Radiative corrections to electron-proton scattering

Abstract

The radiative corrections to elastic electron-proton scattering are analyzed in a hadronic model including the finite size of the nucleon. For initial electron energies above 8 GeV and large scattering angles, the proton vertex correction in this model increases by at least 2% of the overall factor by which the one-photon exchange cross section must be multiplied. In addition, we refine the mathematical treatment, removing many of the approximations made in the generally used expressions previously obtained by Mo and Tsai. In particular, the contribution of soft photon emission is calculated exactly. Results are presented for some kinematics at high momentum transfer and compared with the expressions of Mo and Tsai.

Nucleon electromagnetic form factors

“…Furthermore, in the references [Tsa61, MoT69, Tsa71] the effect of the structure of the nucleon was ignored, and a number of approximations were made. In more recent work on radiative corrections, Maximon and Tjon [Max00] have included the structure of the proton by introducing the proton FF, and they also eliminated some of the soft-photon approximations made by [Tsa61,MoT69,Tsa71]. In the current energy range of JLab, the difference for δ, the radiative correction, used in dσ dΩ = (1 + δ) dσ Born dΩ up to corrections of order α 3 , between the older and the new calculation is at the level of several %.…”

“…More recently Maximon and Tjon [Max00] have reconsidered the radiative correction calculation, and included additional terms with explicit emphasis of the hadronic effects. A similar reexamination of the MoTsai procedure was made by Vanderhaeghen et al [Vdh00] in the process of a detailed calculation of radiative corrections for virtual Compton (VCS).…”

Effective field theory for large logarithms in radiative corrections to electron proton scattering

“…The separation of soft and hard scales in two photon exchange is similarly ambiguous in standard treatments. The common MaximonTjon convention [40] implicitly takes momentum-dependent factorization scale µ 2 = Q 2 for two-photon exchange, in conflict with the Q 2 -independent choice µ 2 = M 2 that is closest to the implicit convention for vertex corrections.…”

“…[6] is essentially that of Maximon and Tjon [40], but neglecting an additional model-dependent correction (referred to as δ (1) el in Ref. [40]),…”

Complete experiment in e∓N-elastic scattering, in presence of two-photon exchange

“…The important point here is the calculation of radiative corrections to the differential cross section and to polarization observables in elastic eN -scattering. If these corrections are large (in absolute value) for the differential cross section [12], in particular for high resolution experiments, a simplified estimation of radiative corrections to polarization phenomena [13] shows that radiative corrections are small for the ratio P L /P T of longitudinal to transverse polarization of the proton emitted in the elastic collision of polarized electrons with an unpolarized proton target.…”