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31 results on '"Christy ME"'

1. Novel Measurement of the Neutron Magnetic Form Factor from A=3 Mirror Nuclei

Author

Santiesteban, SN, Li, S, Abrams, D, Alsalmi, S, Androic, D, Aniol, K, Arrington, J, Averett, T, Gayoso, C Ayerbe, Bane, J, Barcus, S, Barrow, J, Beck, A, Bellini, V, Bhatt, H, Bhetuwal, D, Biswas, D, Camsonne, A, Castellanos, J, Chen, J, Chen, J-P, Chrisman, D, Christy, ME, Clarke, C, Covrig, S, Cruz-Torres, R, Day, D, Dutta, D, Fuchey, E, Gal, C, Garibaldi, F, Gautam, TN, Gogami, T, Gomez, J, Guèye, P, Hague, TJ, Hansen, JO, Hauenstein, F, Henry, W, Higinbotham, DW, Holt, RJ, Hyde, C, Itabashi, K, Kaneta, M, Karki, A, Katramatou, AT, Keppel, CE, King, PM, Kurbany, L, Kutz, T, Lashley-Colthirst, N, Li, WB, Liu, H, Liyanage, N, Long, E, Lovato, A, Mammei, J, Markowitz, P, McClellan, RE, Meddi, F, Meekins, D, Michaels, R, Mihovilovič, M, Moyer, A, Nagao, S, Nguyen, D, Nycz, M, Olson, M, Ou, L, Owen, V, Palatchi, C, Pandey, B, Papadopoulou, A, Park, S, Petkovic, T, Premathilake, S, Punjabi, V, Ransome, RD, Reimer, PE, Reinhold, J, Riordan, S, Rocco, N, Rodriguez, VM, Schmidt, A, Schmookler, B, Segarra, EP, Shahinyan, A, Širca, S, Slifer, K, Solvignon, P, Su, T, Suleiman, R, Tang, L, Tian, Y, Tireman, W, Tortorici, F, Toyama, Y, Uehara, K, Urciuoli, GM, and Votaw, D

Subjects
Nuclear and Plasma Physics, Synchrotrons and Accelerators, Physical Sciences, Jefferson Lab Hall A Collaboration, Mathematical Sciences, Engineering, General Physics, Mathematical sciences, Physical sciences
Abstract

The electromagnetic form factors of the proton and neutron encode information on the spatial structure of their charge and magnetization distributions. While measurements of the proton are relatively straightforward, the lack of a free neutron target makes measurements of the neutron's electromagnetic structure more challenging and more sensitive to experimental or model-dependent uncertainties. Various experiments have attempted to extract the neutron form factors from scattering from the neutron in deuterium, with different techniques providing different, and sometimes large, systematic uncertainties. We present results from a novel measurement of the neutron magnetic form factor using quasielastic scattering from the mirror nuclei ^{3}H and ^{3}He, where the nuclear effects are larger than for deuterium but expected to largely cancel in the cross-section ratios. We extracted values of the neutron magnetic form factor for low-to-modest momentum transfer, 0.6

Published
2024

2. Deeply Virtual Compton Scattering Cross Section at High Bjorken x_{B}.

Author

Georges, F, Rashad, MNH, Stefanko, A, Dlamini, M, Karki, B, Ali, SF, Lin, P-J, Ko, H-S, Israel, N, Adikaram, D, Ahmed, Z, Albataineh, H, Aljawrneh, B, Allada, K, Allison, S, Alsalmi, S, Androic, D, Aniol, K, Annand, J, Atac, H, Averett, T, Ayerbe Gayoso, C, Bai, X, Bane, J, Barcus, S, Bartlett, K, Bellini, V, Beminiwattha, R, Bericic, J, Biswas, D, Brash, E, Bulumulla, D, Campbell, J, Camsonne, A, Carmignotto, M, Castellano, J, Chen, C, Chen, J-P, Chetry, T, Christy, ME, Cisbani, E, Clary, B, Cohen, E, Compton, N, Cornejo, JC, Covrig Dusa, S, Crowe, B, Danagoulian, S, Danley, T, De Persio, F, Deconinck, W, Defurne, M, Desnault, C, Di, D, Duer, M, Duran, B, Ent, R, Fanelli, C, Franklin, G, Fuchey, E, Gal, C, Gaskell, D, Gautam, T, Glamazdin, O, Gnanvo, K, Gray, VM, Gu, C, Hague, T, Hamad, G, Hamilton, D, Hamilton, K, Hansen, O, Hauenstein, F, Henry, W, Higinbotham, DW, Holmstrom, T, Horn, T, Huang, Y, Huber, GM, Hyde, CE, Ibrahim, H, Jen, C-M, Jin, K, Jones, M, Kabir, A, Keppel, C, Khachatryan, V, King, PM, Li, S, Li, WB, Liu, J, Liu, H, Liyanage, A, Magee, J, Malace, S, Mammei, J, Markowitz, P, McClellan, E, Mazouz, M, and Meddi, F

Subjects
Jefferson Lab Hall A Collaboration, Mathematical Sciences, Physical Sciences, Engineering, General Physics
Abstract

We report high-precision measurements of the deeply virtual Compton scattering (DVCS) cross section at high values of the Bjorken variable x_{B}. DVCS is sensitive to the generalized parton distributions of the nucleon, which provide a three-dimensional description of its internal constituents. Using the exact analytic expression of the DVCS cross section for all possible polarization states of the initial and final electron and nucleon, and final state photon, we present the first experimental extraction of all four helicity-conserving Compton form factors (CFFs) of the nucleon as a function of x_{B}, while systematically including helicity flip amplitudes. In particular, the high accuracy of the present data demonstrates sensitivity to some very poorly known CFFs.

Published
2022

3. Form Factors and Two-Photon Exchange in High-Energy Elastic Electron-Proton Scattering

Author

Christy, ME, Gautam, T, Ou, L, Schmookler, B, Wang, Y, Adikaram, D, Ahmed, Z, Albataineh, H, Ali, SF, Aljawrneh, B, Allada, K, Allison, SL, Alsalmi, S, Androic, D, Aniol, K, Annand, J, Arrington, J, Atac, H, Averett, T, Gayoso, C Ayerbe, Bai, X, Bane, J, Barcus, S, Bartlett, K, Bellini, V, Beminiwattha, R, Bericic, J, Bhatt, H, Bhetuwal, D, Biswas, D, Brash, E, Bulumulla, D, Camacho, CM, Campbell, J, Camsonne, A, Carmignotto, M, Castellanos, J, Chen, C, Chen, J-P, Chetry, T, Cisbani, E, Clary, B, Cohen, E, Compton, N, Cornejo, JC, Dusa, S Covrig, Crowe, B, Danagoulian, S, Danley, T, Deconinck, W, Defurne, M, Desnault, C, Di, D, Dlamini, M, Duer, M, Duran, B, Ent, R, Fanelli, C, Fuchey, E, Gal, C, Gaskell, D, Georges, F, Gilad, S, Glamazdin, O, Gnanvo, K, Gramolin, AV, Gray, VM, Gu, C, Habarakada, A, Hague, T, Hamad, G, Hamilton, D, Hamilton, K, Hansen, O, Hauenstein, F, Hernandez, AV, Henry, W, Higinbotham, DW, Holmstrom, T, Horn, T, Huang, Y, Huber, GM, Hyde, C, Ibrahim, H, Israel, N, Jen, C-M, Jin, K, Jones, M, Kabir, A, Karki, B, Keppel, C, Khachatryan, V, King, PM, Li, S, Li, W, Liu, H, Liu, J, Liyanage, AH, Mack, D, and Magee, J

