA
| | - K Grimm
- William & Mary, Williamsburg, Virginia 23185, USA
- Louisiana Tech University, Ruston, Louisiana 71272, USA
| | - F Guo
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - J R Hoskins
- William & Mary, Williamsburg, Virginia 23185, USA
| | - D C Jones
- University of Virginia, Charlottesville, Virginia 22903, USA
| | - M K Jones
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | | | - P M King
- Ohio University, Athens, Ohio 45701, USA
| | - E Korkmaz
- University of Northern British Columbia, Prince George, British Columbia V2N4Z9, Canada
| | - S Kowalski
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - J Leacock
- Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
| | - J Leckey
- William & Mary, Williamsburg, Virginia 23185, USA
| | - A R Lee
- Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
| | - J H Lee
- William & Mary, Williamsburg, Virginia 23185, USA
- Ohio University, Athens, Ohio 45701, USA
| | - L Lee
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
- TRIUMF, Vancouver, British Columbia V6T2A3, Canada
| | - S MacEwan
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
| | - D Mack
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - J A Magee
- William & Mary, Williamsburg, Virginia 23185, USA
| | - R Mahurin
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
| | - J Mammei
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
- Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
| | - J W Martin
- University of Winnipeg, Winnipeg, Manitoba R3B2E9, Canada
| | - M J McHugh
- George Washington University, Washington, DC 20052, USA
| | - D Meekins
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - K E Mesick
- George Washington University, Washington, DC 20052, USA
- Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, USA
| | - R Michaels
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | | | - A Mkrtchyan
- A. I. Alikhanyan National Science Laboratory (Yerevan Physics Institute), Yerevan 0036, Armenia
| | - H Mkrtchyan
- A. I. Alikhanyan National Science Laboratory (Yerevan Physics Institute), Yerevan 0036, Armenia
| | - A Narayan
- Mississippi State University, Mississippi State, Mississippi 39762, USA
| | - L Z Ndukum
- Mississippi State University, Mississippi State, Mississippi 39762, USA
| | - V Nelyubin
- University of Virginia, Charlottesville, Virginia 22903, USA
| | - W T H van Oers
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
- TRIUMF, Vancouver, British Columbia V6T2A3, Canada
| | - V F Owen
- William & Mary, Williamsburg, Virginia 23185, USA
| | - S A Page
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
| | - J Pan
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
| | - K D Paschke
- University of Virginia, Charlottesville, Virginia 22903, USA
| | - S K Phillips
- University of New Hampshire, Durham, New Hampshire 03824, USA
| | - M L Pitt
- Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
| | | | - J F Rajotte
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - W D Ramsay
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
- TRIUMF, Vancouver, British Columbia V6T2A3, Canada
| | - J Roche
- Ohio University, Athens, Ohio 45701, USA
| | - B Sawatzky
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - T Seva
- University of Zagreb, Zagreb, HR 10002, Croatia
| | - M H Shabestari
- Mississippi State University, Mississippi State, Mississippi 39762, USA
| | - R Silwal
- University of Virginia, Charlottesville, Virginia 22903, USA
| | - N Simicevic
- Louisiana Tech University, Ruston, Louisiana 71272, USA
| | - G R Smith
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - P Solvignon
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - D T Spayde
- Hendrix College, Conway, Arkansas 72032, USA
| | - A Subedi
- Mississippi State University, Mississippi State, Mississippi 39762, USA
| | - R Suleiman
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - V Tadevosyan
- A. I. Alikhanyan National Science Laboratory (Yerevan Physics Institute), Yerevan 0036, Armenia
| | - W A Tobias
- University of Virginia, Charlottesville, Virginia 22903, USA
| | - V Tvaskis
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
- University of Winnipeg, Winnipeg, Manitoba R3B2E9, Canada
| | | | - P Wang
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
