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

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.

Inclusive b and b anti-b production with quasi-multi-Regge kinematics at the Tevatron

We consider b-jet hadroproduction in the quasi-multi-Regge-kinematics approach based on the hypothesis of gluon and quark Reggeization in t-channel exchanges at high energies. The preliminary data on inclusive b-jet and b anti-b-dijet production taken by the CDF Collaboration at the Fermilab Tevatron are well described without adjusting parameters. We find the main contribution to inclusive b-jet production to be the scattering of a Reggeized gluon and a Reggeized b-quark to a b quark, which is described by the effective Reggeon-Reggeon-quark vertex. The main contribution to b anti-b-pair production arises from the scattering of two Reggeized gluons to a b anti-b pair, which is described by the effective Reggeon-Reggeon-quark-quark vertex. Our anaysis is based on the Kimber-Martin-Ryskin prescription for unintegrated gluon and quark distribution functions using as input the Martin-Roberts-Stirling-Thorne collinear parton distribution functions of the proton.Comment: 14 pages, 4 figures; formulas for effective vertices included, discussion of errors somewhat expanded; accepted for publication in Phys. Rev.