Related papers: Nucleon Polarizibilities for Virtual Photons
In the confinement regime at Q^2=0 the Gerasimov-Drell-Hearn (GDH) Sum Rule connects static properties of the nucleon with the difference of spin dependent doubly polarized total absorption cross sections of real photons. Now, for the first…
We calculate the spin-dependent polarizability of the nucleon in the Skyrme model. The result is compared with that of a heavy baryon chiral perturbation theory(HBChPT), and is shown to be the same as that of HBChPT up to the $\Delta$-pole…
We extend the recently developed formalism to extract light-front quark charge densities from nucleon form factor data to the deformations of these quark charge densities when applying an external electric field. We show that the resulting…
In addition to the E2/M1 ratio of the N->$\Delta$ transition, the electromagnetic polarizabilities and spin-polarizabilities are important structure constants of the nucleon which serve as sensitive tests of chiral perturbation theory and…
We present a physical model for polarized and unpolarized structure functions and parton density functions (PDFs) of the proton and the neutron. It reproduces the data on F_2^p(x,Q^2) for 0.00001<x<1 and 2.5<Q^2<5000 GeV^2,…
A phenomenological parameterization of the proton polarized structure function has been developed for x > 0.02 using deep inelastic data up to ~ 50 (GeV/c)**2 as well as available experimental results on both photo- and electro-production…
We compute various nucleon polarizabilities in chiral perturbation theory implementing the $\Delta$-full ($\Delta$-less) approach up to order $\epsilon^3 + q^4$ ($q^4$) in the small-scale (chiral) expansion. The calculation is carried out…
Spin-dependent parton distributions in the polarized virtual photon are investigated in QCD up to the next-to-leading order (NLO). In the case $\Lambda^2 \ll P^2 \ll Q^2$, where $-Q^2$ ($-P^2$) is the mass squared of the probe (target)…
Previous representations of pion pair production amplitudes by two real photons at low energy, which combine dispersion theoretical constraints with elastic unitariy, chiral symmetry and soft photon constraints are generalized to the case…
We examine the $Q^2$ evolution of gluon polarization in polarized nucleons. As is well known, the evolution of $\alpha_s \Delta G(Q^2)$ is negligible for typical momentum transfer variations found in experimental deep inelastic scattering.…
Recent measurements of unpolarised and polarised nucleon structure functions and F_2(gamma) are reviewed. The implications for QCD and the gluon momentum distribution are discussed. The status of the understanding of the total…
We have measured proton and deuteron virtual photon-nucleon asymmetries A2p and A2d and structure functions g2p and g2d over the range 0.03<x<0.8 and 1.3<Q2<10 (GeV/c)2 by inelastically scattering polarized electrons off polarized ammonia…
The QCD hardness scale for secondary particles ($h$) production in semi-inclusive deep inelastic scattering (DIS), $e p \to e' X h$, gradually decreases from $Q^{2}$, the photon virtuality which determines the hard scale in the virtual…
It is demonstrated that new JLAB proton polarization data, which are in a rather strong disagreement with the proton electric form factor data in the space-like region obtained by Rosenbluth technique, are consistent with all known form…
This talk consists of four parts. In part one, I give an elementary discussion on constructing a Lorentz-invariant spin sum rule for the nucleon. In part two, I discuss a gauge-dependent spin sum rule, explore its relation with the…
We utilize the generalized contact formalism in conjunction with the Woods-Saxon mean-field description of the long-range part of the nuclear wave function to assess the relative prevalence of short-range correlation pairs within atomic…
The small fraction of the quark polarization of the nucleon obtained in deep inelastic lepton scattering is a consequence of a wrong assumption on the flux of polarized virtual photons in the analysis of the data. The true flux of polarized…
We investigate the possibility to draw conclusions on the sign of the spin-dependent gluon distribution, $\Delta G(x, Q^2)$, from existing polarized DIS data. The spin-dependent parton distributions $\Delta u_v, \Delta d_v, \Delta {\bar u},…
We propose a unified new approach to describe polarized and unpolarized quark distributions in the proton based on the gauge-gravity correspondence, light-front holography, and the generalized Veneziano model. We find that the…
The contribution of virtual excitations to the energy levels of electronic and muonic hydrogen is investigated combining a model-independent approach for the main part with quark model predictions for the remaining corrections. Precise…