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1. Deep exclusive electroproduction of $\pi^0$ at high $Q^2$ in the quark valence regime

Author

The Jefferson Lab Hall A Collaboration, Dlamini, M., Karki, B., Ali, S. F., Lin, P-J., Georges, F., Ko, H-S, Israel, N., Rashad, M. N. H., 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., Gayoso, C. Ayerbe, 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, M. E., Cisbani, E., Clary, B., Cohen, E., Compton, N., Cornejo, J. C., Dusa, S. Covrig, 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, V. M., Gu, C., Hague, T., Hamad, G., Hamilton, D., Hamilton, K., Hansen, O., Hauenstein, F., Henry, W., Higinbotham, D. W., Holmstrom, T., Horn, T., Huang, Y., Huber, G. M., Hyde, C., Ibrahim, H., Jen, C-M., Jin, K., Jones, M., Kabir, A., Keppel, C., Khachatryan, V., King, P. M., Li, S., Li, W., Liu, J., Liu, H., Liyanage, A., Magee, J., Malace, S., Mammei, J., Markowitz, P., McClellan, E., Meddi, F., Meekins, D., Mesik, K., Michaels, R., Mkrtchyan, A., Montgomery, R., Camacho, C. Munoz, Myers, L. S., Nadel-Turonski, P., Nazeer, S. J., Nelyubin, V., Nguyen, D., Nuruzzaman, N., Nycz, M., Obretch, O. F., Ou, L., Palatchi, C., Pandey, B., Park, S., Park, K., Peng, C., Pomatsalyuk, R., Pooser, E., Puckett, A. J. R., Punjabi, V., Quinn, B., Rahman, S., Reimer, P. E., Roche, J., Sapkota, I., Sarty, A., Sawatzky, B., Saylor, N. H., Schmookler, B., Shabestari, M. H., Shahinyan, A., Sirca, S., Smith, G. R., Sooriyaarachchilage, S., Sparveris, N., Spies, R., Su, T., Subedi, A., Sulkosky, V., Sun, A., Thorne, L., Tian, Y., Ton, N., Tortorici, F., Trotta, R., Urciuoli, G. M., Voutier, E., Waidyawansa, B., Wang, Y., Wojtsekhowski, B., Wood, S., Yan, X., Ye, L., Ye, Z., Yero, C., Zhang, J., Zhao, Y., and Zhu, P.

Subjects
High Energy Physics - Experiment, Nuclear Experiment
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 $d\sigma_L/dt+\epsilon d\sigma_T/dt$, $d\sigma_{TT}/dt$, $d\sigma_{LT}/dt$ and $d\sigma_{LT'}/dt$ 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
2020
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2. High-resolution hypernuclear spectroscopy at Jefferson Lab, Hall A

Author

Jefferson Lab Hall A Collaboration, Garibaldi, F., Acha, A., Ambrozewicz, P., Aniol, K. A., Beturin, P., Benaoum, H., Benesch, J., Bertin, P. Y., Blomqvist, K. I., Boeglin, W. U., Breuer, H., Brindza, P., Bydzovsky, P., Camsonne, A., Chang, C. C., Chen, J. -P., Choi, Seonho, Chudakov, E. A., Cisbani, E., Colilli, S., Coman, L., Cusanno, F., Craver, B. J., De Cataldo, G., de Jager, C. W., De Leo, R., Deur, A. P., Ferdi, C., Feuerbach, R. J., Folts, E., Frullani, S., Gayou, O., Giuliani, F., Gomez, J., Gricia, M., Hansen, J. O., Hayes, D., Higinbotham, D. W., Holmstrom, T. K., Hyde, C. E., Ibrahim, H. F., Iodice, M., Jiang, X., Kaufman, L. J., Kino, K., Kross, B., Lagamba, L., LeRose, J. J., Lindgren, R. A., Lucentini, M., Margaziotis, D. J., Markowitz, P., Marrone, S., Meekins, D. G., Meziani, Z. E., McCormick, K., Michaels, R. W., Millener, D. J., Miyoshi, T., Moffit, B., Monaghan, P. A., Moteabbed, M., Camacho, C. Munoz, Nanda, S., Nappi, E., Nelyubin, V. V., Norum, B. E., Okasyasu, Y., Paschke, K. D., Perdrisat, C. F., Piasetzky, E., Punjabi, V. A., Qiang, Y., Raue, B., Reimer, P. E., Reinhold, J., Reitz, B., Roche, R. E., Rodriguez, V. M., Saha, A., Santavenere, F., Sarty, A. J., Segal, J., Shahinyan, A., Singh, J., Sirca, S., Snyder, R., Solvignon, P. H., Sotona, M., Subedi, R., Sulkosky, V. A., Suzuki, T., Ueno, H., Ulmer, P. E., Urciuoli, G. M., Voutier, E., Wojtsekhowski, B. B., Zheng, X., and Zorn, C.

Subjects
Nuclear Experiment, Nuclear Theory
Abstract

The experiment E94-107 in Hall A at Jefferson Lab started a systematic study of high resolution hypernuclear spectroscopy in the 0p-shell region of nuclei such as the hypernuclei produced in electroproduction on 9Be, 12C and 16O targets. In order to increase counting rates and provide unambiguous kaon identification two superconducting septum magnets and a ring-imaging Cherenkov detector were added to the Hall A standard equipment. The high-quality beam, the good spectrometers and the new experimental devices allowed us to obtain very good results. For the first time, measurable strength with sub-MeV energy resolution was observed for the core-excited states of Lambda 12B. A high-quality Lambda 16N hypernuclear spectrum was likewise obtained. A first measurement of the Lambda binding energy for Lambda 16N, calibrated against the elementary reaction on hydrogen, was obtained with high precision, 13.76 +/- 0.16 MeV. Similarly, the first Lambda 9Li hypernuclear spectrum shows general agreement with theory (distorted-wave impulse approximation with the SLA and BS3 electroproduction models and shell-model wave functions). Some disagreement exists with respect to the relative strength of the states making up the first multiplet. A Lambda separation energy of 8.36 MeV was obtained, in agreement with previous results. It has been shown that the electroproduction of hypernuclei can provide information complementary to that obtained with hadronic probes and the gamma-ray spectroscopy technique., Comment: 27 pages, 18 figures, submitted to Physical Review C

Published
2018
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3. Publisher's Note: JLab Measurements of the ^{3}He Form Factors at Large Momentum Transfers [Phys. Rev. Lett. 119, 162501 (2017)].