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Mathematical Sciences, Engineering, General Physics, Mathematical sciences, Physical sciences
Abstract

We present new precision measurements of the elastic electron-proton scattering cross section for momentum transfer (Q^{2}) up to 15.75  (GeV/c)^{2}. Combined with existing data, these provide an improved extraction of the proton magnetic form factor at high Q^{2} and double the range over which a longitudinal or transverse separation of the cross section can be performed. The difference between our results and polarization data agrees with that observed at lower Q^{2} and attributed to hard two-photon exchange (TPE) effects, extending to 8  (GeV/c)^{2} the range of Q^{2} for which a discrepancy is established at >95% confidence. We use the discrepancy to quantify the size of TPE contributions needed to explain the cross section at high Q^{2}.

Published
2022

4. Deep Exclusive Electroproduction of π0 at High Q2 in the Quark Valence Regime

Author

Dlamini, M, Karki, B, Ali, SF, Lin, P-J, Georges, F, Ko, H-S, Israel, N, Rashad, MNH, Stefanko, A, Adikaram, D, Ahmed, Z, Albataineh, H, Aljawrneh, B, Allada, K, Allison, S, Alsalmi, S, Androic, D, Aniol, K, Annand, J, Atac, H, Averett, T, Ayerbe Gayoso, C, Bai, X, Bane, J, Barcus, S, Bartlett, K, Bellini, V, Beminiwattha, R, Bericic, J, Biswas, D, Brash, E, Bulumulla, D, Campbell, J, Camsonne, A, Carmignotto, M, Castellano, J, Chen, C, Chen, J-P, Chetry, T, Christy, ME, Cisbani, E, Clary, B, Cohen, E, Compton, N, Cornejo, JC, Covrig Dusa, S, Crowe, B, Danagoulian, S, Danley, T, De Persio, F, Deconinck, W, Defurne, M, Desnault, C, Di, D, Duer, M, Duran, B, Ent, R, Fanelli, C, Franklin, G, Fuchey, E, Gal, C, Gaskell, D, Gautam, T, Glamazdin, O, Gnanvo, K, Gray, VM, Gu, C, Hague, T, Hamad, G, Hamilton, D, Hamilton, K, Hansen, O, Hauenstein, F, Henry, W, Higinbotham, DW, Holmstrom, T, Horn, T, Huang, Y, Huber, GM, Hyde, C, Ibrahim, H, Jen, C-M, Jin, K, Jones, M, Kabir, A, Keppel, C, Khachatryan, V, King, PM, Li, S, Li, W, Liu, J, Liu, H, Liyanage, A, Magee, J, Malace, S, Mammei, J, Markowitz, P, McClellan, E, Meddi, F, and Meekins, D

Subjects
Jefferson Lab Hall A Collaboration, Mathematical Sciences, Physical Sciences, Engineering, General Physics
Abstract

We report measurements of the exclusive neutral pion electroproduction cross section off protons at large values of x_{B} (0.36, 0.48, and 0.60) and Q^{2} (3.1 to 8.4  GeV^{2}) obtained from Jefferson Lab Hall A experiment E12-06-014. The corresponding structure functions dσ_{T}/dt+εdσ_{L}/dt, dσ_{TT}/dt, dσ_{LT}/dt, and dσ_{LT^{'}}/dt are extracted as a function of the proton momentum transfer t-t_{min}. The results suggest the amplitude for transversely polarized virtual photons continues to dominate the cross section throughout this kinematic range. The data are well described by calculations based on transversity generalized parton distributions coupled to a helicity flip distribution amplitude of the pion, thus providing a unique way to probe the structure of the nucleon.

Published
2021

5. Unique Access to u-Channel Physics: Exclusive Backward-Angle Omega Meson Electroproduction

Author

Li, WB, Huber, GM, Blok, HP, Gaskell, D, Horn, T, Semenov-Tian-Shansky, K, Pire, B, Szymanowski, L, Laget, J-M, Aniol, K, Arrington, J, Beise, EJ, Boeglin, W, Brash, EJ, Breuer, H, Chang, CC, Christy, ME, Ent, R, Gibson, EF, Holt, RJ, 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, PE, Reinhold, J, Roche, J, Roos, PG, Sarty, A, Smith, GR, Tadevosyan, V, Tang, LG, Tvaskis, V, Volmer, J, Vulcan, W, Warren, G, Wood, SA, Xu, C, and Zheng, X

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Jefferson Lab Fπ Collaboration, Mathematical Sciences, Engineering, General Physics, Mathematical sciences, Physical sciences
Abstract

Backward-angle meson electroproduction above the resonance region, which was previously ignored, is anticipated to offer unique access to the three quark plus sea component of the nucleon wave function. In this Letter, we present the first complete separation of the four electromagnetic structure functions above the resonance region in exclusive ω electroproduction off the proton, ep→e^{'}pω, at central Q^{2} values of 1.60, 2.45  GeV^{2}, at W=2.21  GeV. The results of our pioneering -u≈-u_{min} study demonstrate the existence of a unanticipated backward-angle cross section peak and the feasibility of full L/T/LT/TT separations in this never explored kinematic territory. At Q^{2}=2.45  GeV^{2}, the observed dominance of σ_{T} over σ_{L}, is qualitatively consistent with the collinear QCD description in the near-backward regime, in which the scattering amplitude factorizes into a hard subprocess amplitude and baryon to meson transition distribution amplitudes: universal nonperturbative objects only accessible through backward-angle kinematics.

Published
2019

6. Measurements of Nonsinglet Moments of the Nucleon Structure Functions and Comparison to Predictions from Lattice QCD for Q2=4 GeV2

Author

Albayrak, I, Mamyan, V, Christy, ME, Ahmidouch, A, Arrington, J, Asaturyan, A, Bodek, A, Bosted, P, Bradford, R, Brash, E, Bruell, A, Butuceanu, C, Coleman, SJ, Commisso, M, Connell, SH, Dalton, MM, Danagoulian, S, Daniel, A, Day, DB, Dhamija, S, Dunne, J, Dutta, D, Ent, R, Gaskell, D, Gasparian, A, Gran, R, Horn, T, Huang, Liting, Huber, GM, Jayalath, C, Johnson, M, Jones, MK, Kalantarians, N, Liyanage, A, Keppel, CE, Kinney, E, Li, Y, Malace, S, Manly, S, Markowitz, P, Maxwell, J, Mbianda, NN, McFarland, KS, Meziane, M, Meziani, ZE, Mills, GB, Mkrtchyan, H, Mkrtchyan, A, Mulholland, J, Nelson, J, Niculescu, G, Niculescu, I, Pentchev, L, Puckett, A, Punjabi, V, Qattan, IA, Reimer, PE, Reinhold, J, Rodriguez, VM, Rondon-Aramayo, O, Sakuda, M, Sakumoto, WK, Segbefia, E, Seva, T, Sick, I, Slifer, K, Smith, GR, Steinman, J, Solvignon, P, Tadevosyan, V, Tajima, S, Tvaskis, V, Vulcan, WF, Walton, T, Wesselmann, FR, Wood, SA, and Ye, Zhihong

