Towards a Resolution of the Proton Form Factor Problem: New Electron and Positron Scattering Data

Adikaram, D.; Rimal, D.; Lb, Weinstein; Raue, B. A.; Khetarpal, P.; Rp, Bennett; Arrington, J.; Wk, Brooks; Kp, Adhikari; Afanasev, A.; Mj, Amaryan; Anderson,; S, Anefalos Pereira; Avakian, H.; Ball, J.; Battaglieri, M.; Bedlinskiy, I.; As, Biselli; Bono, J.; Boiarinov, S.; Briscoe, W. J.; Vd, Burkert; Ds, Carman; Careccia, S. L.; Celentano, A.; Chandavar, S.; Charles, G.; Colaneri, L.; Cole, P. L.; Contalbrigo, M.; Crede,; D’Angelo, A.; Dashyan, N.; R, De Vita; E, De Sanctis; Deur, A.; Djalali, C.; Ge, Dodge; Dupré, R.; Egiyan, H.; A, El Alaoui; L, El Fassi; Elouadrhiri, L.; Eugenio, P.; Fedotov, G.; Fegan, S.; Filippi, A.; Ja, Fleming; Fradi, A.; Garillon, B.; Gp, Gilfoyle; Kl, Giovanetti; Fx, Girod; Jt, Goetz; Gohn, W.; Golovatch, E.; Rw, Gothe; Griffioen, K. A.; Guegan, B.; Guidal, M.; Guo, L.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Harrison, N.; Hattawy, M.; Hicks, K.; Holtrop, M.; Sm, Hughes; Hyde‐Wright, C. E.; Ilieva, Y.; Ireland, D. G.; Bs, Ishkhanov; Jenkins, David; Jiang, Hao; Hs, Jo; Joo, K.; Joosten, S.; Kalantarians, N.; Keller, D.; Khandaker, M.; A, Kim; Kim, Won‐Seok; Klein, A.; Fj, Klein; Koirala, S.; Kubarovsky,; Se, Kuhn; Livingston, K.; Lu, Haojie; MacGregor, I. J. D.; Markov, N.; Mattione, P.; Mayer, Martin; McKinnon, B.; Mestayer,; Meyer, C. A.; Mirazita, M.; Mokeev,; Ra, Montgomery; Ci, Moody; Moutarde, H.; Movsisyan, A.; Cm, Camacho; Nadel-Turoński, P.; Niccolai, S.; Niculescu, G.; Osipenko, M.; Ai, Ostrovidov; K, Park; Pasyuk, E.; Peña, C.; Pisano, S.; Pogorelko, O.; Jw, Price; Procureur, S.; Prok, Y.; Protopopescu, D.; Aj, Puckett; Ripani, M.; Rizzo, A.; Rosner, G.; Rossi, P.; Roy, P.; Sabatié, F.; Salgado, C.; Schott, D.; Schumacher, R. A.; Seder, E.; Yg, Sharabian; Simonyan, A.; Skorodumina, Iu.; Es, Smith; Gd, Smith; Di, Sober; Sokhan, D.; Sparveris, N.; Stepanyan, S.; Stoler, P.; Strauch, S.; Sytnik,; Taiuti, M.; Tian, Ye; Trivedi, A.; Ungaro, M.; Voskanyan, H.; Voutier, E.; Nk, Walford; Dp, Watts; Wei, Xin; Mh, Wood; Zachariou, N.; Zana, L.; Zhang, J; Zhao, Zhi-hui; Zonta, I.

doi:10.1103/physrevlett.114.062003

Cited by 93 publications

(69 citation statements)

References 47 publications

(32 reference statements)

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“…In summary, most of these studies can explain parts of the difference in terms of TPE effects, although the precise interplay between hadronic and partonic effects remains an open question. To this end, the ratio of the elastic e + p/e − p cross sections has been measured by several experiments to provide a definitive test of the magnitude of TPE effects [667][668][669][670].…”

Section: Overview Of Two-photon Physicsmentioning

confidence: 99%

Baryons as relativistic three-quark bound states

Eichmann

Sanchis-Alepuz

Williams

et al. 2016

Progress in Particle and Nuclear Physics

406

530

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We review the spectrum and electromagnetic properties of baryons described as relativistic three-quark bound states within QCD. The composite nature of baryons results in a rich excitation spectrum, whilst leading to highly non-trivial structural properties explored by the coupling to external (electromagnetic and other) currents. Both present many unsolved problems despite decades of experimental and theoretical research. We discuss the progress in these fields from a theoretical perspective, focusing on nonperturbative QCD as encoded in the functional approach via Dyson-Schwinger and Bethe-Salpeter equations. We give a systematic overview as to how results are obtained in this framework and explain technical connections to lattice QCD. We also discuss the mutual relations to the quark model, which still serves as a reference to distinguish 'expected' from 'unexpected' physics. We confront recent results on the spectrum of non-strange and strange baryons, their form factors and the issues of two-photon processes and Compton scattering determined in the DysonSchwinger framework with those of lattice QCD and the available experimental data. The general aim is to identify the underlying physical mechanisms behind the plethora of observable phenomena in terms of the underlying quark and gluon degrees of freedom.

