D. Marchand

QED radiative corrections to virtual Compton scattering

The QED radiative corrections to virtual Compton scattering (reaction

First determination of generalized polarizabilities of the proton by a virtual compton scattering experiment.

e p \to e p \gamma

Virtual Compton Scattering and polarizabilities

) are calculated to first order in

The first virtual Compton scattering experiment at MAMI

\alpha_{em} \equiv e^2 / 4 \pi

Virtual compton scattering under π0 threshold at Q2=0.33 GeV2. Preliminary results

. A detailed study is presented for the one-loop virtual corrections and for the first order soft-photon emission contributions. Furthermore, a full numerical calculation is given for the radiative tail, corresponding with photon emission processes, where the photon energy is not very small compared with the lepton momenta. We compare our results with existing works on elastic electron-proton scattering, and show for the

Virtual Compton Scattering at MAMI γ*p→ γ1p1

e p \to e p \gamma

The first dedicated virtual Compton scattering experiment at MAMI

reaction how the observables are modified due to these first order QED radiative corrections. We show results for both unpolarized and polarized observables of the virtual Compton scattering in the low energy region (where one is sensitive to the generalized polarizabilities of the nucleon), as well as for the deeply virtual Compton scattering.

Nucleon structure study by virtual Compton scattering

Absolute differential cross sections for the reaction (e+p ->e+p+gamma) have been measured at a four-momentum transfer with virtuality Q^2=0.33 GeV^2 and polarization \epsilon = 0.62 in the range 33.6 to 111.5 MeV/c for the momentum of the outgoing photon in the photon-proton center of mass frame. The experiment has been performed with the high resolution spectrometers at the Mainz Microtron MAMI. From the photon angular distributions, two structure functions which are a linear combination of the generalized polarizabilities have been determined for the first time.

Real and Virtual Compton Scattering and Polarizabilities.

Abstract Virtual Compton Scattering (VCS) off the proton below pion threshold allows access to generalized polarizabilities of the proton. These observables measure the response of the nucleon to low energy electromagnetic field perturbations. This paper presents a comparison with Real Compton Scattering and also results for the first dedicated VCS experiment performed at the Mainz Microtron MAMI with high resolution spectrometers at Q2 = 0.33 GeV2.

QED radiative corrections to virtual Compton scattering - art. no. 025501.

Abstract Virtual Compton scattering, i.e. the exclusive reaction γ ∗ p → γ′p′ with γ ∗ denoting a virtual photon, provides new insights on the internal structure of the proton. Below π 0 production threshold, this experiment measures the generalized polarizabilities of the proton as defined by Guichon et al [1], [2] and Drechsel et al [3]. These new electromagnetic observables, functions of Q 2 , enlarge the concept of electric (α0 and magnetic (β) polarizabilities in Real Compton Scattering ( Q 2 =0) [4]. The first VCS experiment [5] of this kind was measured at the three spectrometer facility at the Mainz Microtron MAMI for Q 2 =0.33 GeV 2 and we present in this paper the preliminary results.