Nucleon Compton Scattering With Two Space–like Photons

Afanasev, Andrei; Akushevich, Igor; Merenkov, N. P.

doi:10.1142/9789812776211_0018

Cited by 37 publications

(76 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The approach of Ref. [14] consisted of taking only one amplitude for elastic doubly VCS, the one that survives in the exact forward RCS. It therefore amounts to neglecting not only the additional t dependence of the Compton amplitude but also the dependence on the photon virtualities.…”

Section: Resultsmentioning

confidence: 99%

“…At present, several experimental data points exist in different kinematical regimes [8]. On the theoretical side, significant progress has been made toward quantitative understanding of the experimental data [9]. * Electronic addrsss: gorshtey@caltech.edu These experimental and theoretical studies require a description of Compton scattering with two virtual photons.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Doubly virtual Compton scattering and the beam normal spin asymmetry

Gorchtein

2006

Phys. Rev. C

View full text Add to dashboard Cite

We construct an invariant basis for Compton scattering with two virtual photons (VVCS). The basis tensors are chosen to be gauge invariant and orthogonal to each other. The properties of the corresponding 18 invariant amplitudes are studied in detail. We consider the special case of elastic VVCS with the virtualities of the initial and final photons equal. The invariant basis for VVCS in this orthogonal form does not exist in the literature. We furthermore use this VVCS tensor for a calculation of the beam normal spin asymmetry in the forward kinematics. For this, we relate the invariant amplitudes to the helicity amplitudes of the VVCS reaction. The imaginary parts of the latter are related to the inclusive cross section by means of the optical theorem. We use the phenomenological value of the transverse cross section σ T ∼ 0.1 mb and the Callan-Gross relation which relates the longitudinal cross section σ L to the transverse one. The result of the calculation agrees with an existing calculation, and predicts negative values of the asymmetry B n of order of 5 ppm in the energy range from 3 to 45 GeV and for very forward angles.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Doubly virtual Compton scattering and the beam normal spin asymmetry

Gorchtein

2006

Phys. Rev. C

View full text Add to dashboard Cite

show abstract

“…[8] and found it to be highly suppressed compared to the inelastic excitations. For the kinematics of SLAC E158 [13], this suppression is a few orders of magnitude due to different angular and energy behavior of these contributions.…”

Section: Numerical Results and Discussionmentioning

confidence: 99%

Large logarithms in the beam normal spin asymmetry of elastic electron-proton scattering

Afanasev

Merenkov

2004

Phys. Rev. D

Self Cite

View full text Add to dashboard Cite

We study a parity-conserving single-spin beam asymmetry of elastic electron-proton scattering induced by an absorptive part of the two-photon exchange amplitude. It is demonstrated that excitation of inelastic hadronic intermediate states by the consecutive exchange of two photons leads to logarithmic and double-logarithmic enhancement due to contributions of hard collinear quasi-real photons. The asymmetry at small electron scattering angles is expressed in terms of the total photoproduction cross section on the proton, and is predicted to reach the magnitude of 20-30 parts per million. At these conditions and fixed 4-momentum transfers, the asymmetry is rising logarithmically with increasing electron beam energy, following the high-energy diffractive behavior of total photoproduction cross section on the proton.

show abstract

“…A comparison with our computation indicates that the preliminary experimental values for forward angle scattering and higher energies are substantially larger in magnitude than we are able to obtain via the low-energy expansion to O͑E / M͒ 2 . Presumably, a resummation of higher-order contributions in E / M using nonperturbative techniques, such as dispersion relations, would be required to compute reliably A n in this domain [12,[27][28][29][30]. We would also expect that inclusion of nucleon resonances 5 and pions as explicit degrees of freedom would be needed to account for the experimental results.…”

Section: Resultsmentioning

confidence: 99%

Vector analyzing power in elastic electron-proton scattering

Diaconescu

Ramsey-Musolf

2004

Phys. Rev. C

View full text Add to dashboard Cite

We compute the vector analyzing power (VAP) for the elastic scattering of transversely polarized electrons from protons at low energies using an effective theory of electrons, protons, and photons. We study all contributions through second order in E / M, where E and M are the electron energy and nucleon mass, respectively. The leading-order VAP arises from the imaginary part of the interference of one-and two-photon exchange amplitudes. Subleading contributions are generated by the nucleon magnetic moment and charge radius as well as recoil corrections to the leading-order amplitude. Working to O͑E / M͒ 2 , we obtain a prediction for A n that is free of unknown parameters and that agrees with the recent measurement of the VAP in backward angle ep scattering.

show abstract

Nucleon Compton Scattering With Two Space–like Photons

Cited by 37 publications

References 7 publications

Doubly virtual Compton scattering and the beam normal spin asymmetry

Doubly virtual Compton scattering and the beam normal spin asymmetry

Large logarithms in the beam normal spin asymmetry of elastic electron-proton scattering

Vector analyzing power in elastic electron-proton scattering

Contact Info

Product

Resources

About