Studying the Proton "Radius" Puzzle with μp Elastic Scattering

Gilman, R.; Downie, E. J.; Ron, G.; Afanasev, A.; Arrington, J.; Ates, O.; Benmokhtar, F.; Bernauer, J. C.; Brash, Edward; Briscoe, W. J.; Deiters, K.; Diefenbach, J.; Djalali, C.; Dongwi, B.; Fassi, L. El; Gilad, S.; Gnanvo, K.; Gothe, R.; Higinbotham, D.; Holt, R. J.; Ilieva, Y.; Jiang, H.; Köhl, M.; Kumbartzki, G.; Lichtenstadt, J.; Liyanage, A.; Liyanage, N.; Meziane, M.; Meziani, Zein‐Eddine; Middleton, D. G.; Myers, K. E.; Perdrisat, C. F.; Piasetzsky, E.; Punjabi, V.; Ransome, R.; Reggiani, D.; Reimer, P.; Richter, A.; Sarty, A. J.; Schulte, E.; Shamai, Y.; Sparveris, N.; Strauch, S.; Sulkosky, V.; Tadepalli, A. S.; Taragin, M. F.; Weinstein, L. B.

doi:10.48550/arxiv.1303.2160

Cited by 51 publications

(74 citation statements)

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“…The next lightest meson is scalar σ(500). Its contribution was estimated to be about 0.1% in kinematics of MUSE experiment [74]. It was also found that the contribution of the triangle diagram strongly grows at Q 2 → 0.…”

Section: Triangle Diagrammentioning

confidence: 87%

“…This so-called "proton radius puzzle" gave rise to speculations whether there is some peculiarity in the muon electromagnetic interaction, or the discrepancy is just the result of poor consistency of scattering approach. To explore the former possibility, a muon-proton scattering experiments were proposed [74], which, in turn, called for estimate of TPE effects in muon-proton scattering, discussed in Sec.9.1.…”

Section: Low Q 2 and Proton Radiusmentioning

confidence: 99%

“…After discovery of the proton radius puzzle, one of the possible explanations was that the e.m. interaction of the muon is in some way different from that of the electron. To test this possibility, it was proposed to measure proton e.m. radius in the scattering approach, but with the muon beam [74].…”

Section: Muon-proton Scatteringmentioning

confidence: 99%

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Two photon exchange in elastic electron scattering off hadronic systems

Borisyuk,

Kobushkin

2019

Preprint

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In the present review we discuss different aspects of the two-photon exchange (TPE) physics in elastic ep scattering, at high Q 2 as well as at low Q 2 .The imaginary part of the TPE amplitude gives rise to beam and target single-spin asymmetries. Different theoretical approaches to calculation of these observables are considered. The real part of the TPE amplitude influence unpolarized cross section and double-spin observables and is, most likely, responsible for discrepancy between two methods of proton form factors measurements.We review different methods of calculations of the TPE amplitudes the framework of "hadron" and "quark-gluon" approaches. We discuss the dispersion approach suitable for low and intermediate Q 2 , which includes elastic and inelastic intermediate hadronic states, as well as connection of TPE to proton radius puzzle.The present situation with direct experimental searches for the TPE amplitude in e + p/e − p charge asymmetry is also discussed, as well as attempts to extract the TPE amplitudes from existing experimental data obtained by the Rosenbluth and double polarization techniques.The TPE physics in other processes, such as elastic µp, e-nucleus and eπ scattering is also reviewed.

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Section: Triangle Diagrammentioning

confidence: 87%

Section: Low Q 2 and Proton Radiusmentioning

confidence: 99%

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Two photon exchange in elastic electron scattering off hadronic systems

Borisyuk,

Kobushkin

2019

Preprint

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“…The muonic hydrogen spectroscopic results on the proton charge radius (Antognini et al, 2013a;Pohl et al, 2010) also motivated lepton-proton scattering measurements with muon beams. The MUon proton Scattering Experiment (MUSE) (Gilman et al, 2013(Gilman et al, , 2017 at PSI is currently ongoing in which measurements of leptonproton elastic scattering cross sections utilizing both the µ + and µ − (muon) beams will be compared to those performed with electron and positron beams. The MUSE experiment uses the PSI πM 1 beam line with e ± , and µ ± beams at incident momentum values of 115, 153 and 210 MeV/c to allow for simultaneous measurements of the µ ± p and e ± p elastic scattering cross sections.…”

