Charm Photoproduction At Large Transverse Momentum And The Charm Content Of The Photon

The charm quark photoproduction at large transverse momentum in the resolved photon interaction via partonic subprocess \cg is studied. It is shown that at HERA energies the contribution of the charm quark excitation in the photon in the inclusive charm production at \pt>5 GeV/c dominates over the other resolved photon contribution via the gluon content of the photon and it is about 30\% of the contribution of the $c\bar c$-pair production via the photon-gluon fusion mechanism.Comment: LaTeX, 4 pages, 4 figures are not include

Intrinsic Charm In Proton and J/ψJ/\psi Photoproduction at High Energies

Based on a perturbative theory of quantum chromodynamics and non-relativistic quark model, associated $J/\psi$ plus open charm photoproduction on charm quarks in a proton via partonic subprocess $\gamma c\to J/\psi c$ is discussed. It is shown that the value and energy dependence of the cross section for such process remarkably depends on the choice of charm distribution function in a proton. In the region of small $z=E_J/E_{\gamma}<0.2$ the contribution of the $\gamma c\to J/\psi c$ subprocess in the inelastic $J/\psi$ photoproduction spectra is larger than the contribution of the photon-gluon fusion subprocess. At the energy range of HERA collider intrinsic charm contribution in the total inclusive $J/\psi$ photoproduction cross section may be equal to 4\% of the dominant contribution of photon-gluon fusion mechanism.Comment: 11 pages, submitted to Mod.Phys.Lett.

Lambda_b polarization in the Z boson decays

In the framework of the perturbative QCD and the diquark model of baryons we have obtained the fragmentation functions for heavy quark that split into polarized Lambda_b baryons. We predict the longitudinal polarization asymmetry for the prompt Lambda_b produced in electron-positron annihilation at the Z resonance and estimate the spin-1/2 and spin-3/2 beauty baryon production rate.Comment: LaTeX, 8 pages plus 6 figures using psfig.st