共查询到20条相似文献,搜索用时 31 毫秒
1.
Andivahis L Bosted PE Lung A Stuart LM Alster J Arnold RG Chang CC Dietrich FS Dodge W Gearhart R Gomez J Griffioen KA Hicks RS Hyde-Wright CE Keppel C Kuhn SE Lichtenstadt J Miskimen RA Peterson GA Petratos GG Rock SE Rokni S Sakumoto WK Spengos M Swartz K Szalata Z Tao LH 《Physical review D: Particles and fields》1994,50(9):5491-5517
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Lung A Stuart LM Bosted PE Andivahis L Alster J Arnold RG Chang CC Dietrich FS Dodge WR Gearhart R Gomez J Griffioen KA Hicks RS Hyde-Wright CE Keppel C Kuhn SE Lichtenstadt J Miskimen RA Peterson GA Petratos GG Rock SE Rokni SH Sakumoto WK Spengos M Swartz K Szalata Z Tao LH 《Physical review letters》1993,70(6):718-721
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Walker RC Filippone BW Jourdan J Milner R McKeown R Potterveld D Andivahis L Arnold R Benton D Bosted P deChambrier G Lung A Rock SE Szalata ZM Para A Dietrich F Van Bibber K Button-Shafer J Debebe B Hicks RS Dasu S de Barbaro P Bodek A Harada H Krasny MW Lang K Riordan EM Gearhart R Whitlow LW Alster J 《Physical review D: Particles and fields》1994,49(11):5671-5689
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Maas FE Aulenbacher K Baunack S Capozza L Diefenbach J Gläser B Hammel T von Harrach D Imai Y Kabuss EM Kothe R Lee JH Lorente A Schilling E Schwaab D Sikora M Stephan G Weber G Weinrich C Altarev I Arvieux J El-Yakoubi M Frascaria R Kunne R Morlet M Ong S van de Wiele J Kowalski S Plaster B Suleiman R Taylor S 《Physical review letters》2005,94(15):152001
We report on a measurement of the parity violating asymmetry in the elastic scattering of polarized electrons off unpolarized protons with the A4 apparatus at MAMI in Mainz at a four momentum transfer value of Q(2)=0.108 (GeV/c)(2) and at a forward electron scattering angle of 30 degrees p)=[-1.36+/-0.29(stat)+/-0.13(syst)]x10(-6). The expectation from the standard model assuming no strangeness contribution to the vector current is A(0)=(-2.06+/-0.14)x10(-6). We have improved the statistical accuracy by a factor of 3 as compared to our previous measurements at a higher Q2. We have extracted the strangeness contribution to the electromagnetic form factors from our data to be G(s)(E)+0.106G(s)(M)=0.071+/-0.036 at Q(2)=0.108 (GeV/c)(2). We again find the value for G(s)(E)+0.106G(s)(M) to be positive, this time at an improved significance level of two sigma. 相似文献
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Maas FE Achenbach P Aulenbacher K Baunack S Capozza L Diefenbach J Grimm K Imai Y Hammel T von Harrach D Kabuss EM Kothe R Lee JH Lorente A Lopes Ginja A Nungesser L Schilling E Stephan G Weinrich C Altarev I Arvieux J Collin B Frascaria R Guidal M Kunne R Marchand D Morlet M Ong S van de Wiele J Kowalski S Plaster B Suleiman R Taylor S 《Physical review letters》2004,93(2):022002
We report on a measurement of the parity-violating asymmetry in the scattering of longitudinally polarized electrons on unpolarized protons at a Q2 of 0.230 (GeV/c)(2) and a scattering angle of theta (e) = 30 degrees - 40 degrees. Using a large acceptance fast PbF2 calorimeter with a solid angle of delta omega = 0.62 sr, the A4 experiment is the first parity violation experiment to count individual scattering events. The measured asymmetry is A(phys)=(-5.44+/-0.54(stat)+/-0.26(sys))x10(-6). The standard model expectation assuming no strangeness contributions to the vector form factors is A(0) = (-6.30+/-0.43) x 10(-6). The difference is a direct measurement of the strangeness contribution to the vector form factors of the proton. The extracted value is G(s)(E) + 0.225G(s)(M) = 0.039+/-0.034 or F(s)(1) + 0.130F(s)(2) = 0.032+/-0.028. 相似文献
7.