| | - S P Wells
- Louisiana Tech University, Ruston, Louisiana 71272, USA
| | - S A Wood
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - S Yang
- William & Mary, Williamsburg, Virginia 23185, USA
| | - P Zang
- Syracuse University, Syracuse, New York 13244, USA
| | - S Zhamkochyan
- A. I. Alikhanyan National Science Laboratory (Yerevan Physics Institute), Yerevan 0036, Armenia
| | - M E Christy
- Hampton University, Hampton, Virginia 23668, USA
| | - C J Horowitz
- Indiana University, Bloomington, Indiana 47405, USA
| | - F J Fattoyev
- Indiana University, Bloomington, Indiana 47405, USA
| | - Z Lin
- Indiana University, Bloomington, Indiana 47405, USA
| |
Collapse
|
2
|
Androić D, Armstrong DS, Asaturyan A, Bartlett K, Beaufait J, Beminiwattha RS, Benesch J, Benmokhtar F, Birchall J, Carlini RD, Cornejo JC, Dusa SC, Dalton MM, Davis CA, Deconinck W, Dowd JF, Dunne JA, Dutta D, Duvall WS, Elaasar M, Falk WR, Finn JM, Forest T, Gal C, Gaskell D, Gericke MTW, Grames J, Gray VM, Grimm K, Guo F, Hoskins JR, Jones D, Jones MK, Jones RT, Kargiantoulakis M, King PM, Korkmaz E, Kowalski S, Leacock J, Leckey JP, Lee AR, Lee JH, Lee L, MacEwan S, Mack D, Magee JA, Mahurin R, Mammei J, Martin JW, McHugh MJ, Meekins D, Mei J, Mesick KE, Michaels R, Micherdzinska A, Mkrtchyan A, Mkrtchyan H, Morgan N, Narayan A, Ndukum LZ, Nelyubin V, van Oers WTH, Owen VF, Page SA, Pan J, Paschke KD, Phillips SK, Pitt ML, Radloff RW, 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, Zang P, Zhamkochyan S. Precision Measurement of the Beam-Normal Single-Spin Asymmetry in Forward-Angle Elastic Electron-Proton Scattering. Phys Rev Lett 2020; 125:112502. [PMID: 32976004 DOI: 10.1103/physrevlett.125.112502] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 08/07/2020] [Accepted: 08/11/2020] [Indexed: 06/11/2023]
Abstract
A beam-normal single-spin asymmetry generated in the scattering of transversely polarized electrons from unpolarized nucleons is an observable related to the imaginary part of the two-photon exchange process. We report a 2% precision measurement of the beam-normal single-spin asymmetry in elastic electron-proton scattering with a mean scattering angle of θ_{lab}=7.9° and a mean energy of 1.149 GeV. The asymmetry result is B_{n}=-5.194±0.067(stat)±0.082 (syst) ppm. This is the most precise measurement of this quantity available to date and therefore provides a stringent test of two-photon exchange models at far-forward scattering angles (θ_{lab}→0) where they should be most reliable.
Collapse
Affiliation(s)
- D Androić
- University of Zagreb, Zagreb, HR 10002, Croatia
| | | | - A Asaturyan
- A. I. Alikhanyan National Science Laboratory (Yerevan Physics Institute), Yerevan 0036, Armenia
| | - K Bartlett
- William & Mary, Williamsburg, Virginia 23185, USA
| | - J Beaufait
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - R S Beminiwattha
- Ohio University, Athens, Ohio 45701, USA
- Louisiana Tech University, Ruston, Louisiana 71272, USA
| | - J Benesch
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - F Benmokhtar
- Duquesne University, Pittburgh, Pennsylvania 15282, USA
| | - J Birchall
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
| | - R D Carlini
- William & Mary, Williamsburg, Virginia 23185, USA
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - J C Cornejo
- William & Mary, Williamsburg, Virginia 23185, USA
| | - S Covrig Dusa
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - M M Dalton
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
- University of Virginia, Charlottesville, Virginia 22903, USA
| | - C A Davis
- TRIUMF, Vancouver, British Columbia V6T2A3, Canada
| | - W Deconinck
- William & Mary, Williamsburg, Virginia 23185, USA
| | - J F Dowd
- William & Mary, Williamsburg, Virginia 23185, USA
| | - J A Dunne
- Mississippi State University, Mississippi State, Mississippi 39762, USA
| | - D Dutta
- Mississippi State University, Mississippi State, Mississippi 39762, USA
| | - W S Duvall
- Virginia Polytechnic Institute & State University, Blacksburg, Virginia 24061, USA
| | - M Elaasar
- Southern University at New Orleans, New Orleans, Louisiana 70126, USA
| | - W R Falk
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
| | - J M Finn
- William & Mary, Williamsburg, Virginia 23185, USA
| | - T Forest
