180 research outputs found
Intrinsic Charm In Proton and Photoproduction at High Energies
Based on a perturbative theory of quantum chromodynamics and non-relativistic
quark model, associated plus open charm photoproduction on charm
quarks in a proton via partonic subprocess 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 the contribution of the
subprocess in the inelastic 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 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
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.
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