Author

Camsonne, A, Katramatou, AT, Olson, M, Acha, A, Allada, K, Anderson, BD, Arrington, J, Baldwin, A, Chen, J-P, Choi, S, Chudakov, E, Cisbani, E, Craver, B, Decowski, P, Dutta, C, Folts, E, Frullani, S, Garibaldi, F, Gilman, R, Gomez, J, Hahn, B, Hansen, J-O, Higinbotham, DW, Holmstrom, T, Huang, J, Iodice, M, Jiang, X, Kelleher, A, Khrosinkova, E, Kievsky, A, Kuchina, E, Kumbartzki, G, Lee, B, LeRose, JJ, Lindgren, RA, Lott, G, Lu, H, Marcucci, LE, Margaziotis, DJ, Markowitz, P, Marrone, S, Meekins, D, Meziani, Z-E, Michaels, R, Moffit, B, Norum, B, Petratos, GG, Puckett, A, Qian, X, Rondon, O, Saha, A, Sawatzky, B, Segal, J, Shabestari, M, Shahinyan, A, Solvignon, P, Sparveris, N, Subedi, RR, Suleiman, R, Sulkosky, V, Urciuoli, GM, Viviani, M, Wang, Y, Wojtsekhowski, BB, Yan, X, Yao, H, Zhang, W-M, Zheng, X, Zhu, L, and Jefferson Lab Hall A Collaboration

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

This corrects the article DOI: 10.1103/PhysRevLett.119.162501.

Published
2017

4. JLab Measurements of the ^{3}He Form Factors at Large Momentum Transfers.

Author

Camsonne, A, Katramatou, AT, Olson, M, Acha, A, Allada, K, Anderson, BD, Arrington, J, Baldwin, A, Chen, J-P, Choi, S, Chudakov, E, Cisbani, E, Craver, B, Decowski, P, Dutta, C, Folts, E, Frullani, S, Garibaldi, F, Gilman, R, Gomez, J, Hahn, B, Hansen, J-O, Higinbotham, DW, Holmstrom, T, Huang, J, Iodice, M, Jiang, X, Kelleher, A, Khrosinkova, E, Kievsky, A, Kuchina, E, Kumbartzki, G, Lee, B, LeRose, JJ, Lindgren, RA, Lott, G, Lu, H, Marcucci, LE, Margaziotis, DJ, Markowitz, P, Marrone, S, Meekins, D, Meziani, Z-E, Michaels, R, Moffit, B, Norum, B, Petratos, GG, Puckett, A, Qian, X, Rondon, O, Saha, A, Sawatzky, B, Segal, J, Shabestari, M, Shahinyan, A, Solvignon, P, Sparveris, N, Subedi, RR, Suleiman, R, Sulkosky, V, Urciuoli, GM, Viviani, M, Wang, Y, Wojtsekhowski, BB, Yan, X, Yao, H, Zhang, W-M, Zheng, X, Zhu, L, and Jefferson Lab Hall A Collaboration

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

The charge and magnetic form factors, F_{C} and F_{M}, respectively, of ^{3}He are extracted in the kinematic range 25  fm^{-2}≤Q^{2}≤61  fm^{-2} from elastic electron scattering by detecting ^{3}He recoil nuclei and scattered electrons in coincidence with the two High Resolution Spectrometers of the Hall A Facility at Jefferson Lab. The measurements find evidence for the existence of a second diffraction minimum for the magnetic form factor at Q^{2}=49.3  fm^{-2} and for the charge form factor at Q^{2}=62.0  fm^{-2}. Both minima are predicted to exist in the Q^{2} range accessible by this Jefferson Lab experiment. The data are in qualitative agreement with theoretical calculations based on realistic interactions and accurate methods to solve the three-body nuclear problem.

Published
2017

5. Double Spin Asymmetries of Inclusive Hadron Electroproductions from a Transversely Polarized $^3\rm{He}$ Target

Author

The Jefferson Lab Hall A Collaboration, Zhao, Y. X., Allada, K., Aniol, K., Annand, J. R. M., Averett, T., Benmokhtar, F., Bertozzi, W., Bradshaw, P. C., Bosted, P., Camsonne, A., Canan, M., Cates, G. D., Chen, C., Chen, J. -P., Chen, W., Chirapatpimol, K., Chudakov, E., Cisbani, E., Cornejo, J. C., Cusanno, F., Dalton, M., Deconinck, W., de Jager, C. W., De Leo, R., Deng, X., Deur, A., Ding, H., Dolph, P. A. M., Dutta, C., Dutta, D., Fassi, L. El, Frullani, S., Gao, H., Garibaldi, F., Gaskell, D., Gilad, S., Gilman, R., Glamazdin, O., Golge, S., Guo, L., Hamilton, D., Hansen, O., Higinbotham, D. W., Holmstrom, T., Huang, J., Huang, M., Ibrahim, H. F, Iodice, M., Jiang, X., Jin, G., Jones, M. K., Katich, J., Kelleher, A., Kim, W., Kolarkar, A., Korsch, W., LeRose, J. J., Li, X., Li, Y., Lindgren, R., Liyanage, N., Long, E., Lu, H. -J., Margaziotis, D. J., Markowitz, P., Marrone, S., McNulty, D., Meziani, Z. -E., Michaels, R., Moffit, B., Camacho, C. Muñoz, Nanda, S., Narayan, A., Nelyubin, V., Norum, B., Oh, Y., Osipenko, M., Parno, D., Peng, J. -C., Phillips, S. K., Posik, M., Puckett, A. J. R., Qian, X., Qiang, Y., Rakhman, A., Ransome, R., Riordan, S., Saha, A., Sawatzky, B., Schulte, E., Shahinyan, A., Shabestari, M. H., Širca, S., Stepanyan, S., Subedi, R., Sulkosky, V., Tang, L. -G., Tobias, W. A., Urciuoli, G. M., Vilardi, I., Wang, K., Wojtsekhowski, B., Wang, Y., Yan, X., Yao, H., Ye, Y., Ye, Z., Yuan, L., Zhan, X., Zhang, Y., Zhang, Y. -W., Zhao, B., Zheng, X., Zhu, L., Zhu, X., and Zong, X.

Subjects
Nuclear Experiment, High Energy Physics - Experiment, High Energy Physics - Phenomenology
Abstract

We report the measurement of beam-target double-spin asymmetries ($A_\text{LT}$) in the inclusive production of identified hadrons, $\vec{e}~$+$~^3\text{He}^{\uparrow}\rightarrow h+X$, using a longitudinally polarized 5.9 GeV electron beam and a transversely polarized $^3\rm{He}$ target. Hadrons ($\pi^{\pm}$, $K^{\pm}$ and proton) were detected at 16$^{\circ}$ with an average momentum $<$$P_h$$>$=2.35 GeV/c and a transverse momentum ($p_{T}$) coverage from 0.60 to 0.68 GeV/c. Asymmetries from the $^3\text{He}$ target were observed to be non-zero for $\pi^{\pm}$ production when the target was polarized transversely in the horizontal plane. The $\pi^{+}$ and $\pi^{-}$ asymmetries have opposite signs, analogous to the behavior of $A_\text{LT}$ in semi-inclusive deep-inelastic scattering., Comment: Published in PRC (92.015207), nuclear experiment, high-energy experiment

Published
2015
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6. Measurement of double-polarization asymmetries in the quasi-elastic $^3\vec{\mathrm{He}}(\vec{\mathrm{e}},\mathrm{e}'\mathrm{d})$ process

