Processes of heavy quark production at HERA, TEVATRON and THERA energies are considered using the semihard ($k_T$ factorization) QCD approach with emphasis on the BFKL dynamics of gluon distributions.
Studies of charm and beauty production in ep collisions with a center-of-mass energy of 318 GeV are reported from the two HERA collaborations, H1 and ZEUS. The analyses make use of both the HERA-I data sample recorded between 1996 and 2000 and a samp
le from HERA-II, which started in 2003. The cross sections measured by both H1 and ZEUS experiments are compared with next-to-leading order QCD calculations. The measurement of the charm and beauty contributions to the proton structure function is also presented. The comparison to next-to-next-to-leading order (NNLO) calculations shows agreement within the errors.
Recent results from the experiments ZEUS and H1 on charm production in $ep$ collisions are reviewed. The topics are elastic and inelastic $J/psi$ photoproduction, $D^*$ photoproduction differential cross sections and a first look at the proton structure function F_2^{cbar{c}}.
We analyze the properties of the ACOT scheme for heavy quark production and make use of the MS-Bar massless results at NNLO and N3LO for the structure functions F2 and FL in neutral current deep-inelastic scattering to estimate the higher order corre
ctions. The dominant heavy quark mass effects at higher orders can be taken into account using the massless Wilson coefficients together with an appropriate slow-rescaling prescription implementing the phase space constraints. Combining the exact ACOT scheme at NLO with these expressions should provide a good approximation to the full calculation in the ACOT scheme at NNLO and N3LO.
We compute the structure functions F2 and FL in the ACOT scheme for heavy quark production. We use the complete ACOT results to NLO, and make use of the MSbar massless results at NNLO and N3LO to estimate the higher order mass-dependent corrections.
We show numerically that the dominant heavy quark mass effects can be taken into account using massless Wilson coefficients together with an appropriate rescaling prescription. Combining the exact NLO ACOT scheme with these expressions should provide a good approximation to the full calculation in the ACOT scheme at NNLO and N3LO.
Photoproduction of beauty and charm quarks in events with at least two jets has been measured with the ZEUS detector at HERA using an integrated luminosity of 133 $pb^{-1}$. The fractions of jets containing b and c quarks were extracted using the inv
ariant mass of charged tracks associated with secondary vertices and the decay-length significance of these vertices. Differential cross sections as a function of jet transverse momentum, $p_{T}^{text{jet}}$, and pseudorapidity, $eta^{text{jet}}$, were measured. The data are compared with previous measurements and are well described by next-to-leading-order QCD predictions.
S.P. Baranov
,A.V. Lipatov
,N.P. Zotovn (Skobeltsyn Institute of Nuclear Physics
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(2001)
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"Heavy Quark Production in the Semihard QCD Approach at HERA and Beyond"
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Nikolai Zotov
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