- Louisiana Tech University, Ruston, Louisiana 71272, USA
- Idaho State University, Pocatello, Idaho 83209, USA
| | - C Gal
- University of Virginia, Charlottesville, Virginia 22903, USA
| | - D Gaskell
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - M T W Gericke
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
| | - J Grames
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - V M Gray
- William & Mary, Williamsburg, Virginia 23185, USA
| | - K Grimm
- William & Mary, Williamsburg, Virginia 23185, USA
- Louisiana Tech University, Ruston, Louisiana 71272, USA
| | - F Guo
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - J R Hoskins
- William & Mary, Williamsburg, Virginia 23185, USA
| | - D Jones
- University of Virginia, Charlottesville, Virginia 22903, USA
| | - M K Jones
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - R T Jones
- University of Connecticut, Storrs-Mansfield, Connecticut 06269, USA
| | | | - P M King
- Ohio University, Athens, Ohio 45701, USA
| | - E Korkmaz
- University of Northern British Columbia, Prince George, British Columbia V2N4Z9, Canada
| | - S Kowalski
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - J Leacock
- Virginia Polytechnic Institute & State University, Blacksburg, Virginia 24061, USA
| | - J P Leckey
- William & Mary, Williamsburg, Virginia 23185, USA
| | - A R Lee
- Virginia Polytechnic Institute & State University, Blacksburg, Virginia 24061, USA
| | - J H Lee
- William & Mary, Williamsburg, Virginia 23185, USA
- Ohio University, Athens, Ohio 45701, USA
| | - L Lee
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
- TRIUMF, Vancouver, British Columbia V6T2A3, Canada
| | - S MacEwan
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
| | - D Mack
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - J A Magee
- William & Mary, Williamsburg, Virginia 23185, USA
| | - R Mahurin
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
| | - J Mammei
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
- Virginia Polytechnic Institute & State University, Blacksburg, Virginia 24061, USA
| | - J W Martin
- University of Winnipeg, Winnipeg, Manitoba R3B2E9, Canada
| | - M J McHugh
- George Washington University, Washington, DC 20052, USA
| | - D Meekins
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - J Mei
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - K E Mesick
- George Washington University, Washington, DC 20052, USA
- Rutgers, The State University of New Jersey, Piscataway, New Jersey 088754, USA
| | - R Michaels
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | | | - A Mkrtchyan
- A. I. Alikhanyan National Science Laboratory (Yerevan Physics Institute), Yerevan 0036, Armenia
| | - H Mkrtchyan
- A. I. Alikhanyan National Science Laboratory (Yerevan Physics Institute), Yerevan 0036, Armenia
| | - N Morgan
- Virginia Polytechnic Institute & State University, Blacksburg, Virginia 24061, USA
| | - A Narayan
- Mississippi State University, Mississippi State, Mississippi 39762, USA
| | - L Z Ndukum
- Mississippi State University, Mississippi State, Mississippi 39762, USA
| | - V Nelyubin
- University of Virginia, Charlottesville, Virginia 22903, USA
| | - W T H van Oers
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
- TRIUMF, Vancouver, British Columbia V6T2A3, Canada
| | - V F Owen
- William & Mary, Williamsburg, Virginia 23185, USA
| | - S A Page
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
| | - J Pan
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
| | - K D Paschke
- University of Virginia, Charlottesville, Virginia 22903, USA
| | - S K Phillips
- University of New Hampshire, Durham, New Hampshire 03824, USA
| | - M L Pitt
- Virginia Polytechnic Institute & State University, Blacksburg, Virginia 24061, USA
| | | | - J F Rajotte
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - W D Ramsay
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
- TRIUMF, Vancouver, British Columbia V6T2A3, Canada
| | - J Roche
- Ohio University, Athens, Ohio 45701, USA
| | - B Sawatzky
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - T Seva
- University of Zagreb, Zagreb, HR 10002, Croatia
| | - M H Shabestari
- Mississippi State University, Mississippi State, Mississippi 39762, USA
| | - R Silwal
- University of Virginia, Charlottesville, Virginia 22903, USA
