Heavy Quark Photoproduction Research Articles

Exclusive heavy quark photoproduction in pp, pPb and PbPb collisions at the LHC and FCC energies

In this paper we present a comprehensive analysis of the exclusive heavy quark photoproduction in pp, pPb and PbPb collisions at LHC and FCC energies using the color dipole formalism and taking into account of nonlinear corrections to the QCD dynamics. We estimate the rapidity distributions and cross sections for the charm and bottom production considering three phenomenological models for the dipole-proton scattering amplitude that are able to describe the ep HERA data. Our results indicate that a future experimental analysis of this process is feasible, which will allow us to improve our understanding of the QCD dynamics.

Inclusive heavy quark photoproduction in pp, pPb and PbPb collisions at Run 2 LHC energies

In this paper we present a comprehensive analysis of the inclusive heavy quark photoproduction in pp, pPb and PbPb collisions at Run 2 LHC energies using the Color Dipole formalism. The rapidity distributions and total cross sections for the charm and bottom production are estimated considering the more recent phenomenological models for the dipole-proton scattering amplitude, which are based on the Color Glass Condensate formalism and are able to describe the inclusive and exclusive ep HERA data. Moreover, we present, by the first time, the predictions for the transverse momentum distributions of the D and B mesons produced in the photon-induced interactions.

Nuclear effects in photoproduction of heavy quarks and vector mesons in ultraperipheral PbPb andpPb collisions at energies available at the CERN Large Hadron Collider

The comparison of photoproduction cross sections for $c\bar{c}$ and b-b(bar) in PbPb and pPb collisions can give sensitivity to nuclear shadowing effects. The photoproduction of vector mesons is even more sensitive to the underlying gluon distributions. In this study we present the cross sections and rapidity dependence of the photoproduction of heavy quarks and exclusive production of vector mesons in ultraperipheral pPb and PbPb collisions at the Large Hadron Collider at sqrt(s_NN)=5 TeV and sqrt(s_NN)=2.76$ TeV, respectively. The potentials of using these processes for constraining nuclear gluon shadowing are explored. It is found that photoproduction of $J/\psi$ and $\Upsilon$ in PbPb collisions in particular exhibit very good sensitivity to gluon shadowing.

Constraining gluon shadowing using photoproduction in ultraperipheralpAandAAcollisions

Photoproduction of heavy quarks and exclusive production of vector mesons in ultraperipheral proton-nucleus and nucleus-nucleus collisions depend significantly on nuclear gluon distributions. In the present study we investigate quantitatively the extent of the applicability of these processes at the Large Hadron Collider (LHC) in constraining the shadowing component of nuclear gluon modifications.

Gluon distributions in nuclei probed at energies available at the CERN Large Hadron Collider

Using updated gluon distributions from global fits to data, we investigate the sensitivity of direct photoproduction of heavy quarks and exclusive production of vector mesons to varying strength of gluon modifications. Implications of using these processes for constraining nuclear gluon distributions are discussed.

Heavy quark photoproduction in pp coherent interactions at LHC

In this work we analyse the possibility of constraining the QCD dynamics at high energies studying the heavy quark photoproduction at LHC in coherent interactions. The rapidity distribution and total cross section for charm and bottom production are estimated using three different phenomenological saturation models which successfully describe the HERA data. Our results indicate that the experimental study of the inclusive heavy quark photoproduction can be very useful to discriminate between the classical and quantum versions of the Color Glass Condensate (CGC) formalism.

Heavy quark photoproduction in coherent interactions at high energies

We calculate the inclusive and diffractive photoproduction of heavy quarks in proton-proton collision at Tevatron and CERN LHC energies, where the photon reaches energies larger than those ones accessible at DESY-HERA. The integrated cross section and the rapidity distributions for charm and bottom production are computed within the color dipole picture employing three phenomenological saturation models based on the color glass condensate formalism. Our results demonstrate that the experimental analyses of these reactions are feasible and that the cross sections are sensitive to the underlying parton dynamics.

Photon-hadron interactions in pA/AA collisions and the QCD dynamics

In this contribution we study the photoproduction of heavy quarks in coherent proton-nucleus (pA) and nucleus-nucleus (AA) interactions for RHIC and LHC energies and analyze if this process can be used to determine the QCD dynamics at high energies. The integrated cross section and rapidity distribution are estimated. Our results indicate that the nonlinear dynamics can be proven in those reactions, which are well suited for studing saturation effects.

Diffractive photoproduction of heavy quarks in hadronic collisions

In this article we study the diffractive photoproduction of heavy quarks in hadronic ($pp/pA/AA$) interactions for Tevatron and LHC energies. The integrated cross section and rapidity distribution for the process ${h}_{1}{h}_{2}\ensuremath{\rightarrow}{h}_{1}{h}_{2}Q\overline{Q}$ (${h}_{i}=p$, $A$ and $Q=c$, $b$) are estimated using the color glass condensate (CGC) formalism. Our results indicate that this production channel has larger cross sections than the competing reactions of double diffractive production and coherent $AA$ reactions initiated by two-photon collisions.

Coherent photon-hadron interactions inpAcollisions: Small-xphysics after HERA

In this letter we study the photoproduction of heavy quarks and vector mesons in the coherent proton-nucleus (pA) interactions for RHIC and LHC energies and analyze if these processes can be used to determine the QCD dynamics at high energies. The integrated cross section and rapidity distribution are estimated using the Color Glass Condensate (CGC) formalism. A comparison with the linear dynamics predictions is also presented. Our results indicate that the nonlinear dynamics can be proven in those reactions, which are well suited for studing saturation effects.