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, E06-009 Collaboration, nucl-ex, Mathematical Sciences, Engineering, General Physics, Mathematical sciences, Physical sciences
Abstract

We present extractions of the nucleon nonsinglet moments utilizing new precision data on the deuteron F_{2} structure function at large Bjorken-x determined via the Rosenbluth separation technique at Jefferson Lab Experimental Hall C. These new data are combined with a complementary set of data on the proton previously measured in Hall C at similar kinematics and world datasets on the proton and deuteron at lower x measured at SLAC and CERN. The new Jefferson Lab data provide coverage of the upper third of the x range, crucial for precision determination of the higher moments. In contrast to previous extractions, these moments have been corrected for nuclear effects in the deuteron using a new global fit to the deuteron and proton data. The obtained experimental moments represent an order of magnitude improvement in precision over previous extractions using high x data. Moreover, recent exciting developments in lattice QCD calculations provide a first ever comparison of these new experimental results with calculations of moments carried out at the physical pion mass, as well as a new approach that first calculates the quark distributions directly before determining moments.

Published
2019

7. Determination of the ^{27}Al Neutron Distribution Radius from a Parity-Violating Electron Scattering Measurement.

Author

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, Nuruzzaman, 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, and Lin Z

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.

Published
2022
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8. Probing the Deuteron at Very Large Internal Momenta.

Author

Yero C, Abrams D, Ahmed Z, Ahmidouch A, Aljawrneh B, Alsalmi S, Ambrose R, Armstrong W, Asaturyan A, Assumin-Gyimah K, Ayerbe Gayoso C, Bandari A, Bane J, Basnet S, Berdnikov VV, Bericic J, Bhatt H, Bhetuwal D, Biswas D, Boeglin WU, Bosted P, Brash E, Bukhari MHS, Chen H, Chen JP, Chen M, Christy ME, Covrig S, Craycraft K, Danagoulian S, Day D, Diefenthaler M, Dlamini M, Dunne J, Duran B, Dutta D, Ent R, Evans R, Fenker H, Fomin N, Fuchey E, Gaskell D, Gautam TN, Gonzalez FA, Hansen JO, Hauenstein F, Hernandez AV, Horn T, Huber GM, Jones MK, Joosten S, Kabir ML, Karki A, Keppel CE, Khanal A, King P, Kinney E, Lashley-Colthirst N, Li S, Li WB, Liyanage AH, Mack DJ, Malace SP, Matter J, Meekins D, Michaels R, Mkrtchyan A, Mkrtchyan H, Nazeer SJ, Nanda S, Niculescu G, Niculescu M, Nguyen D, Nuruzzaman N, Pandey B, Park S, Perdrisat CF, Pooser E, Rehfuss M, Reinhold J, Sawatzky B, Smith GR, Sun A, Szumila-Vance H, Tadevosyan V, Wood SA, and Zhang J

Abstract

We measure ^{2}H(e,e^{'}p)n cross sections at 4-momentum transfers of Q^{2}=4.5±0.5  (GeV/c)^{2} over a range of neutron recoil momenta p_{r}, reaching up to ∼1.0  GeV/c. We obtain data at fixed neutron recoil angles θ_{nq}=35°, 45°, and 75° with respect to the 3-momentum transfer q[over →]. The new data agree well with previous data, which reached p_{r}∼500  MeV/c. At θ_{nq}=35° and 45°, final state interactions, meson exchange currents, and isobar currents are suppressed and the plane wave impulse approximation provides the dominant cross section contribution. We compare the new data to recent theoretical calculations, where we observe a significant discrepancy for recoil momenta p_{r}>700  MeV/c.

Published
2020
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9. Revealing Color Forces with Transverse Polarized Electron Scattering.

Author

Armstrong W, Kang H, Liyanage A, Maxwell J, Mulholland J, Ndukum L, Ahmidouch A, Albayrak I, Asaturyan A, Ates O, Baghdasaryan H, Boeglin W, Bosted P, Brash E, Butuceanu C, Bychkov M, Carter P, Chen C, Chen JP, Choi S, Christy ME, Covrig S, Crabb D, Danagoulian S, Daniel A, Davidenko AM, Davis B, Day D, Deconinck W, Deur A, Dunne J, Dutta D, El Fassi L, Ellis C, Ent R, Flay D, Frlez E, Gaskell D, Geagla O, German J, Gilman R, Gogami T, Gomez J, Goncharenko YM, Hashimoto O, Higinbotham D, Horn T, Huber GM, Jones M, Jones MK, Kalantarians N, Kang HK, Kawama D, Keith C, Keppel C, Khandaker M, Kim Y, King PM, Kohl M, Kovacs K, Kubarovsky V, Li Y, Liyanage N, Luo W, Mack D, Mamyan V, Markowitz P, Maruta T, Meekins D, Melnik YM, Meziani ZE, Mkrtchyan A, Mkrtchyan H, Mochalov VV, Monaghan P, Narayan A, Nakamura SN, Nuruzzaman A, Pentchev L, Pocanic D, Posik M, Puckett A, Qiu X, Reinhold J, Riordan S, Roche J, Rondón OA, Sawatzky B, Shabestari M, Slifer K, Smith G, Soloviev LF, Solvignon P, Tadevosyan V, Tang L, Vasiliev AN, Veilleux M, Walton T, Wesselmann F, Wood S, Yao H, Ye Z, Zhang J, and Zhu L

Abstract

The Spin Asymmetries of the Nucleon Experiment measured two double spin asymmetries using a polarized proton target and polarized electron beam at two beam energies, 4.7 and 5.9 GeV. A large-acceptance open-configuration detector package identified scattered electrons at 40° and covered a wide range in Bjorken x (0.3

Published
2019
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10. Measurement of coherent production of π(±) in neutrino and antineutrino beams on carbon from Eν of 1.5 to 20 GeV.

Author

Higuera A, Mislivec A, Aliaga L, Altinok O, Bercellie A, Betancourt M, Bodek A, Bravar A, Brooks WK, Budd H, Butkevich A, Carneiro MF, Castromonte CM, Christy ME, Chvojka J, da Motta H, Devan J, Dytman SA, Díaz GA, Eberly B, Felix J, Fields L, Fine R, Fiorentini GA, Gallagher H, Gomez A, Gran R, Harris DA, Hurtado K, Kleykamp J, Kordosky M, Le T, Maher E, Manly S, Mann WA, Marshall CM, Martinez Caicedo DA, McFarland KS, McGivern CL, McGowan AM, Messerly B, Miller J, Morfín JG, Mousseau J, Muhlbeier T, Naples D, Nelson JK, Norrick A, Osta J, Palomino JL, Paolone V, Park J, Patrick CE, Perdue GN, Ransome RD, Ray H, Ren L, Rodrigues PA, Ruterbories D, Schellman H, Schmitz DW, Snider FD, Solano Salinas CJ, Tagg N, Tice BG, Valencia E, Walton T, Wolcott J, Wospakrik M, Zavala G, Zhang D, and Ziemer BP

Abstract

Neutrino-induced coherent charged pion production on nuclei νμA→μ(±)π(∓)A is a rare, inelastic interaction in which a small squared four-momentum |t| is transferred to the recoil nucleus, leaving it intact in the reaction. In the scintillator tracker of MINERvA, we remove events with evidence of particles from nuclear breakup and reconstruct |t| from the final-state pion and muon. We select low |t| events to isolate a sample rich in coherent candidates. By selecting low |t| events, we produce a model-independent measurement of the differential cross section for coherent scattering of neutrinos and antineutrinos on carbon. We find poor agreement with the predicted kinematics in neutrino generators used by current oscillation experiments.

