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N. P. Zotov

Publications and source records attributed to N. P. Zotov.

At least 55 records · Page 3Linked to original sources
arXiv2008

Associated production of prompt photons and heavy quarks in off-shell gluon-gluon fusion

In the framework of the kt-factorization approach, we study the production of prompt photons associated with heavy (charm and beauty) quarks in hadron-hadron collisions at high energies. Our consideration is based on the amplitude for the production of a single photon associated with a quark pair in the fusion of two off-shell gluons. The total and differential cross sections are presented and the conservative error analysis is performed. Two sets of unintegrated gluon distributions in the proton have been used in numerical calculation: the one obtained from Ciafaloni-Catani-Fiorani-Marchesini evolution equation and the other from Kimber-Martin-Ryskin prescription. The theoretical results are compared with recent experimental data taken by the CDF collaboration at the Fermilab Tevatron. Our analysis extends to specific angular correlations between the produced prompt photons and muons originating from semileptonic decays of the final charmed or beauty quarks. We point out the importance of such observables, which can serve as a crucial test for the unintegrated gluon densities in a proton. Finally, we extrapolate the theoretical predictions to the CERN LHC energies. This paper is dedicated to the memory of P.F. Ermolov, who died on May 14, 2008.

hep-ph↗
arXiv2008

Prompt photon hadroproduction at high energies in off-shell gluon-gluon fusion

The amplitude for production of a single photon associated with quark pair in the fusion of two off-shell gluons is calculated. The matrix element found is applied to the inclusive prompt photon hadroproduction at high energies in the framework of kt-factorization QCD approach. The total and differential cross sections are calculated in both central and forward pseudo-rapidity regions. The conservative error analisys is performed. We used the unintegrated gluon distributions in a proton which were obtained from the full CCFM evolution equation as well as from the Kimber-Martin-Ryskin prescription. Theoretical results were compared with recent experimental data taken by the D0 and CDF collaborations at Fermilab Tevatron. Theoretical predictions for the LHC energies are given.

hep-ph↗
arXiv2007

Beauty production in two-photon interactions at LEP2: kt-factorization versus data

Inclusive beauty quark production in photon-photon collisions at CERN LEP2 is considered in the framework of the kt-factorization approach. Both direct and resolved photon contributions are taken into account. The unintegrated gluon distributions in a photon are either obtained from the full CCFM evolution equation or from the Kimber-Martin-Ryskin prescription. The predicted beauty cross section reasonably agrees with the recent experimental data taken by the ALEPH collaboration. We argue that theoretical and experimental studies of the azimuthal correlations in heavy quark production at high energies can serve as a crucial probe of the unintegrated gluon densities.

hep-ph↗
arXiv2007

Upsilonium polarization as a touchstone in understanding the proton dynamics in QCD

In the framework of the k_t-factorization approach, the production of $Υmesons at the Fermilab Tevatron and CERN LHC is considered, and the predictions on the spin alignment parameter $α$ are presented. We argue that measuring the polarization of quarkonium states can serve as a crucial test discriminating two competing theoretical approaches to parton dynamics in QCD.

hep-ph↗
arXiv2007

Critical tests of unintegrated gluon distributions

We use the unintegrated Parton Density Functions of the gluon obtained from a fit to measurements of the structure functions F2 and F2c at HERA to describe the experimental data for F2b, FL and FL at fixed W.

hep-ph↗
arXiv2007

Heavy Quarks: Summary Report

The present status of the heavy-quark production theory is critically reviewed in the first contribution. The second contribution summarises the present heavy flavour data from HERA and gives an outlook of what can be expected from HERA-II. The potential of the LHC experiments for charm and beauty physics is reviewed in the 3rd contribution. Then the relevance of saturation and small-x effects to heavy quark production at HERA and at the LHC are discussed. The non-perturbative aspects of heavy-quark fragmentation and their relevance to HERA and LHC are discussed in the next contribution. Finally, a comparison of different theoretical predictions for HERA and LHC based on different approaches is presented.

hep-ph↗
arXiv2006

Prompt photon production with $k_T-$factorization

We consider the prompt photon production at modern high energy colliders in the framework of $k_T-$factorization approach. We compare our theoretical predictions with recent experimental data at HERA and Tevatron, empahasizing the distinction between our theoretical predictions and the results of NLO QCD calculations. Finally, we extrapolate our predictions to LHC energies.

hep-ph↗
arXiv2006

Charm photoproduction at HERA: kt-factorization versus experimental data

We calculate the cross section of charm photoproduction at HERA collider in the framework of the kt-factorization QCD approach. Our analysis cover the inclusive charm production as well as charm and associated jet production processes. Both photon-gluon and gluon-gluon fusion mechanisms are taken into account. The unintegrated gluon densities in a proton and in a photon obtained from the full CCFM, from unified BFKL-DGLAP evolution equations as well as from the Kimber-Martin-Ryskin prescription are used. Our theoretical results are compared with the recent experimental data taken by the H1 and ZEUS collaborations at HERA. Special attention is put on the specific angular correlations which can provide unique information about non-collinear gluon evolution dynamics.

