614 research outputs found
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 photoproduction
Assuming that the photoproduction at forward angles and high
energies is dominated by one pion exchange we calculate the mass
distributions for low partial waves. Predictions of the model agree well
Assuming that the photoproduction at forward angles and high
energies is dominated by one pion exchange we calculate the mass
distributions for low partial waves. Predictions of the model agree well with
the experimental data which indicate that the , and waves are
dominated by the , and , 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
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