Dispersion relation formalism for the two-photon exchange correction to elastic muon–proton scattering: elastic intermediate state

Tomalak, Oleksandr; Vanderhaeghen, Marc

doi:10.1140/epjc/s10052-018-5988-5

Cited by 29 publications

(15 citation statements)

References 77 publications

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“…This brought about a renaissance in TPE studies relating to the ℓp scattering process. A wide variety of hadronic model analyses of the TPE contributions include dispersion theory methods [35][36][37][38][39][40][41][42][43][44][45][46][47][48][49] 2 , resonance exchange models and dynamical coupled channel K-matrix analyses [50][51][52][53][54][55]. In these evaluations of the TPE processes, inelastic intermediate states of the nucleon and the ∆, namely, the N * , ∆ * and other possible excitation, 1 These charge-asymmetry measurements can not be used to extract the TPE contribution directly.…”

Section: Introductionmentioning

confidence: 99%

Lepton-proton two-photon exchange in chiral perturbation theory

et al. 2020

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We use heavy baryon chiral perturbation theory to evaluate the two-photon exchange corrections to the low-energy elastic lepton-proton scattering at next-to-leading order accuracy, i.e., O(α, M −1 ), including a non-zero lepton mass. We consider the elastic proton intermediate state in the two-photon exchange invoking soft photon approximation. The infrared singular contributions are projected out using dimensional regularization. The resulting infrared singularity-free two-photon exchange contribution is in good numerical agreement with existing predictions based on standard diagrammatic soft photon approximation evaluations.

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Section: Introductionmentioning

confidence: 99%

Lepton-proton two-photon exchange in chiral perturbation theory

et al. 2020

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“…Later, the same authors developed a dispersion formalism to calculate TPE amplitudes for the scattering [93,94]. It is worth to note that the calculation of the amplitude 4 requires a subtracted dispersion relation.…”

Section: Muon-proton Scatteringmentioning

confidence: 99%

Two-Photon Exchange in Elastic Electron Scattering on Hadronic Systems

Borisyuk

Kobushkin

2021

Ukr. J. Phys.

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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 Q2, as well as at low Q2. The imaginary part of the TPE amplitude gives rise to beam and target single-spin asymmetries. Different theoretical approaches to the calculation of these observables are considered. The real part of the TPE amplitude influences the unpolarized cross-section and double-spin observables and is, most likely, responsible for the discrepancy between two methods of measurements of the proton form factors. We review different methods of calculations of the TPE amplitudes in the framework of the “hadron” and “quark-gluon” approaches. We discuss the dispersion approach suitable for low and intermediate Q2, which includes elastic and inelastic intermediate hadronic states, as well as the connection of TPE with the proton radius puzzle. The present situation with direct experimental searches for the TPE amplitude in the 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 мp, e-nucleus, and еп scattering is also reviewed.

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“…Comparing (47) and (48) we see that the former has an explicit factor of m in the left hand side. This extra factor of m can be understood by looking at (40). All the spin-independent terms in (40) contain an explicit factor of m with the exception of the term proportional to 2iQx.…”

Section: Extraction Of Matching Coefficients For the Protonmentioning

confidence: 99%

“…This extra factor of m can be understood by looking at (40). All the spin-independent terms in (40) contain an explicit factor of m with the exception of the term proportional to 2iQx. Since this term multiplies W 1 which is an even function of x, we must combine it with 2imQx from the lepton propagator.…”

Section: Extraction Of Matching Coefficients For the Protonmentioning

confidence: 99%

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Elements of QED-NRQED effective field theory. II. Matching of contact interactions

2019

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In 2010 the first extraction of the proton charge radius from muonic hydrogen was found be five standard deviations away from the regular hydrogen value. Eight years later, this proton radius puzzle is still unresolved. One of the most promising avenues to resolve the puzzle is by a muon-proton scattering experiment called MUSE. The typical momenta of the muons in this experiment are of the order of the muon mass. In this energy regime the muons are relativistic but the protons are non-relativistic. The interaction between them can be described by QED-NRQED effective field theory. In a previous paper we have shown how QED-NRQED reproduces Rosenbluth scattering up to 1/M 2 , where M is the proton mass, and relativistic scattering off a static potential at O(Z 2 α 2 ) and leading power in M . In this paper we determine the Wilson coefficients of the fourfermion contact interactions at O(Z 2 α 2 ) and power 1/M 2 . Surprisingly, we find that the coefficient of the spin-independent interaction vanishes, implying that MUSE will be sensitive mostly to the proton charge radius and not spin-independent two-photon exchange effects.

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Dispersion relation formalism for the two-photon exchange correction to elastic muon–proton scattering: elastic intermediate state

Cited by 29 publications

References 77 publications

Lepton-proton two-photon exchange in chiral perturbation theory

Lepton-proton two-photon exchange in chiral perturbation theory

Two-Photon Exchange in Elastic Electron Scattering on Hadronic Systems

Elements of QED-NRQED effective field theory. II. Matching of contact interactions

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