Electric and Magnetic form factors of neutron are calculated via electron-deuteron scattering at 1.511 ~5.507 GeV energy using SLAC group data. Our results show that the neutron electric form factor is not equal to zero;rather it has a small value, indicating that in spite of the fact that total charge is almost neutral, there is a nonuniformcharge distribution within the neutron, and that magnetic form factor follows the dipole fit. 相似文献
8.
Warren G Wesselmann F Zhu H McKee P Savvinov N Zeier M Aghalaryan A Ahmidouch A Arenhövel H Asaturyan R Ben-Dayan I Bloch F Boeglin W Boillat B Breuer H Brower J Carasco C Carl M Carlini R Cha J Chant N Christy E Cole L Coman L Coman M Crabb D Danagoulian S Day D Duek K Dunne J Elaasar M Ent R Farrell J Fatemi R Fawcett D Fenker H Forest T Garrow K Gasparian A Goussev I Gueye P Harvey M Hauger M Herrera R Hu B Jaegle I Jones M Jourdan J Keith C Kelly J Keppel C Khandaker M Klein A Klimenko A 《Physical review letters》2004,92(4):042301
The electric form factor of the neutron was determined from measurements of the d-->(e-->,e'n)p reaction for quasielastic kinematics. Polarized electrons were scattered off a polarized deuterated ammonia (15ND3) target in which the deuteron polarization was perpendicular to the momentum transfer. The scattered electrons were detected in a magnetic spectrometer in coincidence with neutrons in a large solid angle detector. We find G(n)(E)=0.0526+/-0.0033(stat)+/-0.0026(sys) and 0.0454+/-0.0054+/-0.0037 at Q(2)=0.5 and 1.0 (GeV/c)(2), respectively. 相似文献
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Horn T Aniol K Arrington J Barrett B Beise EJ Blok HP Boeglin W Brash EJ Breuer H Chang CC Christy ME Ent R Gaskell D Gibson E Holt RJ Huber GM Jin S Jones MK Keppel CE Kim W King PM Kovaltchouk V Liu J Lolos GJ Mack DJ Margaziotis DJ Markowitz P Matsumura A Meekins D Miyoshi T Mkrtchyan H Niculescu I Okayasu Y Pentchev L Perdrisat C Potterveld D Punjabi V Reimer P Reinhold J Roche J Roos PG Sarty A Smith GR Tadevosyan V Tang LG Tvaskis V Vidakovic S Volmer J Vulcan W Warren G Wood SA Xu C 《Physical review letters》2006,97(19):192001
The 1H(e,e'pi+)n cross section was measured at four-momentum transfers of Q2=1.60 and 2.45 GeV2 at an invariant mass of the photon nucleon system of W=2.22 GeV. The charged pion form factor (F(pi)) was extracted from the data by comparing the separated longitudinal pion electroproduction cross section to a Regge model prediction in which F(pi) is a free parameter. The results indicate that the pion form factor deviates from the charge-radius constrained monopole form at these values of Q2 by one sigma, but is still far from its perturbative quantum chromodynamics prediction. 相似文献
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Madey R Semenov AY Taylor S Plaster B Aghalaryan A Crouse E MacLachlan G Tajima S Tireman W Yan C Ahmidouch A Anderson BD Arenhövel H Asaturyan R Baker OK Baldwin AR Barkhuff D Breuer H Carlini R Christy E Churchwell S Cole L Danagoulian S Day D Eden T Elaasar M Ent R Farkhondeh M Fenker H Finn JM Gan L Garrow K Gasparian A Gueye P Howell CR Hu B Jones MK Kelly JJ Keppel C Khandaker M Kim WY Kowalski S Lai A Lung A Mack D Manley DM Markowitz P Mitchell J Mkrtchyan H Opper AK Perdrisat C 《Physical review letters》2003,91(12):122002
We report new measurements of the ratio of the electric form factor to the magnetic form factor of the neutron, G(n)(E)/G(n)(M), obtained via recoil polarimetry from the quasielastic 2H(e-->,e(')n-->)1H reaction at Q2 values of 0.45, 1.13, and 1.45 (GeV/c)(2) with relative statistical uncertainties of 7.6% and 8.4% at the two higher Q2 points, which points have never been achieved in polarization measurements. 相似文献
