What is Measured in Hard Exclusive Electroproduction?

We examine the relation between amplitudes measured in exclusive lepto-production and the quark content of the nucleon. We show that in the limit of high energy and small t, the natural interpretation of amplitudes measured in these hard exclusive processes is in terms of the quark content of the meson cloud and not the target itself. In this regime, Regge amplitudes will make a significant contribution to these exclusive amplitudes. This leads to violation of QCD scaling.Comment: 6 pages, 2 figure

Constructing Confinement

The interaction between static quarks is derived by applying many-body techniques to QCD in Coulomb gauge. The result is shown to be exact in the IR and UV limits, and agrees remarkably well with lattice computations.Comment: 6 pages, 3 figures, proceedings for 2002 Lake Louise Winter Institut

Separation of Soft and Hard Physics in DVCS

A model for deeply virtual Compton scattering, based on analytical light-cone hadron wave functions is presented and studied at energies currently accessible at Jefferson Laboratory and DESY. It is shown that poles and perpendicular vector components play an important role at Q^2 < 10 GeV^2. A Q^2 suppressed diagram has to be included at these low energies, but becomes negligible above 10 GeV^2. Future prospects and developments of this model are discussed.Comment: 6 pages, 2 figures, uses ws-procs9x6.cls, to appear in Proceedings of the Exclusive Processes at High-t Workshop at Jefferson Lab, May 15-18 200

Meson resonances in forward-angle π+π−\pi^+\pi^- photoproduction

Assuming that the $\pi^+\pi^-$ photoproduction at forward angles and high energies is dominated by one pion exchange we calculate the $\pi^+\pi^-$ mass distributions for low partial waves. Predictions of the model agree well Assuming that the $\pi^+\pi^-$ photoproduction at forward angles and high energies is dominated by one pion exchange we calculate the $\pi^+\pi^-$ mass distributions for low partial waves. Predictions of the model agree well with the experimental data which indicate that the $S$, $P$ and $D$ waves are dominated by the $f_0(980)$, $\rho(770)$ and $f_2(1270)$, resonances respectively.Comment: 6 pages, 7 figure

Quark-nucleon dynamics and Deep Virtual Compton Scattering

We consider deeply virtual Compton scattering and deep inelastic scattering in presence of Regge exchanges that are part of the non-perturbative quark-nucleon amplitude. In particular we discuss contribution from the Pomeron exchange and demonstrate how it leads to Regge scaling of the Compton amplitude. Comparison with HERA data is given.Comment: 12 pages, 5 figure

Gluon chain formation in presence of static charges

We consider the origins of the gluon chain model. The model serves as a realization of the dynamics of the chromoelectric flux between static quark-antiquark sources. The derivation is based on the large-N_C limit of the Coulomb gauge Hamiltonian in the presence of a background field introduced to model magnetic confinement.Comment: 10 pages, 9 figure

Spontaneous chiral symmetry breaking in the linked cluster expansion

We investigate dynamical chiral symmetry breaking in the Coulomb gauge Hamiltonian QCD. Within the framework of the linked cluster expansion we extend the BCS ansatz for the vacuum and include correlation beyond the quark-antiquark paring. In particular we study the effects of the three-body correlations involving quark-antiquark and transverse gluons. The high momentum behavior of the resulting gap equation is discussed and numerical computation of the chiral symmetry breaking is presented.Comment: 13 pages, 9 figure