Published
2014
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11. Measurement of ratios of νμ charged-current cross sections on C, Fe, and Pb to CH at neutrino energies 2-20 GeV.

Author

Tice BG, Datta M, Mousseau J, Aliaga L, Altinok O, Barrios Sazo MG, Betancourt M, Bodek A, Bravar A, Brooks WK, Budd H, Bustamante MJ, Butkevich A, Martinez Caicedo DA, Castromonte CM, Christy ME, Chvojka J, da Motta H, Devan J, Dytman SA, Díaz GA, Eberly B, Felix J, Fields L, Fiorentini GA, Gago AM, Gallagher H, Gran R, Harris DA, Higuera A, Hurtado K, Jerkins M, Kafka T, Kordosky M, Kulagin SA, Le T, Maggi G, Maher E, Manly S, Mann WA, Marshall CM, Martin Mari C, McFarland KS, McGivern CL, McGowan AM, Miller J, Mislivec A, Morfín JG, Muhlbeier T, Naples D, Nelson JK, Norrick A, Osta J, Palomino JL, Paolone V, Park J, Patrick CE, Perdue GN, Rakotondravohitra L, Ransome RD, Ray H, Ren L, Rodrigues PA, Savage DG, Schellman H, Schmitz DW, Simon C, Snider FD, Solano Salinas CJ, Tagg N, Valencia E, Velásquez JP, Walton T, Wolcott J, Zavala G, Zhang D, and Ziemer BP

Abstract

We present measurements of ν(μ) charged-current cross section ratios on carbon, iron, and lead relative to a scintillator (CH) using the fine-grained MINERvA detector exposed to the NuMI neutrino beam at Fermilab. The measurements utilize events of energies 2

Published
2014
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12. Separated response function ratios in exclusive, forward π(±) electroproduction.

Author

Huber GM, Blok HP, Butuceanu C, Gaskell D, Horn T, Mack DJ, Abbott D, Aniol K, Anklin H, Armstrong C, Arrington J, Assamagan K, Avery S, Baker OK, Barrett B, Beise EJ, Bochna C, Boeglin W, Brash EJ, Breuer H, Chang CC, Chant N, Christy ME, Dunne J, Eden T, Ent R, Fenker H, Gibson EF, Gilman R, Gustafsson K, Hinton W, Holt RJ, Jackson H, Jin S, Jones MK, Keppel CE, Kim PH, Kim W, King PM, Klein A, Koltenuk D, Kovaltchouk V, Liang M, Liu J, Lolos GJ, Lung A, Margaziotis DJ, Markowitz P, Matsumura A, McKee D, Meekins D, Mitchell J, Miyoshi T, Mkrtchyan H, Mueller B, Niculescu G, Niculescu I, Okayasu Y, Pentchev L, Perdrisat C, Pitz D, Potterveld D, Punjabi V, Qin LM, Reimer PE, Reinhold J, Roche J, Roos PG, Sarty A, Shin IK, Smith GR, Stepanyan S, Tang LG, Tadevosyan V, Tvaskis V, van der Meer RL, Vansyoc K, Van Westrum D, Vidakovic S, Volmer J, Vulcan W, Warren G, Wood SA, Xu C, Yan C, Zhao WX, Zheng X, and Zihlmann B

Abstract

The study of exclusive π(±) electroproduction on the nucleon, including separation of the various structure functions, is of interest for a number of reasons. The ratio RL=σL(π-)/σL(π+) is sensitive to isoscalar contamination to the dominant isovector pion exchange amplitude, which is the basis for the determination of the charged pion form factor from electroproduction data. A change in the value of RT=σT(π-)/σT(π+) from unity at small -t, to 1/4 at large -t, would suggest a transition from coupling to a (virtual) pion to coupling to individual quarks. Furthermore, the mentioned ratios may show an earlier approach to perturbative QCD than the individual cross sections. We have performed the first complete separation of the four unpolarized electromagnetic structure functions above the dominant resonances in forward, exclusive π(±) electroproduction on the deuteron at central Q(2) values of 0.6, 1.0, 1.6  GeV(2) at W=1.95  GeV, and Q(2)=2.45  GeV(2) at W=2.22  GeV. Here, we present the L and T cross sections, with emphasis on RL and RT, and compare them with theoretical calculations. Results for the separated ratio RL indicate dominance of the pion-pole diagram at low -t, while results for RT are consistent with a transition between pion knockout and quark knockout mechanisms.

Published
2014
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13. Measurement of muon neutrino quasielastic scattering on a hydrocarbon target at Eν ~ 3.5 GeV.

Author

Fiorentini GA, Schmitz DW, Rodrigues PA, Aliaga L, Altinok O, Baldin B, Baumbaugh A, Bodek A, Boehnlein D, Boyd S, Bradford R, Brooks WK, Budd H, Butkevich A, Martinez Caicedo DA, Castromonte CM, Christy ME, Chung H, Chvojka J, Clark M, da Motta H, Damiani DS, Danko I, Datta M, Day M, DeMaat R, Devan J, Draeger E, Dytman SA, Díaz GA, Eberly B, Edmondson DA, Felix J, Fields L, Fitzpatrick T, Gago AM, Gallagher H, George CA, Gielata JA, Gingu C, Gobbi B, Gran R, Grossman N, Hanson J, Harris DA, Heaton J, Higuera A, Howley IJ, Hurtado K, Jerkins M, Kafka T, Kaisen J, Kanter MO, Keppel CE, Kilmer J, Kordosky M, Krajeski AH, Kulagin SA, Le T, Lee H, Leister AG, Locke G, Maggi G, Maher E, Manly S, Mann WA, Marshall CM, McFarland KS, McGivern CL, McGowan AM, Mislivec A, Morfín JG, Mousseau J, Naples D, Nelson JK, Niculescu G, Niculescu I, Ochoa N, O'Connor CD, Olsen J, Osmanov B, Osta J, Palomino JL, Paolone V, Park J, Patrick CE, Perdue GN, Peña C, Rakotondravohitra L, Ransome RD, Ray H, Ren L, Rude C, Sassin KE, Schellman H, Schneider RM, Schulte EC, Simon C, Snider FD, Snyder MC, Sobczyk JT, Solano Salinas CJ, Tagg N, Tan W, Tice BG, Tzanakos G, Velásquez JP, Walding J, Walton T, Wolcott J, Wolthuis BA, Woodward N, Zavala G, Zeng HB, Zhang D, Zhu LY, and Ziemer BP

Abstract

We report a study of ν(μ) charged-current quasielastic events in the segmented scintillator inner tracker of the MINERvA experiment running in the NuMI neutrino beam at Fermilab. The events were selected by requiring a μ- and low calorimetric recoil energy separated from the interaction vertex. We measure the flux-averaged differential cross section, dσ/dQ², and study the low energy particle content of the final state. Deviations are found between the measured dσ/dQ² and the expectations of a model of independent nucleons in a relativistic Fermi gas. We also observe an excess of energy near the vertex consistent with multiple protons in the final state.