Author

The Jefferson Lab Hall A Collaboration, Mihovilovič, M., Jin, G., Long, E., Zhang, Y. -W., Allada, K., Anderson, B., Annand, J. R. M., Averett, T., Boeglin, W., Bradshaw, P., Camsonne, A., Canan, M., Cates, G. D., Chen, C., Chen, J. P., Chudakov, E., De Leo, R., Deng, X., Deltuva, A., Deur, A., Dutta, C., Fassi, L. El, Flay, D., Frullani, S., Garibaldi, F., Gao, H., Gilad, S., Gilman, R., Glamazdin, O., Golak, J., Golge, S., Gomez, J., Hansen, O., Higinbotham, D. W., Holmstrom, T., Huang, J., Ibrahim, H., de Jager, C. W., Jensen, E., Jiang, X., Jones, M., Kang, H., Katich, J., Khanal, H. P., Kievsky, A., King, P., Korsch, W., LeRose, J., Lindgren, R., Lu, H. -J., Luo, W., Marcucci, L. E., Markowitz, P., Meziane, M., Michaels, R., Moffit, B., Monaghan, P., Muangma, N., Nanda, S., Norum, B. E., Pan, K., Parno, D., Piasetzky, E., Posik, M., Punjabi, V., Puckett, A. J. R., Qian, X., Qiang, Y., Qui, X., Riordan, S., Saha, A., Sauer, P. U., Sawatzky, B., Schiavilla, R., Shabestari, M., Shahinyan, A., Schoenrock, B., Širca, S., Skibiński, R., John, J. St., Subedi, R., Sulkosky, V., Tobias, W. A., Tireman, W., Urciuoli, G. M., Viviani, M., Wang, D., Wang, K., Wang, Y., Watson, J., Wojtsekhowski, B., Witała, H., Ye, Z., Zhan, X., Zhang, Y., Zheng, X., Zhao, B., and Zhu, L.

Subjects
Nuclear Experiment
Abstract

We present a precise measurement of double-polarization asymmetries in the $^3\vec{\mathrm{He}}(\vec{\mathrm{e}},\mathrm{e}'\mathrm{d})$ reaction. This particular process is a uniquely sensitive probe of hadron dynamics in $^3\mathrm{He}$ and the structure of the underlying electromagnetic currents. The measurements have been performed in and around quasi-elastic kinematics at $Q^2 = 0.25\,(\mathrm{GeV}/c)^2$ for missing momenta up to $270\,\mathrm{MeV}/c$. The asymmetries are in fair agreement with the state-of-the-art calculations in terms of their functional dependencies on $p_\mathrm{m}$ and $\omega$, but are systematically offset. Beyond the region of the quasi-elastic peak, the discrepancies become even more pronounced. Thus, our measurements have been able to reveal deficiencies in the most sophisticated calculations of the three-body nuclear system, and indicate that further refinement in the treatment of their two- and/or three-body dynamics is required., Comment: 6 pages, 4 figures, accepted for publication at Phys. Rev. Lett

Published
2014
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7. Cross Section Measurements of Charged Pion Photoproduction in Hydrogen and Deuterium from 1.1 to 5.5 GeV

Author

Jefferson Lab Hall A Collaboration, Collaboration, Jefferson Lab E94-104, and Zhu, L. Y.

Subjects
Nuclear Experiment
Abstract

The differential cross section for the gamma +n --> pi- + p and the gamma + p --> pi+ n processes were measured at Jefferson Lab. The photon energies ranged from 1.1 to 5.5 GeV, corresponding to center-of-mass energies from 1.7 to 3.4 GeV. The pion center-of-mass angles varied from 50 degree to 110 degree. The pi- and pi+ photoproduction data both exhibit a global scaling behavior at high energies and high transverse momenta, consistent with the constituent counting rule prediction and the existing pi+ data. The data suggest possible substructure of the scaling behavior, which might be oscillations around the scaling value. The data show an enhancement in the scaled cross section at center-of-mass energy near 2.2 GeV. The differential cross section ratios at high energies and high transverse momenta can be described by calculations based on one-hard-gluon-exchange diagrams., Comment: 18 pages, 19 figures

Published
2004
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8. Measurement of the Generalized Polarizabilities of the Proton in Virtual Compton Scattering at Q2= 0.92 and 1.76 GeV2

Author

The Jefferson Lab Hall A Collaboration and Laveissiere, G.

Subjects
High Energy Physics - Phenomenology
Abstract

We report a Virtual Compton Scattering study of the proton at low CM energies. We have determined the structure functions $P_{LL}-P_{TT}/\epsilon$ and $P_{LT}$, and the electric and magnetic Generalized Polarizabilities (GPs) $\alpha_E(Q2)$ and $\beta_M(Q2)$ at momentum transfer Q2= 0.92 and 1.76 GeV2. The electric GP shows a strong fall-off with Q2, and its global behavior does not follow a simple dipole form. The magnetic GP shows a rise and then a fall-off; this can be interpreted as the dominance of a long-distance diamagnetic pion cloud at low Q2, compensated at higher Q2 by a paramagnetic contribution from $\pi N$ intermediate states., Comment: 4 pages, 2 Figs. Version for PRL after PRL cancelled their request for reducing length of paper

Published
2004
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9. Measurement of the Generalized Polarizabilities of the Proton in Virtual Compton Scattering at Q2=0.92 and 1.76 Gev2: II. Dispersion Relation Analysis

Author

The Jefferson Lab Hall A Collaboration and Laveissiere, G.

Subjects
High Energy Physics - Phenomenology
Abstract

Virtual Compton Scattering is studied at the Thomas Jefferson National Accelerator Facility in the energy domain below pion threshold and in the Delta(1232) resonance region. The data analysis is based on the Dispersion Relation (DR) approach. The electric and magnetic Generalized Polarizabilities (GPs) of the proton and the structure functions Pll-Ptt/epsilon and Plt are determined at four-momentum transfer squared Q2=0.92 and 1.76 GeV2. The DR analysis is consistent with the low-energy expansion analysis. The world data set indicates that neither the electric nor magnetic GP follows a simple dipole form., Comment: 4 pages, 3 figures, to be submitted to PRL

Published
2003

10. Measurement of the Generalized Polarizabilities of the Proton in Virtual Scattering at Q2=0.92 and 1.76 GeV2: I. Low Energy Expansion Analysis

Author

The Jefferson Lab Hall A Collaboration and Jaminion, S.

Subjects
High Energy Physics - Phenomenology
Abstract

Virtual Compton Scattering is studied at the Thomas Jefferson National Accelerator Facility at low Center-of-Mass energies, below pion threshold. Following the Low Energy Theorem for the $ ep \to ep \gamma$ process, we obtain values for the two structure functions Pll-Ptt/epsilon and Plt at four-momentum transfer squared Q2=0.92 and 1.76 GeV2., Comment: 4 pages, 2 figures, to be submitted to PRL. Figs 1 and 2, lettering enlarged

Published
2003
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11. The reaction dynamics of the 16O(e,e'p) cross section at high missing energies

Author

Jefferson Lab Hall A Collaboration and Liyanage, N.

