Speaker
Description
Progress is reported with a phenomenological analysis in full view of chromodynamics of a plausible Bethe-Heitler-like approach to measurements of exclusive elastic and dissociative electroproduction cross sections for vector-meson (VM) “quarkonia” of different flavour, namely ?\rho(760), u ubar - d dbar, \phi(??1019) s sbar, J\psi?(3096) c cbar and \Upsilon(??9460) b bbar? . First results are presented in the form of acceptable fits to measurements made by the H1 and Zeus experiments at the HERA electron-proton collider of the cross sections. The Bethe-Heitler-like hypothesis includes the factorisable, flavor-dependent,
combination of quark-antiquark contributions which describe measurements of real and virtual photon structure (??F_2^{\gamma*}), together with the appropriate, and universal, Regge-asymptotic form for flavour-blind, elastic, quark-proton (?qp) scattering which is based analyticity and on measurements
of the proton structure function F_2?? at appropriate Bjørken–x. The measurements are well described with constituent masses of u, d, s, c and b quarks and flavour-blind qp? scattering for which the Regge-asymptotic expansion is truncated at one leading pole with intercept consistent with that which tradition demands is called a “pomeron” and which depends on the “length” of elastic ?scattering. The pomeron is thus seen both to be at work at a scale which is below that of the interacting proton, that is of confinement, and, provided that account is taken of the “length” of ?scattering, to be universal.