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Section: Overview Of Two-photon Physicsmentioning

confidence: 99%

Baryons as relativistic three-quark bound states

Eichmann

Sanchis-Alepuz

Williams

et al. 2016

Progress in Particle and Nuclear Physics

406

530

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show abstract

“…At Q 2 above 1 GeV 2 , determinations of the form factor ratio from unpolarised and polarised measurement do not agree. This has been attributed to two-photon exchange, whose size is directly tested in current experiments [39][40][41]. At lower Q 2 , this effect is believed to be small, but could explain part of the proton ratio discrepancy.…”

mentioning

confidence: 80%

PERLE. Powerful energy recovery linac for experiments. Conceptual design report

Angal-Kalinin

Arduini

Auchmann

et al. 2018

J. Phys. G: Nucl. Part. Phys.

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A conceptual design is presented of a novel energy-recovering linac (ERL) facility for the development and application of the energy recovery technique to linear electron accelerators in the multi-turn, large current and large energy regime. The main characteristics of the powerful energy recovery linac experiment facility (PERLE) are derived from the design of the Large Hadron electron Collider, an electron beam upgrade under study for the LHC, for which it would be the key 11 Author to whom any correspondence should be addressed.Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. demonstrator. PERLE is thus projected as a facility to investigate efficient, high current (HC) (>10 mA) ERL operation with three re-circulation passages through newly designed SCRF cavities, at 801.58 MHz frequency, and following deceleration over another three re-circulations. In its fully equipped configuration, PERLE provides an electron beam of approximately 1 GeV energy. A physics programme possibly associated with PERLE is sketched, consisting of high precision elastic electron-proton scattering experiments, as well as photo-nuclear reactions of unprecedented intensities with up to 30 MeV photon beam energy as may be obtained using Fabry-Perot cavities. The facility has further applications as a general technology test bed that can investigate and validate novel superconducting magnets (beam induced quench tests) and superconducting RF structures (structure tests with HC beams, beam loading and transients). Besides a chapter on operation aspects, the report contains detailed considerations on the choices for the SCRF structure, optics and lattice design, solutions for arc magnets, source and injector and on further essential components. A suitable configuration derived from the here presented design concept may next be moved forward to a technical design and possibly be built by an international collaboration which is being established.

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“…for electron-proton elastic scattering at high Q 2 [40][41][42][43], calculations and recent data suggest that they are typically below 1% for elastic scattering at the Q 2 values of this measurement [40,[44][45][46][47]. Estimates of the TPE contribution to resonance production [48,49] suggest that the corrections for the resonance region are smaller than those for elastic scattering by roughly a factor of 2 for production.…”

Section: Discussionmentioning

confidence: 99%

Measurements of the separated longitudinal structure function FL from hydrogen and deuterium targets at low Q2

Tvaskis¹,

Tvaskis²,

Niculescu³

et al. 2018

Phys. Rev. C

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Structure functions, as measured in lepton-nucleon scattering, have proven to be very useful in studying the partonic dynamics within the nucleon. However, it is experimentally difficult to separately determine the longitudinal and transverse structure functions, and consequently there are substantially less data available in particular for the longitudinal structure function. Here, we present separated structure functions for hydrogen and deuterium at low four-momentum transfer squared, Q 2 < 1 GeV 2 , and compare them with parton distribution parametrization and k T factorization approaches. While differences are found, the parametrizations generally agree with the data, even at the very low-Q 2 scale of the data. The deuterium data show a smaller longitudinal structure function and a smaller ratio of longitudinal to transverse cross section, R, than the proton. This suggests 2469-9985/2018/97(4)/045204 (11) 045204-1 ©2018 American Physical Society V. TVASKIS et al.PHYSICAL REVIEW C 97, 045204 (2018) either an unexpected difference in R for the proton and the neutron or a suppression of the gluonic distribution in nuclei.

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Towards a Resolution of the Proton Form Factor Problem: New Electron and Positron Scattering Data

Cited by 93 publications

References 47 publications

Baryons as relativistic three-quark bound states

Baryons as relativistic three-quark bound states

PERLE. Powerful energy recovery linac for experiments. Conceptual design report

Measurements of the separated longitudinal structure function FL from hydrogen and deuterium targets at low Q2

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