Subjects
Nuclear Experiment
Abstract

We measured the cross section and response functions (R_L, R_T, and R_LT) for the 16O(e,e'p) reaction in quasielastic kinematics for missing energies 25 <= E_miss <= 120 MeV at various missing momenta P_miss <= 340 MeV/c. For 25 < E_miss < 50 MeV and P_miss \approx 60 MeV/c, the reaction is dominated by single-nucleon knockout from the 1s1/2-state. At larger P_miss, the single-particle aspects are increasingly masked by more complicated processes. For E_miss > 60 MeV and P_miss > 200 MeV/c, the cross section is relatively constant. Calculations which include contributions from pion exchange currents, isobar currents and short-range correlations account for the shape and the transversity but only for half of the magnitude of the measured cross section., Comment: 6 pages, 4 figures, submitted to Phys Rev Lett, formatting error fixed

Published
2000
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12. Gep/Gmp for bound protons: first results for 16O with the recoil polarization technique

Author

Jefferson Lab Hall A Collaboration and Malov, S.

Subjects
Nuclear Experiment
Abstract

The first (e,e'p) polarization transfer measurements on a nucleus heavier than deuterium have been carried out at Jefferson Laboratory. Transverse and longitudinal components of the polarization of protons ejected in the reaction 16O(e,e'p) were measured in quasielastic perpendicular kinematics at a Q^2 of 0.8 (GeV/c)^2. The data are in good agreement with state of the art calculations, but do not exclude possible changes in the ratio of the electric to magnetic form factors of the nucleon in the nuclear medium at the level of recent theoretical predictions., Comment: 5 pages, 2 figures, uses revtex.sty

Published
2000

13. The ratio of proton's electric to magnetic form factors measured by polarization transfer

Author

The Jefferson Lab Hall A Collaboration and Jones, M. K.

Subjects
Nuclear Experiment
Abstract

The ratio of the proton's elastic electromagnetic form factors was obtained by measuring the transverse and longitudinal polarizations of recoiling protons from the elastic scattering of polarized electrons with unpolarized protons. The ratio of the electric to magnetic form factor is proportional to the ratio of the transverse to longitudinal recoil polarizations. The ratio was measured over a range of four-momentum transfer squared between 0.5 and 3.5 GeV-squared. Simultaneous measurement of transverse and longitudinal polarizations in a polarimeter provides good control of the systematic uncertainty. The results for the ratio of the proton's electric to magnetic form factors show a systematic decrease with increasing four momentum squared, indicating for the first time a marked difference in the spatial distribution of charge and magnetization currents in the proton., Comment: 5 pages, 2 figures, version of paper after corrections due to referees comments and shortened by removing one figure for Physical Review Letters

Published
1999
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14. Large Momentum Transfer Measurements of the Deuteron Elastic Structure Function A(Q^2) at Jefferson Laboratory

Author

The Jefferson Lab Hall A Collaboration and Alexa, L. C

Subjects
Nuclear Experiment, High Energy Physics - Experiment
Abstract

The deuteron elastic structure function A(Q^2) has been extracted in the Q^2 range 0.7 to 6.0 (GeV/c)^2 from cross section measurements of elastic electron-deuteron scattering in coincidence using the Hall A Facility of Jefferson Laboratory. The data are compared to theoretical models based on the impulse approximation with inclusion of meson-exchange currents, and to predictions of quark dimensional scaling and perturbative quantum chromodynamics, Comment: Submitted to Physical Review Letters

Published
1998
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15. Hypernuclear spectroscopy in JLab’s Hall A

Author

The Hall A Collaboration, LeRose, J. J., Acha, A., Bydžovský, P., Chang, C. C., Cisbani, E., Cusanno, F., de Jager, C. W., De Leo, R., Feuerbach, R. J., Frullani, S., Garibaldi, F., Higinbotham, D. W., Iodice, M., Lagamba, L., Markowitz, P., Marrone, S., Reitz, B., Sotona, M., Urciuoli, G. M., Pochodzalla, Josef, editor, and Walcher, Thomas, editor

Published
2007
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16. Polarization Observables in the N→Δ(1232) Transition

Author

The Jefferson Lab Hall a Collaboration, Frullani, Salvatore, Kelly, James J., Sarty, Adam J., Lourie, Robert W., Jones, Mark K., Meekins, Dave G., Bertozzi, William, Chai, Zhengwei, Gilad, Shalev, Roché, Rikki E., Steffens, Erhard, editor, and Shanidze, Revaz, editor

Published
2003
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18. Deeply virtual Compton scattering cross section at high Bjorken x_{B}

Author

Georges, F, Rashad, M. N. H., Stefanko, A, Dlamini, M, Karki, B, Ali, S. F., 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, John, 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, M. E., Cisbani, E, Clary, B, Cohen, E, Compton, N, Cornejo, J. C., 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, V. M., Gu, C, Hague, T, Hamad, G, Hamilton, David, Hamilton, K., Hansen, O, Hauenstein, F, Henry, W, Higinbotham, D. W., Holmstrom, T, Horn, T, Huang, Y, Huber, G. M., Hyde, C. E., Ibrahim, H, Jen, C-M, Jin, K, Jones, M, Kabir, A, Keppel, C, Khachatryan, V, King, P. M., Li, S, Li, W. B., Liu, J, Liu, H, Liyanage, A, Magee, J, Malace, S, Mammei, J, Markowitz, P, McClellan, E, Mazouz, M, Meddi, F, Meekins, D, Mesik, K, Michaels, R, Mkrtchyan, A, Montgomery, Rachel, Muñoz Camacho, C, Myers, L. S., Nadel-Turonski, P, Nazeer, S. J., Nelyubin, V, Nguyen, D, Nuruzzaman, N, Nycz, M, Obretch, O. F., Ou, L, Palatchi, C, Pandey, B, Park, S, Park, K, Peng, C, Pomatsalyuk, R, Pooser, E, Puckett, A. J. R., Punjabi, V, Quinn, B, Rahman, S, Reimer, P. E., Roche, J, Sapkota, I, Sarty, A, Sawatzky, B, Saylor, N. H., Schmookler, B, Shabestari, M. H., Shahinyan, A, Sirca, S, Smith, G. R., Sooriyaarachchilage, S, Sparveris, N, Spies, R, Su, T, Subedi, A, Sulkosky, V, Sun, A, Thorne, L, Tian, Y, Ton, N, Tortorici, F, Trotta, R, Urciuoli, G. M., Voutier, E, Waidyawansa, B, Wang, Y, Wojtsekhowski, B, Wood, S, Yan, X, Ye, L, Ye, Z, Yero, C, Zhang, J, Zhao, Y, Zhu, P, and Jefferson Lab Hall A Collaboration