Published
2013
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14. Measurement of muon antineutrino quasielastic scattering on a hydrocarbon target at Eν ~ 3.5 GeV.

Author

Fields L, Chvojka J, Aliaga L, Altinok O, Baldin B, Baumbaugh A, Bodek A, Boehnlein D, Boyd S, Bradford R, Brooks WK, Budd H, Butkevich A, Martinez Caicedo DA, Castromonte CM, Christy ME, Chung H, Clark M, da Motta H, Damiani DS, Danko I, Datta M, Day M, DeMaat R, Devan J, Draeger E, Dytman SA, Díaz GA, Eberly B, Edmondson DA, Felix J, Fitzpatrick T, Fiorentini GA, Gago AM, Gallagher H, George CA, Gielata JA, Gingu C, Gobbi B, Gran R, Grossman N, Hanson J, Harris DA, Heaton J, Higuera A, Howley IJ, Hurtado K, Jerkins M, Kafka T, Kaisen J, Kanter MO, Keppel CE, Kilmer J, Kordosky M, Krajeski AH, Kulagin SA, Le T, Lee H, Leister AG, Locke G, Maggi G, Maher E, Manly S, Mann WA, Marshall CM, McFarland KS, McGivern CL, McGowan AM, Mislivec A, Morfín JG, Mousseau J, Naples D, Nelson JK, Niculescu G, Niculescu I, Ochoa N, O'Connor CD, Olsen J, Osmanov B, Osta J, Palomino JL, Paolone V, Park J, Patrick CE, Perdue GN, Peña C, Rakotondravohitra L, Ransome RD, Ray H, Ren L, Rodrigues PA, Rude C, Sassin KE, Schellman H, Schmitz DW, Schneider RM, Schulte EC, Simon C, Snider FD, Snyder MC, Sobczyk JT, Solano Salinas CJ, Tagg N, Tan W, Tice BG, Tzanakos G, Velásquez JP, Walding J, Walton T, Wolcott J, Wolthuis BA, Woodward N, Zavala G, Zeng HB, Zhang D, Zhu LY, and Ziemer BP

Abstract

We have isolated ν(μ) charged-current quasielastic (QE) interactions occurring in the segmented scintillator tracking region of the MINERvA detector running in the NuMI neutrino beam at Fermilab. We measure the flux-averaged differential cross section, dσ/dQ², and compare to several theoretical models of QE scattering. Good agreement is obtained with a model where the nucleon axial mass, M(A), is set to 0.99 GeV/c² but the nucleon vector form factors are modified to account for the observed enhancement, relative to the free nucleon case, of the cross section for the exchange of transversely polarized photons in electron-nucleus scattering. Our data at higher Q² favor this interpretation over an alternative in which the axial mass is increased.

Published
2013
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15. Moments of the longitudinal proton structure function FL from global data in the Q(2) range 0.75-45.0  (GeV/c)(2).

Author

Monaghan P, Accardi A, Christy ME, Keppel CE, Melnitchouk W, and Zhu L

Abstract

We present an extraction of the lowest three moments of the proton longitudinal structure function FL from world data between Q(2)=0.75 and 45  (GeV/c)(2). The availability of new FL data at low Bjorken x from HERA and at large x from Jefferson Lab allows the first determination of these moments over a large Q(2) range, relatively free from uncertainties associated with extrapolations into unmeasured regions. The moments are found to be underestimated by leading twist structure function parametrizations, especially for the higher moments, suggesting either the presence of significant higher twist effects in FL and/or a larger gluon distribution at high x.

Published
2013
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16. Polarization components in π0 photoproduction at photon energies up to 5.6 GeV.

Author

Luo W, Brash EJ, Gilman R, Jones MK, Meziane M, Pentchev L, Perdrisat CF, Puckett AJ, Punjabi V, Wesselmann FR, Ahmidouch A, Albayrak I, Aniol KA, Arrington J, Asaturyan A, Ates O, Baghdasaryan H, Benmokhtar F, Bertozzi W, Bimbot L, Bosted P, Boeglin W, Butuceanu C, Carter P, Chernenko S, Christy ME, Commisso M, Cornejo JC, Covrig S, Danagoulian S, Daniel A, Davidenko A, Day D, Dhamija S, Dutta D, Ent R, Frullani S, Fenker H, Frlez E, Garibaldi F, Gaskell D, Gilad S, Goncharenko Y, Hafidi K, Hamilton D, Higinbotham DW, Hinton W, Horn T, Hu B, Huang J, Huber GM, Jensen E, Kang H, Keppel C, Khandaker M, King P, Kirillov D, Kohl M, Kravtsov V, Kumbartzki G, Li Y, Mamyan V, Margaziotis DJ, Markowitz P, Marsh A, Matulenko Y, Maxwell J, Mbianda G, Meekins D, Melnik Y, Miller J, Mkrtchyan A, Mkrtchyan H, Moffit B, Moreno O, Mulholland J, Narayan A, Nuruzzaman, Nedev S, Piasetzky E, Pierce W, Piskunov NM, Prok Y, Ransome RD, Razin DS, Reimer PE, Reinhold J, Rondon O, Shabestari M, Shahinyan A, Shestermanov K, Širca S, Sitnik I, Smykov L, Smith G, Solovyev L, Solvignon P, Strakovsky II, Subedi R, Suleiman R, Tomasi-Gustafsson E, Vasiliev A, Veilleux M, Wood S, Ye Z, Zanevsky Y, Zhang X, Zhang Y, Zheng X, and Zhu L

Abstract

We present new data for the polarization observables of the final state proton in the (1)H(γ,p)π(0) reaction. These data can be used to test predictions based on hadron helicity conservation and perturbative QCD. These data have both small statistical and systematic uncertainties and were obtained with beam energies between 1.8 and 5.6 GeV and for π(0) scattering angles larger than 75° in the center-of-mass frame. The data extend the polarization measurements database for neutral pion photoproduction up to E(γ)=5.6 GeV. The results show a nonzero induced polarization above the resonance region. The polarization transfer components vary rapidly with the photon energy and π(0) scattering angle in the center-of-mass frame. This indicates that hadron helicity conservation does not hold and that the perturbative QCD limit is still not reached in the energy regime of this experiment.

Published
2012
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17. Measurement of the neutron F2 structure function via spectator tagging with CLAS.