hep-ph↗
arXiv2006

Towards precision determination of unintegrated Parton Density Functions

First attempts are described to determine the unintegrated Parton Density Function of the gluon from a fit to measurements of the structure function $F_2(x,Q^2)$ and also $F_2^c(x,Q^2)$ measured at HERA. Reasonable descriptions of both structure functions are obtained, but the gluon densities determined are different.

hep-ph↗
arXiv2006

Deep inelastic beauty production at HERA in the kt-factorization approach

We calculate the cross section of beauty production in electron-proton deep inelastic scattering at HERA collider in the framework of the kt-factorization approach. The unintegrated gluon distributions in a proton are obtained from the full CCFM, from unified BFKL-DGLAP evolution equations as well as from the Kimber-Martin-Ryskin prescription. We investigate different production rates and study the b-quark contribution to the inclusive proton structure function F2(x,Q2) at small x and at moderate and high values of Q2. Our theoretical results are compared with the recent experimental data taken by the H1 and ZEUS collaborations. We demonstrate the importance of leading ln 1/x contributions in description of the HERA data.

hep-ph↗
arXiv2006

Beauty photoproduction at HERA: kt-factorization versus experimental data

We present calculations of the beauty photoproduction at HERA collider in the framework of the kt-factorization approach. Both direct and resolved photon contributions are taken into account. The unintegrated gluon densities in a proton and in a photon are obtained from the full CCFM, from unified BFKL-DGLAP evolution equations as well as from the Kimber-Martin-Ryskin prescription. We investigate different production rates (both inclusive and associated with hadronic jets) and compare our theoretical predictions with the recent experimental data taken by the H1 and ZEUS collaborations. Special attention is put on the x_γ^{obs} variable which is sensitive to the relative contributions to the beauty production cross section.

hep-ph↗
arXiv2005

Unintegrated gluon distributions in D* and dijet associated photoproduction at HERA

We consider the photoproduction of D* mesons associated with two hadron jets at HERA collider in the framework of the kt-factorization approach. The unintegrated gluon densities in a proton are obtained from the full CCFM, from unified BFKL-DGLAP evolution equations as well as from the Kimber-Martin-Ryskin prescription. Resolved photon contributions are reproduced by the initial-state gluon radiation. We investigate different production rates and make comparison with the recent experimental data taken by the ZEUS collaboration. Special attention is put on the specific dijet correlations which can provide unique information about non-collinear gluon evolution dynamics.

hep-ph↗
arXiv2005

Higgs Production via Gluon Fusion with $K_T$ Factorization

We consider the Higgs boson production at high energy hadron colliders in the framework of the $k_T$-factorization approach. The attention is focused on the dominant gluon-gluon fusion subprocess. We show that $k_T$-factorization gives a possibility to investigate the associated Higgs boson and jets production.

hep-ph↗
arXiv2005

Prompt photon hadroproduction at high energies in the k_T-factorization approach

We consider the prompt photon production at high energy hadron colliders in the framework of k_T-factorization approach. The unintegrated quark and gluon distributions in a proton are determined using the Kimber-Martin-Ryskin prescription. The conservative error analisys is performed. We investigate both inclusive prompt photon and prompt photon and associated muon production rates. In Standard Model such events come mainly due to Compton scattering process where the final heavy (charm or bottom) quark produces a muon. The theoretical results are compared with recent experimental data taken by the D0 and CDF collaborations at Fermilab Tevatron. Our analysis also covers the azimuthal correlations between produced prompt photon and muon which can provide an important information about non-collinear parton evolution in a proton. Finally, we extrapolate the theoretical predictions to CERN LHC energies.

hep-ph↗
arXiv2005

Prompt photon photoproduction at HERA in the k_T-factorization approach

We present calculations of the prompt photon photoproduction at HERA collider in the k_T-factorization approach. Both direct and resolved contributions are taken into account. The conservative error analisys is performed. The unintegrated parton densities in a proton and in a photon are determined using the Kimber-Martin-Ryskin prescription. We investigate both inclusive and associated with jet prompt photon photoproduction rates. In particular, we study the angular correlations between produced photon and hadronic jet in the transverse momentum plane which can provide a unique information about non-collinear evolution dynamics. We compare our theoretical predictions with recent experimental data taken by the H1 and ZEUS collaborations.

hep-ph↗
arXiv2005

Higgs boson production at hadron colliders in the k_T-factorization approach

We consider the Higgs boson production at high energy hadron colliders in the framework of the k_T-factorization approach. The attention is focused on the dominant gluon-gluon fusion subprocess. We calculate the total cross section and transverse momentum distributions of the inclusive Higgs production using unintegrated gluon distributions in a proton obtained from the full CCFM evolution equation. We show that k_T-factorization gives a possibility to investigate the associated Higgs boson and jets production. We calculate the transverse momentum distributions and study the Higgs-jet and jet-jet azimuthal correlations in the Higgs + one or two jet production processes. We demonstrate the importance of the higher-order corrections within the k_T-factorization approach. These corrections should be developed and taken into account in the future applications.

hep-ph↗