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

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

Author

The Jefferson Lab Hall A Collaboration, Dlamini, M., Karki, B., Ali, S. F., Lin, P-J., Georges, F., Ko, H-S, Israel, N., Rashad, M. N. H., 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., Gayoso, C. Ayerbe, 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, M. E., Cisbani, E., Clary, B., Cohen, E., Compton, N., Cornejo, J. C., Dusa, S. Covrig, 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, V. M., Gu, C., Hague, T., Hamad, G., Hamilton, D., Hamilton, K., Hansen, O., Hauenstein, F., Henry, W., Higinbotham, D. W., Holmstrom, T., Horn, T., Huang, Y., Huber, G. M., Hyde, C., Ibrahim, H., Jen, C-M., Jin, K., Jones, M., Kabir, A., Keppel, C., Khachatryan, V., King, P. M., Li, S., Li, W., Liu, J., Liu, H., Liyanage, A., Magee, J., Malace, S., Mammei, J., Markowitz, P., McClellan, E., Meddi, F., Meekins, D., Mesik, K., Michaels, R., Mkrtchyan, A., Montgomery, R., Camacho, C. Munoz, Myers, L. S., Nadel-Turonski, P., Nazeer, S. J., Nelyubin, V., Nguyen, D., Nuruzzaman, N., Nycz, M., Obretch, O. F., Ou, L., Palatchi, C., Pandey, B., Park, S., Park, K., Peng, C., Pomatsalyuk, R., Pooser, E., Puckett, A. J. R., Punjabi, V., Quinn, B., Rahman, S., Reimer, P. E., Roche, J., Sapkota, I., Sarty, A., Sawatzky, B., Saylor, N. H., Schmookler, B., Shabestari, M. H., Shahinyan, A., Sirca, S., Smith, G. R., Sooriyaarachchilage, S., Sparveris, N., Spies, R., Su, T., Subedi, A., Sulkosky, V., Sun, A., Thorne, L., Tian, Y., Ton, N., Tortorici, F., Trotta, R., Urciuoli, G. M., Voutier, E., Waidyawansa, B., Wang, Y., Wojtsekhowski, B., Wood, S., Yan, X., Ye, L., Ye, Z., Yero, C., Zhang, J., Zhao, Y., Zhu, P., Laboratoire de Physique des 2 Infinis Irène Joliot-Curie (IJCLab), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), and Jefferson Lab Hall A

Subjects
[PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], momentum transfer dependence, helicity, High Energy Physics - Experiment, pi: distribution amplitude, generalized parton distribution: transversity, kinematics, pi0: electroproduction, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], quark: valence, polarization: transverse, High Energy Physics::Experiment, p: structure function, Nuclear Experiment, experimental results, photon: virtual, Jefferson Lab
Abstract

International audience; We report measurements of the exclusive neutral pion electroproduction cross section off protons at large values of xB (0.36, 0.48, and 0.60) and Q2 (3.1 to 8.4 GeV2) obtained from Jefferson Lab Hall A experiment E12-06-014. The corresponding structure functions dσT/dt+εdσL/dt, dσTT/dt, dσLT/dt, and dσLT′/dt are extracted as a function of the proton momentum transfer t-tmin. 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

25. Measurement of double-polarization asymmetries in the quasi-elastic 3He (e, e'p) process

Author

Mihovilovič, M., Jin, G., Long, E., Zhang, Yi, Allada, K., Sauer, P.U., and The Jefferson Lab Hall A Collaboration

Subjects
Quantum electrodynamics, Kinematics, Breakup, Spin structure, Physics, Observable, Nuclear Theory, Particle physics, Polarization (waves), p-process, Reaction dynamics, ddc:530, Elasticity (economics), Dewey Decimal Classification::500 | Naturwissenschaften::530 | Physik, Nuclear Experiment
Abstract

We report on a precise measurement of double-polarization asymmetries in electron-induced breakup of He 3 proceeding to pd and ppn final states, performed in quasi-elastic kinematics at Q 2 = 0.25 ( GeV / c ) 2 for missing momenta up to 250 MeV / c . These observables represent highly sensitive tools to investigate the electromagnetic and spin structure of He 3 and the relative importance of two- and three-body effects involved in the breakup reaction dynamics. The measured asymmetries cannot be satisfactorily reproduced by state-of-the-art calculations of He 3 unless their three-body segment is adjusted, indicating that the spin-dependent part of the nuclear interaction governing the three-body breakup process is much smaller than previously thought.

Published
2019
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26. High-resolution hypernuclear spectroscopy at Jefferson Lab, Hall A

Author

Jefferson Lab Hall A Collaboration, Garibaldi, F., Acha, A., Ambrozewicz, P., Aniol, K. A., Beturin, P., Benaoum, H., Benesch, J., Bertin, P. Y., Blomqvist, K. I., Boeglin, W. U., Breuer, H., Brindza, P., Bydzovsky, P., Camsonne, A., Chang, C. C., Chen, J. -P., Choi, Seonho, Chudakov, E. A., Cisbani, E., Colilli, S., Coman, L., Cusanno, F., Craver, B. J., De Cataldo, G., de Jager, C. W., De Leo, R., Deur, A. P., Ferdi, C., Feuerbach, R. J., Folts, E., Frullani, S., Gayou, O., Giuliani, F., Gomez, J., Gricia, M., Hansen, J. O., Hayes, D., Higinbotham, D. W., Holmstrom, T. K., Hyde, C. E., Ibrahim, H. F., Iodice, M., Jiang, X., Kaufman, L. J., Kino, K., Kross, B., Lagamba, L., LeRose, J. J., Lindgren, R. A., Lucentini, M., Margaziotis, D. J., Markowitz, P., Marrone, S., Meekins, D. G., Meziani, Z. E., McCormick, K., Michaels, R. W., Millener, D. J., Miyoshi, T., Moffit, B., Monaghan, P. A., Moteabbed, M., Camacho, C. Munoz, Nanda, S., Nappi, E., Nelyubin, V. V., Norum, B. E., Okasyasu, Y., Paschke, K. D., Perdrisat, C. F., Piasetzky, E., Punjabi, V. A., Qiang, Y., Raue, B., Reimer, P. E., Reinhold, J., Reitz, B., Roche, R. E., Rodriguez, V. M., Saha, A., Santavenere, F., Sarty, A. J., Segal, J., Shahinyan, A., Singh, J., Sirca, S., Snyder, R., Solvignon, P. H., Sotona, M., Subedi, R., Sulkosky, V. A., Suzuki, T., Ueno, H., Ulmer, P. E., Urciuoli, G. M., Voutier, E., Wojtsekhowski, B. B., Zheng, X., Zorn, C., Laboratoire de Physique de Clermont (LPC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Département de Physique Nucléaire (ex SPhN) (DPHN), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Jefferson Lab Hall A, Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Clermont Auvergne (UCA)-Centre National de la Recherche Scientifique (CNRS), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)

Subjects
Nuclear Theory, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], 010308 nuclear & particles physics, FOS: Physical sciences, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Structure, 01 natural sciences, Nuclear Theory (nucl-th), 0103 physical sciences, Nuclear Experiment (nucl-ex), 010306 general physics, Nuclear Experiment
Abstract