Two-loop QCD corrections to the vector form factors for the heavy-quark photo-production

We review on the calculation of the heavy-quark photo-production vector form factors, with the full dependence on the mass of the heavy-quark. The Feynman diagrams are evaluated within the dimensional regularization scheme and expressed in Laurent series of ɛ = (4 - D)/2, where D is the space-time dimension. The coefficients of the expansion are expressed in terms of harmonic polylogarithms. The numerical evaluation of the analytical formulas and t he threshold limit of our results are presented.

Heavy quark photoproduction in proton-proton collisions

We calculate the photoproduction of heavy quarks in proton-proton collisions at RHIC, Tevatron, and CERN LHC energies, where the photon reaches energies larger than those accessible at DESY-HERA. The integrated cross section and the rapidity distributions for open charm and bottom production are computed employing sound high energy QCD formalisms. For the linear perturbative QCD approaches we consider both the usual collinear factorization and the ${k}_{\ensuremath{\perp}}$-factorization formalisms, whereas for the nonlinear QCD (saturation) calculations one considers the Golec-Biernat-W\"usthoff and the Iancu-Itakura-Munier parametrizations for the dipole cross section within the color dipole picture.

Nuclear heavy quark photoproduction in a saturation model

We calculate the nuclear inclusive and diffractive cross sections for heavy quark photoproduction within a phenomenological saturation approach. The nuclear cross section is obtained by the extension of the saturation model through Glauber-Gribov formalism. We predict large nuclear heavy quark cross section at LHC energies.

Heavy quark photoproduction in thek⊥-factorization approach

We investigate heavy quark photoproduction based on the ${\mathit{k}}_{\ensuremath{\perp}}$-factorization approach, focusing on the results from the saturation model. The deviations between the results using the unintegrated gluon distribution considering the saturation model and the derivative of the collinear gluon distribution are analyzed. Total cross sections and ${p}_{T}$ distributions are analyzed in detail, giving the deviations between the results of the color dipole approximation and the complete semihard approach.

Peripheral heavy ion collisions as a probe of the nuclear gluon distribution

At high energies a quark-gluon plasma is expected to be formed in heavy ion collisions at RHIC and LHC. The theoretical description of these processes is directly associated to a complete knowledge of the details of medium effects in the nuclear gluon distribution. In this paper we analyze the possibility to constraint the behavior of this distribution considering peripheral heavy ion collisions. We reanalyze the photoproduction of heavy quarks for the deduction of the in-medium gluon distribution using three current parameterizations for this parton distribution. Moreover, we show that the elastic photoproduction of vector mesons is a potential process to probe the nuclear gluon distribution.

Perturbative stability of the QCD predictions for single spin asymmetry in heavy quark photoproduction

We present the threshold resummation for the single spin asymmetry in heavy flavor production by linearly polarized photons. We analyze the soft-gluon contributions to the asymmetry at fixed order in α s to the next-to-leading logarithmic accuracy. Our analysis shows that, contrary to the production cross section, the azimuthal asymmetry is practically insensitive to soft radiation. Our calculations of the asymmetry up to the 6th order in α s lead only to small corrections (of order of few percent) to the Born predictions at energies of the fixed target experiments. Fast convergence of the perturbative series for the azimuthal asymmetry is due to the factorization properties of the photon–hadron cross section. We conclude that measurements of the single spin asymmetry would provide an excellent test of pQCD applicability to heavy flavor production.

Next-to-leading order corrections to heavy flavor production in longitudinally polarized photon-nucleon collisions

A complete next-to-leading order calculation of longitudinally polarized heavy quark photoproduction is presented. All results of the purturbative calculation are given in detail. For reactions and energies of interest cross sections differential in the transverse momentum and rapidity of the heavy quark, total cross sections and the corresponding asymmetries are given. Errors in the asymmetries are estimated and the possibility to distinguish between various scerarios of the polarized gluon distribution is discussed. Our results are compared with other related publications.

HEAVY QUARK PHOTOPRODUCTION IN THE SEMIHARD QCD APPROACH AND THE UNINTEGRATED GLUON DISTRIBUTION

Processes of heavy quark photoproduction at HERA energies are considered using the semihard (k⊥ factorization) QCD approach with emphasis of the BFKL dynamics of gluon distributions. We investigate the dependences of the total cross-section of heavy quark photoproduction and also the pT distribution on different forms of the unintegrated gluon distribution. We present a comparison of the theoretical results with available H1 and ZEUS experimental data for charm and beauty photoproductions.

Polarized photoproduction of heavy quarks in next-to-leading order

The results of a next-to-leading order calculation of heavy quark production in longitudinally polarized photon-nucleon collisions are presented. At c.m. energy S =10 GeV, for γ+ p→c+X , cross sections differential in the transverse momentum and rapidity of the charmed quark c and the corresponding asymmetries are presented; also, as functions of S , integrated cross sections, K-factors and the corresponding asymmetries are given. Errors in the asymmetries are estimated and the possibility to distinguish between three scenarios differing essentially in the polarized gluon distribution is discussed.

Polarized heavy quark photoproduction in next to leading order

Results of our next-to-leading order analytic calculation for longitudinally polarized photoproduction of heavy quarks are presented. Certain differential cross sections and the corresponding asymmetries are computed for energy ranges accessible to CERN and HERA. We argue that determination of the polarized gluon distribution is possible at both places: at HERA certain acceptance cuts are necessary.