47 research outputs found
Lessons from Hadron Phenomenology
Meson spectra can be well approximated by a specific form of a nonlinear
Regge trajectory which is consistent with a finite number of bound states. This
may have important consequencies for experiment, and may be a hint for the
theory.Comment: talk presented by MB at the Light-Cone Meeting in Heidelberg, June
2000. To appear in the proceedings, requires elsart.cls. 4 page
The Spin and Flavour Dependence of High-Energy Photoabsorption
We review the present data on high-energy, spin-dependent photoabsorption. We
find a strong isotriplet term in which persists from
GeV to high polarised deep inelastic scattering. For
GeV and between 0.01 and 0.12 the isotriplet part of
behaves as , in contrast to soft Regge
theory which predicts that should converge as . The
isotriplet, polarised structure function is significantly
greater than the isotriplet, unpolarised structure function in
this kinematic region. We analyse the low photoabsorption data from E-143
and SMC and use this data to estimate the high-energy Regge contribution to the
Drell-Hearn-Gerasimov sum-rule.Comment: 19 pages, LaTeX, 3 figures generated as g1,g1F2 and A1.te
The Drell-Hearn-Gerasimov Sum-Rule at Polarized HERA
We discuss the potential of polarized HERA to measure the spin dependent part
of the total photoproduction cross-section at large .Comment: 7 pages, LaTeX, 1 figure generated as fig1.tex. To appear in Proc.
Workshop on ``Physics with Polarized Protons at HERA'
Quarkonia in Hamiltonian Light-Front QCD
A constituent parton picture of hadrons with logarithmic confinement
naturally arises in weak coupling light-front QCD. Confinement provides a mass
gap that allows the constituent picture to emerge. The effective renormalized
Hamiltonian is computed to , and used to study charmonium and
bottomonium. Radial and angular excitations can be used to fix the coupling
, the quark mass , and the cutoff . The resultant hyperfine
structure is very close to experiment.Comment: 9 pages, 1 latex figure included in the text. Published version (much
more reader-friendly); corrected error in self-energ
Small x divergences in the Similarity RG approach to LF QCD
We study small x divergences in boost invariant similarity renormalization
group approach to light-front QCD in a heavy quark-antiquark state. With the
boost invariance maintained, the infrared divergences do not cancel out in the
physical states, contrary to previous studies where boost invariance was
violated by a choice of a renormalization scale. This may be an indication that
the zero mode, or nontrivial light-cone vacuum structure, might be important
for recovering full Lorentz invariance.Comment: 23 pgs, 1 fig. Revised for publication: typos corrected, improved
discussion of regularizatio