The experiment E94-107 in Hall A at Jefferson Lab started a systematic study of high resolution hypernuclear spectroscopy in the 0p-shell region of nuclei such as the hypernuclei produced in electroproduction on 9Be, 12C and 16O targets. In order to increase counting rates and provide unambiguous kaon identification two superconducting septum magnets and a ring-imaging Cherenkov detector were added to the Hall A standard equipment. The high-quality beam, the good spectrometers and the new experimental devices allowed us to obtain very good results. For the first time, measurable strength with sub-MeV energy resolution was observed for the core-excited states of Lambda 12B. A high-quality Lambda 16N hypernuclear spectrum was likewise obtained. A first measurement of the Lambda binding energy for Lambda 16N, calibrated against the elementary reaction on hydrogen, was obtained with high precision, 13.76 +/- 0.16 MeV. Similarly, the first Lambda 9Li hypernuclear spectrum shows general agreement with theory (distorted-wave impulse approximation with the SLA and BS3 electroproduction models and shell-model wave functions). Some disagreement exists with respect to the relative strength of the states making up the first multiplet. A Lambda separation energy of 8.36 MeV was obtained, in agreement with previous results. It has been shown that the electroproduction of hypernuclei can provide information complementary to that obtained with hadronic probes and the gamma-ray spectroscopy technique., Comment: 27 pages, 18 figures, submitted to Physical Review C

Published
2019

27. Hard Two-Body Photodisintegration of 3He

Author

I. Pomerantz, Y. Ilieva, R. Gilman, D. W. Higinbotham, E. Piasetzky, S. Strauch, D. Ho, H. Y. Lu, Meyer, Curtis, Schumacher, Reinhard A., Vernarsky, Brian, CLAS Collaboration, and Hall-A Collaboration

Subjects
Nuclear Theory, FOS: Physical sciences, 20399 Classical Physics not elsewhere classified, Nuclear Experiment
Abstract

We have measured cross sections for the γHe3→pd reaction at photon energies of 0.4–1.4 GeV and a center-of-mass angle of 90°. We observe dimensional scaling above 0.7 GeV at this center-of-mass angle. This is the first observation of dimensional scaling in the photodisintegration of a nucleus heavier than the deuteron.

Published
2013
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28. Recoil polarization for Delta excitation in pion electroproduction - art. no. 102002

Author

Kelly, JJ Roche, RE Chai, Z Jones, MK Gayou, O and Sarty, AJ Frullani, S Aniol, K Beise, EJ Benmokhtar, F and Bertozzi, W Boeglin, WU Botto, T Brash, EJ Breuer, H and Brown, E Burtin, E Calarco, JR Cavata, C Chang, CC and Chant, NS Chen, JP Coman, M Crovelli, D De Leo, R and Dieterich, S Escoffier, S Fissum, KG Garde, V and Garibaldi, F Georgakopoulus, S Gilad, S Gilman, R and Glashausser, C Hansen, JO Higinbotham, DW Hotta, A and Huber, GM Ibrahim, H Iodice, M de Jager, CW Jiang, X and Klimenko, A Kozlov, A Kumbartzki, G Kuss, M Lagamba, L and Laveissiere, G LeRose, JJ Lindgren, RA Liyanage, N and Lolos, GJ Lourie, RW Margaziotis, DJ Marie, F Markowitz, P McAleer, S Meekins, D Michaels, R Milbrath, BD and Mitchell, J Nappa, J Neyret, D Perdrisat, CF Potokar, M and Punjabi, VA Pussieux, T Ransome, RD Roos, PG and Rvachev, M Saha, A Sirca, S Suleiman, R Strauch, S and Templon, JA Todor, L Ulmer, PE Urciuoli, GM Weinstein, LB Wijesooriya, K Wojtsekhowski, B Zheng, X Zhu, L and Jefferson Lab E91011 Collaboration Hall A Collaboration

Abstract

We measured angular distributions of recoil-polarization response functions for neutral pion electroproduction for W=1.23 GeV at Q(2)=1.0 (GeV/c)(2), obtaining 14 separated response functions plus 2 Rosenbluth combinations; of these, 12 have been observed for the first time. Dynamical models do not describe quantities governed by imaginary parts of interference products well, indicating the need for adjusting magnitudes and phases for nonresonant amplitudes. We performed a nearly model-independent multipole analysis and obtained values for Re (S1+/M1+)= -(6.84 +/- 0.15)% and Re (E1+/M1+)= -(2.91 +/- 0.19)% that are distinctly different from those from the traditional Legendre analysis based upon M1+ dominance and l(pi)

Published
2005

29. Recoil polarization for neutral pion electroproduction near the delta resonance

Author

Kelly (for the Jefferson Laboratory Hall A Collaboration), James J.

Subjects
pion electroproduction, recoil polarization, delta resonance, multipole analysis
Abstract

We have measured angular distributions for recoil polarization in the p(~e, e ′ ~p)π 0 reaction at Q2 ≈ 1 (GeV/c) 2 with 1.16 ≤ W ≤ 1.36 GeV across the ∆ resonance. The data are compared with representative models and a truncated Legendre analysis is compared with a more general multipole analysis., Mjerili smo kutne raspodjele polarizacije u odboju u reakciji p(~e, e ′ ~p)π 0 za Q2 ≈ 1 (GeV/c) 2 i 1.16 ≤ W ≤ 1.36 GeV u području ∆ rezonancije. Podaci se uspoređuju s odabranim modelima, a krnja Legendreova analiza uspoređuje se s općenitijom multipolnom analizom.

Published
2004

30. Measurement of the deuteron elastic structure functions A(q2) and B(q2) at large momentum transfers

Author

McCormick (for the Jefferson Lab Hall A Collaboration), Kathy

Subjects
deuteron, “electric” and “magnetic” structure functions, scaling
Abstract

The cross section for elastic electron-deuteron scattering was measured in Jefferson Lab experiment 91-026. The deuteron elastic structure functions A(Q2 ) and B(Q2 ) have been extracted from the data. The final results for the “electric” structure function, A(Q2 ), in the range of 0.7 ≤ Q2 ≤ 6.0 (GeV/c)2 , are presented. Preliminary results for the “magnetic” structure function, B(Q2 ), are presented in the range of 0.7 ≤ Q2 ≤ 1.35 (GeV/c)2 . These data are compared to the theoretical predictions of both meson-nucleon and quark-gluon based models., Mjerili smo udarne presjeke za elastično raspršenje elektrona na deuteronu i odredili elastične strukturne funkcije deuterona A(Q2) and B(Q2).

Published
1999

31. Measurement of recoil polarization in the 16^O (→ e , e′ → p) reaction

Author

Jones (for the Jefferson Lab Hall A Collaboration), M. K.

Subjects
electric and magnetic form factors of proton, modification in nuclear medium, 16O(→ e , e′ → p) reaction, quasifree kinematics, longitudinal and transverse polarization of outgoing proton
Abstract

The longitudinal and transverse components of the polarization of the outgoing proton were measured for the reaction 16^O (→ e , e′ → p) at a four-momentum transfer squared of 0.8 GeV2 in quasifree kinematics. These were the first measurements of polarization transfer observables for a complex nucleus. Comparison of the ratio of the transverse and longitudinal polarization to theoretical predictions allows the study of modification of the proton’s form factors in the nuclear medium., Mjerile su se uzdužna i poprečna komponenta polarizacije izlaznih protona u reakciji 16^O (→ e , e′ → p) za kvadrat prijenosa impulsa od 0.8 GeV2 , u kvazislobodnim kinematičkim uvjetima. Ovo su prva mjerenja prijenosa polarizacije za složenu jezgru. Usporedba omjera poprečne i uzdužne polarizacije s teorijskim predviđanjima omogućava proučavanje promjena faktora oblika protona kada je u nuklearnom okruženju.