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Riordan S Abrahamyan S Craver B Kelleher A Kolarkar A Miller J Cates GD Liyanage N Wojtsekhowski B Acha A Allada K Anderson B Aniol KA Annand JR Arrington J Averett T Beck A Bellis M Boeglin W Breuer H Calarco JR Camsonne A Chen JP Chudakov E Coman L Crowe B Cusanno F Day D Degtyarenko P Dolph PA Dutta C Ferdi C Fernández-Ramírez C Feuerbach R Fraile LM Franklin G Frullani S Fuchs S Garibaldi F Gevorgyan N Gilman R Glamazdin A Gomez J Grimm K Hansen JO Herraiz JL Higinbotham DW Holmes R 《Physical review letters》2010,105(26):262302
The electric form factor of the neutron was determined from studies of the reaction 3He(e,e'n)pp in quasielastic kinematics in Hall A at Jefferson Lab. Longitudinally polarized electrons were scattered off a polarized target in which the nuclear polarization was oriented perpendicular to the momentum transfer. The scattered electrons were detected in a magnetic spectrometer in coincidence with neutrons that were registered in a large-solid-angle detector. More than doubling the Q2 range over which it is known, we find G(E)(n)=0.0236±0.0017(stat)±0.0026(syst), 0.0208±0.0024±0.0019, and 0.0147±0.0020±0.0014 for Q(2)=1.72, 2.48, and 3.41 GeV2, respectively. 相似文献
13.
Jan C. Bernauer 《Hyperfine Interactions》2011,200(1-3):23-26
An extensive measurement of the elastic H(e,e??)p reaction in the Q 2-region from 0.003 to 1 (GeV/c)2 has been performed with the three-spectrometer set-up of the A1 collaboration at the Mainz Microtron. The data set consists of about 3,000 overlapping cross-section measurements with a high level of internal redundancy, which allow for a determination of the electric and magnetic form factors with strict control over statistical and systematic errors, in particular also of the charge and magnetization radii of the proton. Besides the classical Rosenbluth separation, the form factors are separated by direct, global fits of different sufficiently flexible models. 相似文献
14.
Zhu H Ahmidouch A Anklin H Arenhövel H Armstrong C Bernet C Boeglin W Breuer H Brindza P Brown D Bültmann S Carlini R Chant N Cowley A Crabb D Danagoulian S Day DB Eden T Ent R Farah Y Fatemi R Garrow K Harris C Hauger M Honegger A Jourdan J Kaufmann M Khandaker M Kubon G Lichtenstadt J Lindgren R Lourie R Lung A Mack D Malik S Markowitz P McFarlane K McKee P McNulty D Milanovich G Mitchell J Mkrtchyan H Mühlbauer M Petitjean T Prok Y Rohe D Rollinde E Rondon OA Roos P Sawafta R Sick I Smith C 《Physical review letters》2001,87(8):081801
We report the first measurement using a solid polarized target of the neutron electric form factor G(n)(E) via d-->(e-->,e(')n)p. G(n)(E) was determined from the beam-target asymmetry in the scattering of longitudinally polarized electrons from polarized deuterated ammonia ( 15ND3). The measurement was performed in Hall C at Thomas Jefferson National Accelerator Facility in quasifree kinematics with the target polarization perpendicular to the momentum transfer. The electrons were detected in a magnetic spectrometer in coincidence with neutrons in a large solid angle segmented detector. We find G(n)(E) = 0.04632+/-0.00616(stat)+/-0.00341(syst) at Q2 = 0.495 (GeV/c)(2). 相似文献
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Rvachev MM Benmokhtar F Penel-Nottaris E Aniol KA Bertozzi W Boeglin WU Butaru F Calarco JR Chai Z Chang CC Chen JP Chudakov E Cisbani E Cochran A Cornejo J Dieterich S Djawotho P Duran W Epstein MB Finn JM Fissum KG Frahi-Amroun A Frullani S Furget C Garibaldi F Gayou O Gilad S Gilman R Glashausser C Hansen JO Higinbotham DW Hotta A Hu B Iodice M Iomni R de Jager CW Jiang X Jones MK Kelly JJ Kox S Kuss M Laget JM De Leo R Lerose JJ Liatard E Lindgren R Liyanage N Lourie RW Malov S 《Physical review letters》2005,94(19):192302
