Related papers: Nucleon Polarizibilities for Virtual Photons
In a previous paper virtual Compton scattering off the nucleon has been investigated in the one-loop approximation of the linear sigma model in order to determine the 3 scalar generalized polarizabilities. We have now extended this work and…
Virtual Compton scattering on the proton has been investigated at three yet unexplored values of the four-momentum transfer $Q^2$: 0.10, 0.20 and 0.45 GeV$^2$, at the Mainz Microtron. Fits performed using either the low-energy theorem or…
Using the techniques of chiral effective field theories we evaluate the so called generalized polarizabilities of the nucleon, which characterize the structure dependent components in virtual Compton scattering (VCS) as probed in the…
The spin structure of the nucleon is analyzed in the framework of a Lorentz-invariant formulation of baryon chiral perturbation theory. The structure functions of doubly virtual Compton scattering are calculated to one-loop accuracy (fourth…
Using a model for two pion photoproduction on the proton previously tested in total cross sections and invariant mass distributions, we evaluate here polarization observables on which recent experiments are providing new information. We…
These proceedings sketch how combining recent theoretical advances with data from the new generation of high-precision Compton scattering experiments on both the proton and few-nucleon systems offers fresh, detailed insight into the Physics…
Phenomenological parameterizations of proton and neutron polarized structure functions, g1p and g1n, are developed for x > 0.02 using deep inelastic data up to ~ 50 (GeV/c)**2 as well as available experimental results on photo- and…
We investigate the dependence of polarisation observables in elastic deuteron Compton scattering below the pion production threshold on the spin-independent and spin-dependent iso-scalar dipole polarisabilities of the nucleon. The…
With the use of pionless effective field theory including dibaryon fields, we study the $\gamma d \to \vec{n} p$ reaction for the laboratory photon energy $E_\gamma^{lab}$ ranging from threshold to 30 MeV. Our main goal is to calculate the…
We review recent developments in the theoretical investigation of the nucleon polarizabilities. We first report on the static polarizabilities as measured in real Compton scattering, comparing and interpreting the results from various…
The mean square polarizability radii of the proton have been measured for the first time in a virtual Compton scattering experiment performed at the MIT-Bates out-of-plane scattering facility. Response functions and polarizabilities…
Contents: 1. The sum rules or $\Gamma_{p,n}$.Theoretical status. 2. Calculations of matrix elements over the polarized nucleon by the QCD sum rule approach. 3. Twist-4 corrections to $\Gamma_{p,n}$ from QCD sum rules. 4. Gerasimov,…
We investigate the electric polarizabilities of neutral baryons using the method of QCD sum rules. The diagrams in the operator product expansion are taken into account up to dimension 6. We obtain different values of the polarizabilities…
The general structure of the cross section of $\gamma N$ scattering with polarized photon and/or nucleon in initial and/or final state is systematically described and exposed through invariant amplitudes. A low-energy expansion of the cross…
We calculate the $N^*$ contributions to the generalized polarizabilities of the proton in virtual Compton scattering. The following nucleon excitations are included: $N^*(1535)$, $N^*(1650)$, $N^*(1520)$, $N^*(1700)$, $\Delta(1232)$,…
The electromagnetic polarizabilities of the nucleon are shown to be essentially composed of the nonresonant $\alpha_p(E_{0+})=+3.2$, $\alpha_n(E_{0+})=+4.1$,the $t$-channel $\alpha^t_{p,n}=-\beta^t_{p,n}=+7.6$ and the resonant…
An analysis of all experimental data of 50's - 90's on elastic gamma-p scattering at photon energies below 150 MeV (10 experimental works) is performed in order to determine the electric (alpha_p) and magnetic (beta_p) polarizabilities of…
A scheme to calculate the electric spin polarizability of the neutron, based on a four-point function approach to the background field method, is presented. The connected contributions to this spin polarizability are evaluated within a…
The sum rule for the first moment of the polarised (virtual) photon structure function $g_1^\gamma(x,Q^2;K^2)$ is revisited in the light of proposals for future $e^+ e^-$ colliders. The sum rule exhibits an array of phenomena characteristic…
Using a novel analysis technique, the gluon polarisation in the nucleon is re-evaluated using the longitudinal double-spin asymmetry measured in the cross section of semi-inclusive single-hadron muoproduction with photon virtuality…