Published
1999

32. Measurement of the ratio of the proton's electric to magnetic form factors by recoil polarization

Author

Jones (for the Jefferson Lab Hall A Collaboration), M. K.

Subjects
proton, ratio of electric to magnetic form factors
Abstract

The longitudinal and transverse polarizations of the outgoing proton were measured for the reaction 1H(→ e , e′ → p) at four-momentum transfer squared of 0.5 to 3.5 GeV2 . The ratio of the electric to magnetic form factors of the proton is proportional to the ratio of the transverse to longitudinal polarizations., Mjerila se uzdužna i poprečna polarizacija izlaznih protona u reakciji 1H(→ e , e′ → p) za kvadrate prijenosa četiri-impulsa od 0.5 do 3.5 GeV2 . Omjer električnog i magnetskog faktora oblika protona je razmjeran omjeru poprečne i uzdužne polarizacije.

Published
1999

33. Cross section measurements of charged pion photoproduction in hydrogen and deuterium from 1.1 to 5.5 GeV

Author

Zhu, L.Y., Zhu, L.Y., Arrington, J., Averett, T., Beise, E., Calarco, J., Chang, T., Chen, J.P., Chudakov, E., Coman, M., Clasie, B., Crawford, C., Dieterich, S., Dohrmann, F., Dutta, D., Fissum, K., Frullani, S., Gao, H., Gilman, R., Glashausser, C., Gomez, J., Hafidi, K., Hansen, O., Higinbotham, D.W., Holt, R.J., de Jager, C.W., Jiang, X., Kinney, E., Kramer, K., Kumbartzki, G., LeRose, J., Liyanage, N., Mack, D., Markowitz, P., McCormick, K., Meekins, D., Meziani, Z.-E., Michaels, R., Mitchell, J., Nanda, S., Potterveld, D., Ransome, R., Reimer, P.E., Reitz, B., Saha, A., Schulte, E.C., Seely, J., Sirca, S., Strauch, S., Sulkosky, V., Vlahovic, B., Weinstein, L.B., Wijesooriya, K., Williamson, C., Wojtsekhowski, B., Xiang, H., Xiong, F., Xu, W., Zeng, J., Zheng, X., Jefferson Lab Hall A Collaboration, Jefferson Lab E94-104 Collaboration, Zhu, L.Y., Zhu, L.Y., Arrington, J., Averett, T., Beise, E., Calarco, J., Chang, T., Chen, J.P., Chudakov, E., Coman, M., Clasie, B., Crawford, C., Dieterich, S., Dohrmann, F., Dutta, D., Fissum, K., Frullani, S., Gao, H., Gilman, R., Glashausser, C., Gomez, J., Hafidi, K., Hansen, O., Higinbotham, D.W., Holt, R.J., de Jager, C.W., Jiang, X., Kinney, E., Kramer, K., Kumbartzki, G., LeRose, J., Liyanage, N., Mack, D., Markowitz, P., McCormick, K., Meekins, D., Meziani, Z.-E., Michaels, R., Mitchell, J., Nanda, S., Potterveld, D., Ransome, R., Reimer, P.E., Reitz, B., Saha, A., Schulte, E.C., Seely, J., Sirca, S., Strauch, S., Sulkosky, V., Vlahovic, B., Weinstein, L.B., Wijesooriya, K., Williamson, C., Wojtsekhowski, B., Xiang, H., Xiong, F., Xu, W., Zeng, J., Zheng, X., Jefferson Lab Hall A Collaboration, and Jefferson Lab E94-104 Collaboration

Abstract

The differential cross sections for the γn→π-p and the γp→π+n processes were measured at Jefferson Lab. The photon energies ranged from 1.1 to 5.5 GeV, corresponding to center-of-mass energies from 1.7 to 3.4 GeV. The pion center-of-mass angles varied from 50° to 110°. The π- and π+ photoproduction data both exhibit a global scaling behavior at high energies and high transverse momenta, consistent with the constituent counting rule prediction and the existing π+ data. The data suggest possible substructure of the scaling behavior, which might be oscillations around the scaling value. The data show an enhancement in the scaled cross section at center-of-mass energy near 2.2 GeV. The differential cross section ratios [dσ/dt(γn→π-p)/dσ/dt(γp→π+n)] at high energies and high transverse momenta can be described by calculations based on one-hard-gluon-exchange diagrams.

Published
2005

34. LowQ2measurements of the neutron and3He spin structure

Author

V A Sulkosky and the Jefferson Lab Hall A Collaboration

Subjects
Physics, History, Particle physics, Chiral perturbation theory, Photon, Nuclear Theory, Momentum transfer, Particle accelerator, Computer Science Applications, Education, law.invention, Nuclear physics, law, Neutron, Sum rule in quantum mechanics, Perturbation theory (quantum mechanics), Nuclear Experiment, Spin-½
Abstract

Thomas Jefferson National Accelerator Facility experiment E97-110 was performed to provide a precise measurement of the extended Gerasimov-Drell-Hearn integral and of moments of the neutron and of the 3He spin structure functions. The momentum transfer range 0.02 < Q2 < 0.3 (GeV/c)2 will allow us to test predictions of Chiral Perturbation Theory, and chek the GDH sum rule by extrapolating the integral to the real photon point. The data have been taken in Hall A using a highly polarized electron beam and a polarized 3He target. The status of the data analysis is discussed, and preliminary results are shown.

Published
2007

35. Preliminary results of a precision measurement of the neutron d2: Probing the Lorentz color force.

Author

Flay, D., Jefferson Lab Hall A Collaboration, and E06-014 Collaboration

Subjects
*QUANTUM chromodynamics, *LORENTZ force, *QUARKS, *POLARIZATION (Nuclear physics), *DEEP inelastic collisions, *CHIRALITY of nuclear particles, *SOLITONS, *STANDARD deviations
Abstract

The quantity d2, related to a twist-three matrix element, is a measure of the average restoring Lorentz color force experienced by a quark inside a polarized nucleon after it is struck by a virtual photon in electron Deep Inelastic Scattering (DIS). With its information encoded in both spin structure functions g1 and g2 in the quark valence region at large Bjorken x, this confining local force is a result of the remnant di-quark system attracting the struck quark. While bag-and chiralsoliton-model calculations for the neutron d2 are consistent with those of lattice Quantum Chromodynamics (QCD), current experimental data differ by approximately two standard deviations from those theoretical results. To address this issue, the experiment E06-014 was carried out from February to March of 2009 at Jefferson Lab. It consisted of measuring doublespin asymmetries and the total cross section by scattering a longitudinally polarized electron beam from a longitudinally or transversely polarized 3He target, allowing for the extraction of the neutron d2. The experiment covered excitation energies in the resonance and DIS valence quark regions. Preliminary cross sections and asymmetries will be presented. [ABSTRACT FROM AUTHOR]

Published
2012
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36. Precision measurement of longitudinal and transverse response functions of quasi-elastic electron scattering in the momentum transfer range 0.55 GeV/c≤|q vector |≤0.9GeV/c.