Section: A the Muse Experiments At Psimentioning

confidence: 99%

The proton charge radius

Gao,

Vanderhaeghen

2021

Preprint

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Nucleons (protons and neutrons) are the building blocks of atomic nuclei, and are responsible for more than 99% of the visible matter in the universe. Despite decades of efforts in studying its internal structure, there are still a number of puzzles surrounding the proton such as its spin, and charge radius. Accurate knowledge about the proton charge radius is not only essential for understanding how quantum chromodynamics (QCD) works in the non-perturbative region, but also important for bound state quantum electrodynamics (QED) calculations of atomic energy levels. It also has an impact on the Rydberg constant, one of the most precisely measured fundamental constants in nature. This article reviews the latest situation concerning the proton charge radius in light of the new experimental results from both atomic hydrogen spectroscopy and electron scattering measurements, with particular focus on the latter. We also present the related theoretical developments and backgrounds concerning the determination of the proton charge radius using different experimental techniques. We discuss upcoming experiments, and briefly mention the deuteron charge radius puzzle at the end. CONTENTS I. Introduction 1 II. The Proton Charge Radius Puzzle 3 A. Before the millennium 3 B. After the millennium 3 III. Elastic Electron-Proton Scattering 3 A. Introduction to Electron-Proton Scattering and Proton Electromagnetic Form Factors 3 B. Three-dimensional parton distributions 5 C. The nucleon transverse charge densities 7 D. GPDs and quark densities in longitudinal momentum and transverse position in a proton 10 E. Radii of quark distributions in a proton 12 F. Unpolarized electron-proton elastic scattering 16 G. Double-Polarization Elastic Electron-Proton Scattering 17 1. Spin-Dependent Asymmetry from p( e, e )p 17 2. Recoil Proton Polarization from p( e, e p) 18 H. Two-Photon-Exchange Contribution to Electron-Proton Scattering 18 I. Radiative Corrections in Electron Scattering 20 J. The Extraction of the Proton Charge Radius from Proton Electric Form Factor 21 IV. Atomic Hydrogen Spectroscopy 21 V. Modern lepton scattering experiments 24 A. Mainz 2010 24 B. JLab recoil polarization experiment 24 C. Mainz ISR measurements 24 D. The PRad experiment at JLab 25 E. Proton charge radius from modern analyses of proton electric form factor data 29 VI. Modern spectroscopic measurements 31 A. Muonic hydrogen spectroscopic experiments 31 B. Ordinary Hydrogen spectroscopic experiments 33 VII. Ongoing and upcoming experiments 35 A. The MUSE experiment at PSI 35 B. The COMPASS++/AMBER Experiment at CERN 35 C. The PRad-II experiment at Jefferson Lab 36 D. Future electron scattering experiments at Mainz 38 E. The ULQ 2 experiment at Tohoku University 39 VIII. The deuteron charge radius 39 IX. Conclusions 42 X. Acknowledgments 42 References 43

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“…This paper deals with the neutron form factor which is experimentally not very well known but new precision measurements of this quantity are planned or presently being performed [2,3,4,5,6,7,8,9,10,11,12,13,14]. Because there are no free neutron targets the neutron form factor is determined from electron scattering on the deuteron.…”

Section: Introductionmentioning

confidence: 99%

Untitled

2020

Sohag J. Sci

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We extract a new value b = 0.0205 ± 0.0017 fm 2 of the slope of the neutron form factor G En (q 2 ) at q 2 = 0 compatible with deuteron properties by using a linear relation between b and A 2 S (1 + η 2 ) we found for a class of nonlocal potential models having the experimental values of both r D and Q. Another model dependent value b MHKZ = 0.0206 ± 0.0014 fm 2 , which is also compatible with deuteron properties, has been determined by applying "constrained" unitary transformations to the local MHKZ potential model. The sensitivity of a small changes in the experimental values used for r D and Q on the value obtained for b is also investigated.

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Studying the Proton "Radius" Puzzle with μp Elastic Scattering

Cited by 51 publications

References 0 publications

Two photon exchange in elastic electron scattering off hadronic systems

Two photon exchange in elastic electron scattering off hadronic systems

The proton charge radius

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