Author

Baillie N, Tkachenko S, Zhang J, Bosted P, Bültmann S, Christy ME, Fenker H, Griffioen KA, Keppel CE, Kuhn SE, Melnitchouk W, Tvaskis V, Adhikari KP, Adikaram D, Aghasyan M, Amaryan MJ, Anghinolfi M, Arrington J, Avakian H, Baghdasaryan H, Battaglieri M, Biselli AS, Branford D, Briscoe WJ, Brooks WK, Burkert VD, Carman DS, Celentano A, Chandavar S, Charles G, Cole PL, Contalbrigo M, Crede V, D'Angelo A, Daniel A, Dashyan N, De Vita R, De Sanctis E, Deur A, Dey B, Djalali C, Dodge G, Domingo J, Doughty D, Dupre R, Dutta D, Ent R, Egiyan H, El Alaoui A, El Fassi L, Elouadrhiri L, Eugenio P, Fedotov G, Fegan S, Fradi A, Gabrielyan MY, Gevorgyan N, Gilfoyle GP, Giovanetti KL, Girod FX, Gohn W, Golovatch E, Gothe RW, Graham L, Guegan B, Guidal M, Guler N, Guo L, Hafidi K, Heddle D, Hicks K, Holtrop M, Hungerford E, Hyde CE, Ilieva Y, Ireland DG, Ispiryan M, Isupov EL, Jawalkar SS, Jo HS, Kalantarians N, Khandaker M, Khetarpal P, Kim A, Kim W, King PM, Klein A, Klein FJ, Klimenko A, Kubarovsky V, Kuleshov SV, Kvaltine ND, Livingston K, Lu HY, MacGregor IJ, Mao Y, Markov N, McKinnon B, Mineeva T, Morrison B, Moutarde H, Munevar E, Nadel-Turonski P, Ni A, Niccolai S, Niculescu I, Niculescu G, Osipenko M, Ostrovidov AI, Pappalardo L, Park K, Park S, Pasyuk E, Anefalos Pereira S, Pisano S, Pozdniakov S, Price JW, Procureur S, Prok Y, Protopopescu D, Raue BA, Ricco G, Rimal D, Ripani M, Rosner G, Rossi P, Sabatié F, Saini MS, Salgado C, Schott D, Schumacher RA, Seder E, Sharabian YG, Sober DI, Sokhan D, Stepanyan S, Stepanyan SS, Stoler P, Strauch S, Taiuti M, Tang W, Ungaro M, Vineyard MF, Voutier E, Watts DP, Weinstein LB, Weygand DP, Wood MH, Zana L, and Zhao B

Abstract

We report on the first measurement of the F(2) structure function of the neutron from the semi-inclusive scattering of electrons from deuterium, with low-momentum protons detected in the backward hemisphere. Restricting the momentum of the spectator protons to ≲100 MeV/c and their angles to ≳100° relative to the momentum transfer allows an interpretation of the process in terms of scattering from nearly on-shell neutrons. The F(2)(n) data collected cover the nucleon-resonance and deep-inelastic regions over a wide range of Bjorken x for 0.65

Published
2012
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18. New measurements of high-momentum nucleons and short-range structures in nuclei.

Author

Fomin N, Arrington J, Asaturyan R, Benmokhtar F, Boeglin W, Bosted P, Bruell A, Bukhari MH, Christy ME, Chudakov E, Clasie B, Connell SH, Dalton MM, Daniel A, Day DB, Dutta D, Ent R, El Fassi L, Fenker H, Filippone BW, Garrow K, Gaskell D, Hill C, Holt RJ, Horn T, Jones MK, Jourdan J, Kalantarians N, Keppel CE, Kiselev D, Kotulla M, Lindgren R, Lung AF, Malace S, Markowitz P, McKee P, Meekins DG, Mkrtchyan H, Navasardyan T, Niculescu G, Opper AK, Perdrisat C, Potterveld DH, Punjabi V, Qian X, Reimer PE, Roche J, Rodriguez VM, Rondon O, Schulte E, Seely J, Segbefia E, Slifer K, Smith GR, Solvignon P, Tadevosyan V, Tajima S, Tang L, Testa G, Trojer R, Tvaskis V, Vulcan WF, Wasko C, Wesselmann FR, Wood SA, Wright J, and Zheng X

Abstract

We present new measurements of electron scattering from high-momentum nucleons in nuclei. These data allow an improved determination of the strength of two-nucleon correlations for several nuclei, including light nuclei where clustering effects can, for the first time, be examined. The data also include the kinematic region where three-nucleon correlations are expected to dominate.

Published
2012
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19. Precise extraction of the induced polarization in the 4He(e,e'p)3H reaction.

Author

Malace SP, Paolone M, Strauch S, Albayrak I, Arrington J, Berman BL, Brash EJ, Briscoe B, Camsonne A, Chen JP, Christy ME, Chudakov E, Cisbani E, Craver B, Cusanno F, Ent R, Garibaldi F, Gilman R, Glamazdin O, Glister J, Higinbotham DW, Hyde-Wright CE, Ilieva Y, de Jager CW, Jiang X, Jones MK, Keppel CE, Khrosinkova E, Kuchina E, Kumbartzki G, Lee B, Lindgren R, Margaziotis DJ, Meekins D, Michaels R, Park K, Pentchev L, Perdrisat CF, Piasetzky E, Punjabi VA, Puckett AJ, Qian X, Qiang Y, Ransome RD, Saha A, Sarty AJ, Schulte E, Solvignon P, Subedi RR, Tang L, Tedeschi D, Tvaskis V, Udias JM, Ulmer PE, Vignote JR, Wesselmann FR, Wojtsekhowski B, and Zhan X

Abstract

We measured with unprecedented precision the induced polarization P(y) in (4)He(e,e'p)(3)H at Q(2)=0.8 and 1.3  (GeV/c)(2). The induced polarization is indicative of reaction-mechanism effects beyond the impulse approximation. Our results are in agreement with a relativistic distorted-wave impulse approximation calculation but are overestimated by a calculation with strong charge-exchange effects. Our data are used to constrain the strength of the spin-independent charge-exchange term in the latter calculation.

Published
2011
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20. Scaling of the F2 structure function in nuclei and quark distributions at x>1.

Author

Fomin N, Arrington J, Day DB, Gaskell D, Daniel A, Seely J, Asaturyan R, Benmokhtar F, Boeglin W, Boillat B, Bosted P, Bruell A, Bukhari MH, Christy ME, Chudakov E, Clasie B, Connell SH, Dalton MM, Dutta D, Ent R, El Fassi L, Fenker H, Filippone BW, Garrow K, Hill C, Holt RJ, Horn T, Jones MK, Jourdan J, Kalantarians N, Keppel CE, Kiselev D, Kotulla M, Lindgren R, Lung AF, Malace S, Markowitz P, McKee P, Meekins DG, Miyoshi T, Mkrtchyan H, Navasardyan T, Niculescu G, Okayasu Y, Opper AK, Perdrisat C, Potterveld DH, Punjabi V, Qian X, Reimer PE, Roche J, Rodriguez VM, Rondon O, Schulte E, Segbefia E, Slifer K, Smith GR, Solvignon P, Tadevosyan V, Tajima S, Tang L, Testa G, Trojer R, Tvaskis V, Vulcan WF, Wasko C, Wesselmann FR, Wood SA, Wright J, and Zheng X

Abstract

We present new data on electron scattering from a range of nuclei taken in Hall C at Jefferson Lab. For heavy nuclei, we observe a rapid falloff in the cross section for x>1, which is sensitive to short-range contributions to the nuclear wave function, and in deep inelastic scattering corresponds to probing extremely high momentum quarks. This result agrees with higher energy muon scattering measurements, but is in sharp contrast to neutrino scattering measurements which suggested a dramatic enhancement in the distribution of the "superfast" quarks probed at x>1. The falloff at x>1 is noticeably stronger in 2H and 3He, but nearly identical for all heavier nuclei.