| | - N Simicevic
- Louisiana Tech University, Ruston, Louisiana 71272, USA
| | - G R Smith
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - P Solvignon
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - D T Spayde
- Hendrix College, Conway, Arkansas 72032, USA
| | - A Subedi
- Mississippi State University, Mississippi State, Mississippi 39762, USA
| | - R Subedi
- George Washington University, Washington, DC 20052, USA
| | - R Suleiman
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - V Tadevosyan
- A. I. Alikhanyan National Science Laboratory (Yerevan Physics Institute), Yerevan 0036, Armenia
| | - W A Tobias
- University of Virginia, Charlottesville, Virginia 22903, USA
| | - V Tvaskis
- University of Winnipeg, Winnipeg, Manitoba R3B2E9, Canada
| | - B Waidyawansa
- Ohio University, Athens, Ohio 45701, USA
- Louisiana Tech University, Ruston, Louisiana 71272, USA
| | - P Wang
- University of Manitoba, Winnipeg, Manitoba R3T2N2, Canada
| | - S P Wells
- Louisiana Tech University, Ruston, Louisiana 71272, USA
| | - S A Wood
- Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
| | - S Yang
- William & Mary, Williamsburg, Virginia 23185, USA
| | - P Zang
- Syracuse University, Syracuse, New York 13244, USA
| | - S Zhamkochyan
- A. I. Alikhanyan National Science Laboratory (Yerevan Physics Institute), Yerevan 0036, Armenia
| |
Collapse
|
3
|
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. Phys Rev Lett 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] [What about the content of this article? (0)] [Affiliation(s)] [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.
Collapse
Affiliation(s)
- D Androic
- University of Zagreb, Zagreb HR-10002, Croatia
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
4
|
Abstract
Although much has been learned about the structure and function of Clp chaperones and their role in proteolysis, the mechanism of protein unfolding catalyzed by Clp ATPases and the mechanism of translocation of the unfolded proteins from Clp ATPases to partner proteases remain unsolved puzzles. However, models in which mechanical force is used to destabilize the structure of the substrate in a processive and directional manner are probable. It also seems likely that when ClpA ATPases are associated with proteases, unfolding is coupled to extrusion of the unfolded protein into the proteolytic cavity. In summary, it is anticipated that the large family of Clp ATPases will accomplish their many important cellular functions by similar mechanisms and what has been learned by studying the prokaryotic members reviewed here will shed a great deal of light on all members of the family.
Collapse
Affiliation(s)
- J R Hoskins
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | | | | | | |
Collapse
|
5
|
Abstract
The sigma(S) subunit of Escherichia coli RNA polymerase regulates the expression of stationary phase and stress response genes. Control over sigma(S) activity is exercised in part by regulated degradation of sigma(S). In vivo, degradation requires the ClpXP protease together with RssB, a protein homologous to response regulator proteins. Using purified components, we reconstructed the degradation of sigma(S) in vitro and demonstrate a direct role for RssB in delivering sigma(S) to ClpXP. RssB greatly stimulates sigma(S) degradation by ClpXP. Acetyl phosphate, which phosphorylates RssB, is required. RssB participates in multiple rounds of sigma(S) degradation, demonstrating its catalytic role. RssB promotes sigma(S) degradation specifically; it does not affect degradation of other ClpXP substrates or other proteins not normally degraded by ClpXP. sigma(S) and RssB form a stable complex in the presence of acetyl phosphate, and together they form a ternary complex with ClpX that is stabilized by ATP[gamma-S]. Alone, neither sigma(S) nor RssB binds ClpX with high affinity. When ClpP is present, a larger sigma(S)--RssB--ClpXP complex forms. The complex degrades sigma(S) and releases RssB from ClpXP in an ATP-dependent reaction. Our results illuminate an important mechanism for regulated protein turnover in which a unique targeting protein, whose own activity is regulated through specific signaling pathways, catalyzes the delivery of a specific substrate to a specific protease.