Author

Yao, Huan, Jefferson Lab Hall A Collaboration, and E05-110 Collaboration

Subjects
*PHYSICAL measurements, *LONGITUDINAL method, *ELECTRON scattering, *MOMENTUM transfer, *VECTOR mesons, *COULOMB'S law, *SUM rules (Physics), *NUCLEAR cross sections
Abstract

In order to test the Coulomb sum rule in nuclei, a precision measurement of inclusive electron scattering cross sections in the quasi-elastic region was performed at Jefferson Lab. Incident electrons of energies ranging from 0.4 GeV/c to 4 GeV/c scattered off 4He, 12C, 56Fe and 208Pb nuclei at four scattering angles (15°, 60°, 90°, 120°) and scattered energies ranging from 0.1 GeV/c to 4 GeV/c. The Rosenbluth method with proper Coulomb corrections is used to extract the transverse and longitudinal response functions at three-momentum transfers 0.55GeV/c≤|q→|≤1.0GeV/c. The Coulomb Sum is determined in the same |q→| range as mentioned above and will be compared to predictions. Analysis progress and preliminary results will be presented. [ABSTRACT FROM AUTHOR]

Published
2012
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40. Precision Measurement of the p(e,e′p)π0 Reaction at Threshold

Author

Chirapatpimol, K., Shabestari, M.H., Lindgren, R.A., Smith, L.C., Annand, J.R.M., Higinbotham, D.W., Moffit, B., Nelyubin, V., Norum, B.E., Allada, K., Aniol, K., Ardashev, K., Armstrong, D.S., Arndt, R.A., Benmokhtar, F., Bernstein, A.M., Bertozzi, W., Briscoe, W.J., Bimbot, L., Camsonne, A., Chen, J.-P., Choi, S., Chudakov, E., Cisbani, E., Cusanno, F., Dalton, M.M., Dutta, C., Egiyan, K., Fernàndez-Ramìrez, C., Feuerbach, R., Fissum, K.G., Frullani, S., Garibaldi, F., Gayou, O., Gilman, R., Gilad, S., Goity, J., Gomez, J., Hahn, B., Hamilton, D., Hansen, J.-O., Huang, J., Igarashi, R., Ireland, D., De Jager, C.W., Jin, X., Jiang, X., Jinasundera, T., Kellie, J., Keppel, C.E., Kolb, N., LeRose, J., Liyanage, N., Livingston, K., McNulty, D., Mercado, L., Michaels, R., Mihovilovič, M., Qian, S., Qian, X., Mailyan, S., Mamyan, V., Marrone, S., Monaghan, P., Nanda, S., Perdrisat, C.F., Piasetzky, E., Protopopescu, D., Punjabi, V., Qiang, Y., Rachek, I.A., Rakhman, A., Riordan, S., Ron, G., Rosner, G., Saha, A., Sawatzky, B., Shahinyan, A., Širca, S., Sparveris, N., Subedi, R.R., Suleiman, R., Strakovsky, I., Sulkosky, V., Moinelo, J., Voskanyan, H., Wang, K., Wang, Y., Watson, J., Watts, D., Wojtsekhowski, B., Workman, R.L., Yao, H., Zhan, X., Zhang, Y., Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Hall A Collaboration

Subjects
[PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment
Abstract

International audience; New results are reported from a measurement of π0 electroproduction near threshold using the p(e,e′p)π0 reaction. The experiment was designed to determine precisely the energy dependence of s- and p-wave electromagnetic multipoles as a stringent test of the predictions of chiral perturbation theory (ChPT). The data were taken with an electron beam energy of 1192 MeV using a two-spectrometer setup in Hall A at Jefferson Lab. For the first time, complete coverage of the ϕ∗π and θ∗π angles in the pπ0 center of mass was obtained for invariant energies above threshold from 0.5 up to 15 MeV. The 4-momentum transfer Q2 coverage ranges from 0.05 to 0.155 (GeV/c)2 in fine steps. A simple phenomenological analysis of our data shows strong disagreement with p-wave predictions from ChPT for Q2>0.07 (GeV/c)2, while the s-wave predictions are in reasonable agreement.

Published
2015

41. Exploration de la diffusion Compton profondément virtuelle sur le neutron dans le hall A du Jefferson Laboratory

Author

Malek Mazouz, Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS), Université Joseph-Fourier - Grenoble I, Eric Voutier(voutier@lpsc.in2p3.fr), JLab/Hall A collaboration, and Mazouz, Malek

Subjects
[PHYS.NUCL] Physics [physics]/Nuclear Theory [nucl-th], Quark, Particle physics, Hadronic physics, Jefferson Lab (CEBAF), [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], Hadron, Deeply Virtual Compton Scattering (DVCS), Parton, DiffusionCompton Profondément Virtuelle (DVCS), Structure du nucléon, Réactionsexclusives, Nuclear physics, Electromagnetic probe, Nucleon structure, Neutron, Quark angular momentum, Nuclear Experiment, Physics, Luminosity (scattering theory), Physique hadronique, High Energy Physics::Phenomenology, Compton scattering, Gluon, Distributions de Partons Généralisées (GPDs), Exclusive reactions, Generalized Parton Distributions (GPDs), Quark–gluon plasma, High Energy Physics::Experiment, Sonde électromagnétique, Moment angulaire des quarks
Abstract

Generalized Parton Distributions (GPDs) are universal functions which provide a comprehensive description of hadron properties in terms of quarks and gluons. Deeply Virtual Compton Scattering (DVCS) is the simplest hard exclusive processinvolving GPDs. In particular, the DVCS on the neutron is mostly sensitive to E, the less constrained GPD, wich allows to access to the quark angular momentum. The first dedicated DVCS experiment on the neutron ran in the Hall A of Jefferson Lab in fall 2004. The high luminosity of the experiment and the resulting background rate recquired specific devices which are decribed in this document. The analysis methods and the experiment results, leading to preliminary constraints on the GPD E, are presented., Les distributions généralisées de partons (GPDs) sont des fonctions universelles permettant une meilleure compréhension des propriétés des nucléons en termes de quarks et de gluons. La diffusion Compton profondément virtuelle (DVCS) est le processus le pus simple permettant leur mesure. En particulier, le DVCS sur le neutron est sensible à la GPD E qui est la moins contrainte à ce jour et dont la connaissance s'avère indispensable pour accéder au moment angulaire des quarks. La première expérience dédiée au DVCS sur le neutron a eu lieu fin 2004 au Hall A du Jefferson Lab. La haute luminosité de l'expérience et le taux de bruit de fond qui en découle ont nécessité le développement d'équipements spécifiques qui sont décrits. Les méthodes d'analyse utilisées sont présentées et les résultats de l'expérience conduisant à des contraintes préliminaires sur la GPD E sont discutés.

Published
2006

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