Published
2010
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21. Probing quark-gluon interactions with transverse polarized scattering.

Author

Slifer K, Rondón OA, Aghalaryan A, Ahmidouch A, Asaturyan R, Bloch F, Boeglin W, Bosted P, Carasco C, Carlini R, Cha J, Chen JP, Christy ME, Cole L, Coman L, Crabb D, Danagoulian S, Day D, Dunne J, Elaasar M, Ent R, Fenker H, Frlez E, Gaskell D, Gan L, Gomez J, Hu B, Jourdan J, Jones MK, Keith C, Keppel CE, Khandaker M, Klein A, Kramer L, Liang Y, Lichtenstadt J, Lindgren R, Mack D, McKee P, McNulty D, Meekins D, Mkrtchyan H, Nasseripour R, Niculescu I, Normand K, Norum B, Pocanic D, Prok Y, Raue B, Reinhold J, Roche J, Kiselev D, Savvinov N, Sawatzky B, Seely M, Sick I, Smith C, Smith G, Stepanyan S, Tang L, Tajima S, Testa G, Vulcan W, Wang K, Warren G, Wesselmann FR, Wood S, Yan C, Yuan L, Yun J, Zeier M, and Zhu H

Abstract

We have extracted QCD matrix elements from our data on doubly polarized inelastic scattering of electrons on nuclei. We find the higher twist matrix element d˜2, which arises strictly from quark-gluon interactions, to be unambiguously nonzero. The data also reveal an isospin dependence of higher twist effects if we assume that the Burkhardt-Cottingham sum rule is valid. The fundamental Bjorken sum rule obtained from the a0 matrix element is satisfied at our low momentum transfer.

Published
2010
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22. Polarization transfer in the 4He(e,e'p)3H reaction at Q2=0.8 and 1.3 (GeV/c)2.

Author

Paolone M, Malace SP, Strauch S, Albayrak I, Arrington J, Berman BL, Brash EJ, Briscoe B, Camsonne A, Chen JP, Christy ME, Chudakov E, Cisbani E, Craver B, Cusanno F, Ent R, Garibaldi F, Gilman R, Glamazdin O, Glister J, Higinbotham DW, Hyde-Wright CE, Ilieva Y, de Jager CW, Jiang X, Jones MK, Keppel CE, Khrosinkova E, Kuchina E, Kumbartzki G, Lee B, Lindgren R, Margaziotis DJ, Meekins D, Michaels R, Park K, Pentchev L, Perdrisat CF, Piasetzky E, Punjabi VA, Puckett AJ, Qian X, Qiang Y, Ransome RD, Saha A, Sarty AJ, Schulte E, Solvignon P, Subedi RR, Tang L, Tedeschi D, Tvaskis V, Udias JM, Ulmer PE, Vignote JR, Wesselmann FR, Wojtsekhowski B, and Zhan X

Abstract

Proton recoil polarization was measured in the quasielastic 4He(e,e'p)3H reaction at Q{2}=0.8 and 1.3  (GeV/c){2} with unprecedented precision. The polarization-transfer coefficients are found to differ from those of the 1H(e,e'p) reaction, contradicting a relativistic distorted-wave approximation and favoring either the inclusion of medium-modified proton form factors predicted by the quark-meson coupling model or a spin-dependent charge-exchange final-state interaction. For the first time, the polarization-transfer ratio is studied as a function of the virtuality of the proton.

Published
2010
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23. New measurements of the European Muon Collaboration effect in very light nuclei.

Author

Seely J, Daniel A, Gaskell D, Arrington J, Fomin N, Solvignon P, Asaturyan R, Benmokhtar F, Boeglin W, Boillat B, Bosted P, Bruell A, Bukhari MH, Christy ME, Clasie B, Connell S, Dalton MM, Day D, Dunne J, Dutta D, El Fassi L, Ent R, Fenker H, Filippone BW, Gao H, Hill C, Holt RJ, Horn T, Hungerford E, Jones MK, Jourdan J, Kalantarians N, Keppel CE, Kiselev D, Kotulla M, Lee C, Lung AF, Malace S, Meekins DG, Mertens T, Mkrtchyan H, Navasardyan T, Niculescu G, Niculescu I, Nomura H, Okayasu Y, Opper AK, Perdrisat C, Potterveld DH, Punjabi V, Qian X, Reimer PE, Roche J, Rodriguez VM, Rondon O, Schulte E, Segbefia E, Slifer K, Smith GR, Tadevosyan V, Tajima S, Tang L, Testa G, Trojer R, Tvaskis V, Vulcan WF, Wesselmann FR, Wood SA, Wright J, Yuan L, and Zheng X

Abstract

New Jefferson Lab data are presented on the nuclear dependence of the inclusive cross section from (2)H, (3)He, (4)He, (9)Be and (12)C for 0.3 < x < 0.9, Q(2) approximately 3-6 GeV(2). These data represent the first measurement of the EMC effect for (3)He at large x and a significant improvement for (4)He. The data do not support previous A-dependent or density-dependent fits to the EMC effect and suggest that the nuclear dependence of the quark distributions may depend on the local nuclear environment.

Published
2009
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24. Measurement of nuclear transparency for the A(e,e'pi+) reaction.

Author

Clasie B, Qian X, Arrington J, Asaturyan R, Benmokhtar F, Boeglin W, Bosted P, Bruell A, Christy ME, Chudakov E, Cosyn W, Dalton MM, Daniel A, Day D, Dutta D, El Fassi L, Ent R, Fenker HC, Ferrer J, Fomin N, Gao H, Garrow K, Gaskell D, Gray C, Horn T, Huber GM, Jones MK, Kalantarians N, Keppel CE, Kramer K, Larson A, Li Y, Liang Y, Lung AF, Malace S, Markowitz P, Matsumura A, Meekins DG, Mertens T, Miller GA, Miyoshi T, Mkrtchyan H, Monson R, Navasardyan T, Niculescu G, Niculescu I, Okayasu Y, Opper AK, Perdrisat C, Punjabi V, Rauf AW, Rodriquez VM, Rohe D, Ryckebusch J, Seely J, Segbefia E, Smith GR, Strikman M, Sumihama M, Tadevosyan V, Tang L, Tvaskis V, Villano A, Vulcan WF, Wesselmann FR, Wood SA, Yuan L, and Zheng XC

Abstract

We have measured the nuclear transparency of the A(e,e'pi+) process in 2H, 12C, 27Al, 63Cu, and 197Au targets. These measurements were performed at the Jefferson Laboratory over a four momentum transfer squared range Q2=1.1 to 4.7 (GeV/c)2. The nuclear transparency was extracted as the super-ratio of (sigmaA/sigmaH) from data to a model of pion-electroproduction from nuclei without pi-N final-state interactions. The Q2 and atomic number dependence of the nuclear transparency both show deviations from traditional nuclear physics expectations and are consistent with calculations that include the quantum chromodynamical phenomenon of color transparency.

Published
2007
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25. Longitudinal-transverse separations of deep-inelastic structure functions at low Q2 for hydrogen and deuterium.