Collapse
Affiliation(s)
- Y Zhou
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892-4255, USA
| | | | | | | | | |
Collapse
|
6
|
Abstract
ClpA, a member of the Clp/Hsp100 ATPase family, is a molecular chaperone and regulatory component of ClpAP protease. We explored the mechanism of protein recognition by ClpA using a high affinity substrate, RepA, which is activated for DNA binding by ClpA and degraded by ClpAP. By characterizing RepA derivatives with N- or C-terminal deletions, we found that the N-terminal portion of RepA is required for recognition. More precisely, RepA derivatives lacking the N-terminal 5 or 10 amino acids are degraded by ClpAP at a rate similar to full-length RepA, whereas RepA derivatives lacking 15 or 20 amino acids are degraded much more slowly. Thus, ClpA recognizes an N-terminal signal in RepA beginning in the vicinity of amino acids 10-15. Moreover, peptides corresponding to RepA amino acids 4-13 and 1-15 inhibit interactions between ClpA and RepA. We constructed fusions of RepA and green fluorescent protein, a protein not recognized by ClpA, and found that the N-terminal 15 amino acids of RepA are sufficient to target the fusion protein for degradation by ClpAP. However, fusion proteins containing 46 or 70 N-terminal amino acids of RepA are degraded more efficiently in vitro and are noticeably stabilized in vivo in clpADelta and clpPDelta strains compared with wild type.
Collapse
Affiliation(s)
- J R Hoskins
- Laboratory of Molecular Biology, NCI, National Institutes of Health, Bethesda, Maryland 20892, USA
| | | | | |
Collapse
|
7
|
Singh SK, Grimaud R, Hoskins JR, Wickner S, Maurizi MR. Unfolding and internalization of proteins by the ATP-dependent proteases ClpXP and ClpAP. Proc Natl Acad Sci U S A 2000; 97:8898-903. [PMID: 10922052 PMCID: PMC16793 DOI: 10.1073/pnas.97.16.8898] [Citation(s) in RCA: 213] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
ClpX and ClpA are molecular chaperones that interact with specific proteins and, together with ClpP, activate their ATP-dependent degradation. The chaperone activity is thought to convert proteins into an extended conformation that can access the sequestered active sites of ClpP. We now show that ClpX can catalyze unfolding of a green fluorescent protein fused to a ClpX recognition motif (GFP-SsrA). Unfolding of GFP-SsrA depends on ATP hydrolysis. GFP-SsrA unfolded either by ClpX or by treatment with denaturants binds to ClpX in the presence of adenosine 5'-O-(3-thiotriphosphate) and is released slowly (t(1/2) approximately 15 min). Unlike ClpA, ClpX cannot trap unfolded proteins in stable complexes unless they also have a high-affinity binding motif. Addition of ATP or ADP accelerates release (t(1/2) approximately 1 min), consistent with a model in which ATP hydrolysis induces a conformation of ClpX with low affinity for unfolded substrates. Proteolytically inactive complexes of ClpXP and ClpAP unfold GFP-SsrA and translocate the protein to ClpP, where it remains unfolded. Complexes of ClpXP with translocated substrate within the ClpP chamber retain the ability to unfold GFP-SsrA. Our results suggest a bipartite mode of interaction between ClpX and substrates. ClpX preferentially targets motifs exposed in specific proteins. As the protein is unfolded by ClpX, additional motifs are exposed that facilitate its retention and favor its translocation to ClpP for degradation.
