OPE constraints are studied as a means of distinguishing between the versions of the I = 1 vector spectral function extracted from (i) inclusive I = 1 hadronic electroproduction cross-sections and (ii) inclusive I = 1 hadronic τ decay data, with the goal of clarifying expectations for the leading order hadronic contribution to aµ = (g − 2)µ/2 in the Standard Model. The constraints are shown to,...

In this thesis an analysis of diffractive J/ψ photoproduction and electroproduction in epcollisions is presented. The data were collected with the H1 detector and correspond to an integrated luminosity of 54.79pb−1. The kinematic range covers the region of 40GeV < W < 160GeV and −t < 1.2GeV, where W is the centre-of-mass energy in the photonproton system and −t is the squared four-momentum tran...

We report measurements of p” and $ electroproduction at 19.5 GeV in a wide-aperture spectrometer which detected the scattered electron and the decay products of the vector mesons. As Iq 2 I increases, the rho mass spectrum shape changes, the momentum transfer distribution broadens, and the ratio of the rho cross section to the total cross sec,“i tion decreases. The ratio of longitudinally to tr...

Electroproduction of rho mesons followed by decay . into two pions is’studied. Angular correlations between the pions and electrons are explicitly evaluated and shown to allow a separation of the longitudinal and transverse photon cross sections. (Submitted to Phys . Rev. ) * Work supported by the U.S. Atomic Energy Commission.

About possible influence of birefringence effect on processes of production (photoproduction, electroproduction) of vector mesons (particles with the spin S ≥ 1) in nuclei Abstract It is shown that birefringence effect influences on production of particles with the spin S ≥ 1 at collisions of high energy particles.

A simple semiquantitative picture of diffractive electroproduction is described. Although the diffractive component of F 2 is approximately independent of Q 2 and W 2 , this mechanism is " soft, " i.e. it depends upon large-distance physics and is not readily describable within perturbative QCD.

We show that hard electroproduction is a promising way to study exotic hybrid mesons, in particular through the hybrid decay channel H → πη. We discuss the πη generalized distribution amplitude, calculate the production amplitude and propose a forward-backward asymmetry as a signal for the hybrid meson production.

The leading and sub-leading order results for pion electroproduction in polarized and unpolarized semi-inclusive deep-inelastic scattering, are considered putting emphasis on transverse momentum dependent effects appearing in azimuthal asymmetries. In particular the spin-dependent (single, double) and spin-independent asymmetries of the distributions in the azimuthal angle φ of the pion related...

We introduce generalized quark and gluon distributions in the deuteron, which can be measured in exclusive processes like deeply virtual Compton scattering and meson electroproduction. We discuss the basic properties of these distributions and point out how they probe the interplay of nucleon and parton degrees of freedom in the deuteron wave function.

By means of an explicit one-loop calculation, it is shown that the leading twist contribution to the exclusive electroproduction of transversely polarized vector mesons from the nucleon vanishes. This confirms the all-orders proof by Collins and Diehl. Typeset using REVTEX Permanent Address: Department of Physics, Quaid-e-Azam University, Islamabad 45320, Pakistan