We have studied the quasielastic 3He(e,e(')p)2H reaction in perpendicular coplanar kinematics, with the energy and the momentum transferred by the electron fixed at 840 MeV and 1502 MeV/c, respectively. The 3He(e,e(')p)2H cross section was measured for missing momenta up to 1000 MeV/c, while the A(TL) asymmetry was extracted for missing momenta up to 660 MeV/c. For missing momenta up to 150 MeV/c, the cross section is described by variational calculations using modern 3He wave functions. For missing momenta from 150 to 750 MeV/c, strong final-state interaction effects are observed. Near 1000 MeV/c, the experimental cross section is more than an order of magnitude larger than predicted by available theories. The A(TL) asymmetry displays characteristic features of broken factorization with a structure that is similar to that generated by available models. 相似文献
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Bernauer JC Achenbach P Ayerbe Gayoso C Böhm R Bosnar D Debenjak L Distler MO Doria L Esser A Fonvieille H Friedrich JM Friedrich J Gómez Rodríguez de la Paz M Makek M Merkel H Middleton DG Müller U Nungesser L Pochodzalla J Potokar M Sánchez Majos S Schlimme BS Sirca S Walcher T Weinriefer M;A Collaboration 《Physical review letters》2010,105(24):242001
New precise results of a measurement of the elastic electron-proton scattering cross section performed at the Mainz Microtron MAMI are presented. About 1400 cross sections were measured with negative four-momentum transfers squared up to Q2 = 1 (GeV/c)2 with statistical errors below 0.2%. The electric and magnetic form factors of the proton were extracted by fits of a large variety of form factor models directly to the cross sections. The form factors show some features at the scale of the pion cloud. The charge and magnetic radii are determined to be ? = 0.879(5)stat(4)syst(2)model(4)group fm and ? = 0.777(13)stat(9)syst(5)model(2)group fm. 相似文献
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Bourgeois P Sato Y Shaw J Alarcon R Bernstein AM Bertozzi W Botto T Calarco J Casagrande F Distler MO Dow K Farkondeh M Georgakopoulos S Gilad S Hicks R Holtrop M Hotta A Jiang X Karabarbounis A Kirkpatrick J Kowalski S Milner R Miskimen R Nakagawa I Papanicolas CN Sarty AJ Sirca S Six E Sparveris NF Stave S Stiliaris E Tamae T Tsentalovich G Tschalaer C Turchinetz W Zhou ZL Zwart T 《Physical review letters》2006,97(21):212001
The mean square polarizability radii of the proton have been measured for the first time in a virtual-Compton-scattering experiment performed at the MIT-Bates out-of-plane scattering facility. Response functions and polarizabilities obtained from a dispersion analysis of the data at Q2 = 0.057 GeV2/c2 are in agreement with O(p3) heavy baryon chiral perturbation theory. The data support the dominance of mesonic effects in the polarizabilities. 相似文献
19.
We propose a two parameter expression for the high momentum transfer behaviour of the ratio of proton form factors GM(Q2)/QE(Q2) based on perturbation theory calculations in Quantum Chromodynamics. A fit to the present experimental data and its consistency with a previous fit to the high Q2 behaviour of the Dirac form factor [1] is also discussed. 相似文献
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Strauch S Dieterich S Aniol KA Annand JR Baker OK Bertozzi W Boswell M Brash EJ Chai Z Chen JP Christy ME Chudakov E Cochran A De Leo R Ent R Epstein MB Finn JM Fissum KG Forest TA Frullani S Garibaldi F Gasparian A Gayou O Gilad S Gilman R Glashausser C Gomez J Gorbenko V Gueye PL Hansen JO Higinbotham DW Hu B Hyde-Wright CE Ireland DG Jackson C de Jager CW Jiang X Jones C Jones MK Kellie JD Kelly JJ Keppel CE Kumbartzki G Kuss M LeRose JJ Livingston K Liyanage N Malov S Margaziotis DJ 《Physical review letters》2003,91(5):052301
We have measured the proton recoil polarization in the 4He(e-->,e(')p-->)4H reaction at Q(2)=0.5, 1.0, 1.6, and 2.6 (GeV/c)(2). The measured ratio of polarization transfer coefficients differs from a fully relativistic calculation, favoring the inclusion of a medium modification of the proton form factors predicted by a quark-meson coupling model. In addition, the measured induced polarizations agree reasonably well with the fully relativistic calculation indicating that the treatment of final-state interactions is under control. 相似文献