Collapse
Affiliation(s)
- S K Singh
- Laboratory of Cell Biology and Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | | | | | | | | |
Collapse
|
8
|
Abstract
ClpA, a bacterial member of the Clp/Hsp100 chaperone family, is an ATP-dependent molecular chaperone and the regulatory component of the ATP-dependent ClpAP protease. To study the mechanism of binding and unfolding of proteins by ClpA and translocation to ClpP, we used as a model substrate a fusion protein that joined the ClpA recognition signal from RepA to green fluorescent protein (GFP). ClpAP degrades the fusion protein in vivo and in vitro. The substrate binds specifically to ClpA in a reaction requiring ATP binding but not hydrolysis. Binding alone is not sufficient to destabilize the native structure of the GFP portion of the fusion protein. Upon ATP hydrolysis the GFP fusion protein is unfolded, and the unfolded intermediate can be sequestered by ClpA if a nonhydrolyzable analog is added to displace ATP. ATP is required for release. We found that although ClpA is unable to recognize native proteins lacking recognition signals, including GFP and rhodanese, it interacts with those same proteins when they are unfolded. Unfolded GFP is held in a nonnative conformation while associated with ClpA and its release requires ATP hydrolysis. Degradation of unfolded untagged proteins by ClpAP requires ATP even though the initial ATP-dependent unfolding reaction is bypassed. These results suggest that there are two ATP-requiring steps: an initial protein unfolding step followed by translocation of the unfolded protein to ClpP or in some cases release from the complex.
Collapse
Affiliation(s)
- J R Hoskins
- Laboratory of Molecular Biology and Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | | | | | | |
Collapse
|
9
|
Pak M, Hoskins JR, Singh SK, Maurizi MR, Wickner S. Concurrent chaperone and protease activities of ClpAP and the requirement for the N-terminal ClpA ATP binding site for chaperone activity. J Biol Chem 1999; 274:19316-22. [PMID: 10383442 DOI: 10.1074/jbc.274.27.19316] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
ClpA, a member of the Clp/Hsp100 family of ATPases, is both an ATP-dependent molecular chaperone and the regulatory component of ClpAP protease. We demonstrate that chaperone and protease activities occur concurrently in ClpAP complexes during a single round of RepA binding to ClpAP and ATP-dependent release. This result was substantiated with a ClpA mutant, ClpA(K220V), carrying an amino acid substitution in the N-terminal ATP binding site. ClpA(K220V) is unable to activate RepA, but the presence of ClpP or chemically inactivated ClpP restores its ability to activate RepA. The presence of ClpP simultaneously facilitates degradation of RepA. ClpP must remain bound to ClpA(K220V) for these effects, indicating that both chaperone and proteolytic activities of the mutant complex occur concurrently. ClpA(K220V) itself is able to form stable complexes with RepA in the presence of a poorly hydrolyzed ATP analog, adenosine 5'-O-(thiotriphosphate), and to release RepA upon exchange of adenosine 5'-O-(thiotriphosphate) with ATP. However, the released RepA is inactive in DNA binding, indicating that the N-terminal ATP binding site is essential for the chaperone activity of ClpA. Taken together, these results suggest that substrates bound to the complex of the proteolytic and ATPase components can be partitioned between release/reactivation and translocation/degradation.
Collapse
Affiliation(s)
- M Pak
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | | | | | | | | |
Collapse
|
10
|
Abstract
ClpA, a member of the Clp/Hsp100 family of ATPases, is a molecular chaperone and, in combination with a proteolytic component ClpP, participates in ATP-dependent proteolysis. We investigated the role of ClpA in protein degradation by ClpAP by dissociating the reaction into several discrete steps. In the assembly step, ClpA-ClpP-substrate complexes assemble either by ClpA-substrate complexes interacting with ClpP or by ClpA-ClpP complexes interacting with substrate; ClpP in the absence of ClpA is unable to bind substrates. Assembly requires ATP binding but not hydrolysis. We discovered that ClpA translocates substrates from their binding sites on ClpA to ClpP. The translocation step specifically requires ATP; nonhydrolyzable ATP analogs are ineffective. Only proteins that are degraded by ClpAP are translocated. Characterization of the degradation step showed that substrates can be degraded in a single round of ClpA-ClpP-substrate binding followed by ATP hydrolysis. The products generated are indistinguishable from steady-state products. Taken together, our results suggest that ClpA, through its interaction with both the substrate and ClpP, acts as a gatekeeper, actively translocating specific substrates into the proteolytic chamber of ClpP where degradation occurs. As multicomponent ATP-dependent proteases are widespread in nature and share structural similarities, these findings may provide a general mechanism for regulation of substrate import into the proteolytic chamber.
Collapse
Affiliation(s)
- J R Hoskins
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | | | | | | |
Collapse
|