Author

Tvaskis V, Christy ME, Arrington J, Asaturyan R, Baker OK, Blok HP, Bosted P, Boswell M, Bruell A, Cochran A, Cole L, Crowder J, Dunne J, Ent R, Fenker HC, Filippone BW, Garrow K, Gasparian A, Gomez J, Jackson HE, Keppel CE, Kinney E, Lapikás L, Liang Y, Lorenzon W, Lung A, Mack DJ, Martin JW, McIlhany K, Meekins D, Milner RG, Mitchell JH, Mkrtchyan H, Moreland B, Nazaryan V, Niculescu I, Opper A, Piercey RB, Potterveld DH, Rose B, Sato Y, Seo W, Smith G, Spurlock K, van der Steenhoven G, Stepanyan S, Tadevosian V, Uzzle A, Vulcan WF, Wood SA, Zihlmann B, and Ziskin V

Abstract

We report on a study of the longitudinal to transverse cross section ratio, R=sigmaL/sigmaT, at low values of x and Q2, as determined from inclusive inelastic electron-hydrogen and electron-deuterium scattering data from Jefferson Laboratory Hall C spanning the four-momentum transfer range 0.06

Published
2007
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26. Proton spin structure in the resonance region.

Author

Wesselmann FR, Slifer K, Tajima S, Aghalaryan A, Ahmidouch A, Asaturyan R, Bloch F, Boeglin W, Bosted P, Carasco C, Carlini R, Cha J, Chen JP, Christy ME, Cole L, Coman L, Crabb D, Danagoulian S, Day D, Dunne J, Elaasar M, Ent R, Fenker H, Frlez E, Gan L, Gaskell D, Gomez J, Hu B, Jones MK, Jourdan J, Keith C, Keppel CE, Khandaker M, Klein A, Kramer L, Liang Y, Lichtenstadt J, Lindgren R, Mack D, McKee P, McNulty D, Meekins D, Mkrtchyan H, Nasseripour R, Niculescu I, Normand K, Norum B, Pocanic D, Prok Y, Raue B, Reinhold J, Roche J, Rohe D, Rondón OA, Savvinov N, Sawatzky B, Seely M, Sick I, Smith C, Smith G, Stepanyan S, Tang L, Testa G, Vulcan W, Wang K, Warren G, Wood S, Yan C, Yuan L, Yun J, Zeier M, and Zhu H

Abstract

We have examined the spin structure of the proton in the region of the nucleon resonances (1.085 GeV

Published
2007
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27. Onset of quark-hadron duality in pion electroproduction.

Author

Navasardyan T, Adams GS, Ahmidouch A, Angelescu T, Arrington J, Asaturyan R, Baker OK, Benmouna N, Bertoncini C, Blok HP, Boeglin WU, Bosted PE, Breuer H, Christy ME, Connell SH, Cui Y, Dalton MM, Danagoulian S, Day D, Dodario T, Dunne JA, Dutta D, El Khayari N, Ent R, Fenker HC, Frolov VV, Gan L, Gaskell D, Hafidi K, Hinton W, Holt RJ, Horn T, Huber GM, Hungerford E, Jiang X, Jones M, Joo K, Kalantarians N, Kelly JJ, Keppel CE, Kubarovski V, Li Y, Liang Y, Malace S, Markowitz P, McGrath E, McKee P, Meekins DG, Mkrtchyan H, Moziak B, Niculescu G, Niculescu I, Opper AK, Ostapenko T, Reimer P, Reinhold J, Roche J, Rock SE, Schulte E, Segbefia E, Smith C, Smith GR, Stoler P, Tadevosyan V, Tang L, Ungaro M, Uzzle A, Vidakovic S, Villano A, Vulcan WF, Wang M, Warren G, Wesselmann F, Wojtsekhowski B, Wood SA, Xu C, Yuan L, Zheng X, and Zhu H

Abstract

A large data set of charged-pion (pi+/-) electroproduction from both hydrogen and deuterium targets has been obtained spanning the low-energy residual-mass region. These data conclusively show the onset of the quark-hadron duality phenomenon, as predicted for high-energy hadron electroproduction. We construct several ratios from these data to exhibit the relation of this phenomenon to the high-energy factorization ansatz of electron-quark scattering and subsequent quark-->pion production mechanisms.

Published
2007
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28. Determination of the pion charge form factor at Q2=1.60 and 2.45 (GeV/c)2.

Author

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, and Zheng X

Abstract

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.

Published
2006
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29. Precision Rosenbluth measurement of the proton elastic form factors.

Author

Qattan IA, Arrington J, Segel RE, Zheng X, Aniol K, Baker OK, Beams R, Brash EJ, Calarco J, Camsonne A, Chen JP, Christy ME, Dutta D, Ent R, Frullani S, Gaskell D, Gayou O, Gilman R, Glashausser C, Hafidi K, Hansen JO, Higinbotham DW, Hinton W, Holt RJ, Huber GM, Ibrahim H, Jisonna L, Jones MK, Keppel CE, Kinney E, Kumbartzki GJ, Lung A, Margaziotis DJ, McCormick K, Meekins D, Michaels R, Monaghan P, Moussiegt P, Pentchev L, Perdrisat C, Punjabi V, Ransome R, Reinhold J, Reitz B, Saha A, Sarty A, Schulte EC, Slifer K, Solvignon P, Sulkosky V, Wijesooriya K, and Zeidman B

Abstract

We report the results of a new Rosenbluth measurement of the proton electromagnetic form factors at Q2 values of 2.64, 3.20, and 4.10 GeV2. Cross sections were determined by detecting the recoiling proton, in contrast to previous measurements which detected the scattered electron. Cross sections were determined to 3%, with relative uncertainties below 1%. The ratio mu(p)G(E)/G(M) was determined to 4%-8% and showed mu(p)G(E)/G(M) approximately 1. These results are consistent with, and much more precise than, previous Rosenbluth extractions. They are inconsistent with recent polarization transfer measurements of similar precision, implying a systematic difference between the techniques.

Published
2005
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30. Polarization transfer in the 4He(e-->,e'p-->)3H reaction up to Q2=2.6 (GeV/c)2.

Author

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, Meekins D, Michaels R, Mitchell JH, Nanda SK, Nappa J, Perdrisat CF, Punjabi VA, Ransome RD, Roché R, Rosner G, Rvachev M, Sabatie F, Saha A, Sarty A, Udias JM, Ulmer PE, Urciuoli GM, van den Brand JF, Vignote JR, Watts DP, Weinstein LB, Wijesooriya K, and Wojtsekhowski B

Abstract

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.

Published
2003
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31. Observation of double radiative capture on pionic hydrogen.

Author

Tripathi S, Armstrong DS, Christy ME, Clark JH, Gorringe TP, Hasinoff MD, Kovash MA, Wright DH, and Zołnierczuk PA

Abstract

We report the first observation of double radiative capture on pionic hydrogen. The experiment was conducted at the TRIUMF cyclotron using the RMC spectrometer and detected gamma-ray coincidences following pi(-) stops in liquid hydrogen. We found the branching ratio for double radiative capture to be [3.05+/-0.27(stat)+/-0.31(syst)]x10(-5). The measured branching ratio and angle-energy distributions support the theoretical prediction of a dominant contribution from the pipi-->gammagamma annihilation mechanism.

Published
2002
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