Search

The exclusive dilepton photoproduction in pp and pAu collisions at RHIC is investigated considering the contribution of the Bethe–Heitler (BH) and the timelike Compton scattering (TCS) processes. The TCS amplitude is estimated at next-to-leading-order of the strong running coupling constant α s and assuming the Goloskokov–Kroll model for the quark and gluon generalized parton distributions. The TCS differential cross section is estimated as well the contribution associated to the interference between the TCS and BH amplitudes. Predictions for the TCS, BH and interference contributions are presented considering the kinematical range covered by the RHIC detectors. [ABSTRACT FROM AUTHOR]

In this paper we revisit the double vector meson production in $$\gamma \gamma $$ interactions at heavy ion collisions and present, by the first time, predictions for the $$\rho \rho $$ and $$J/\Psi J/\Psi $$ production in proton-nucleus and proton-proton collisions. In order to obtain realistic predictions for rapidity distributions and total cross sections for the double vector production in ultra peripheral hadronic collisions we take into account the description of $$\gamma \gamma \rightarrow VV$$ cross section at low energies as well as its behavior at large energies, associated to the gluonic interaction between the color dipoles. Our results demonstrate that the double $$\rho $$ production is dominated by the low energy behavior of the $$\gamma \gamma \rightarrow VV$$ cross section. In contrast, for the double $$J/\Psi $$ production, the contribution associated to the description of the QCD dynamics at high energies contributes significantly, mainly in pp collisions. Predictions for the RHIC, LHC, FCC, and CEPC-SPPC energies are shown. [ABSTRACT FROM AUTHOR]

At very high energies we expect that the hadronic cross sections satisfy the Froissart bound, which is a well-established property of the strong interactions. In this energy regime we also expect the formation of the Color Glass Condensate, characterized by gluon saturation and a typical momentum scale: the saturation scale Qs. In this paper we show that if a saturation window exists between the nonperturbative and perturbative regimes of Quantum Chromodynamics (QCD), the total cross sections satisfy the Froissart bound. Furthermore, we show that our approach allows us to describe the high energy experimental data on $pp/p\bar p$ total cross sections. [ABSTRACT FROM AUTHOR]

Perturbative Quantum Chromodynamics (pQCD) predicts that the small-x gluons in the hadron wavefunction should form a Color Glass Condensate (CGC), which has universal properties, which are the same for nucleon or nuclei. Making use of the results in V.P. Goncalves, M.S. Kugeratski, M.V.T. Machado, F.S. Navarra, Phys. Lett. B643, 273 (2006), we study the behavior of the anomalous dimension in the saturation models as a function of the photon virtuality and of the scaling variable rQs, since the main difference among the known parameterizations are characterized by this quantity. [ABSTRACT FROM AUTHOR]

We propose a simple model for the total pp/pp̄ cross-section, which is a generalization of the minijet model with the inclusion of a window in the pT-spectrum associated to the saturation physics. Our model implies a natural cutoff for the perturbative calculations which modifies the energy behavior of this component, so that it satisfies the Froissart bound. Including the saturated component, we obtain a satisfactory description of the very high energy experimental data. [ABSTRACT FROM AUTHOR]

In this contribution we consider the influence of nonlinear gluon evolution in the production of prompt photons at the LHC pp collider. We consider the EHKQS parton distributions, which are based on the GLR-MQ evolution equations, and imply in an enhanced small-x gluon distribution at Q2 ≤ 10 GeV2 relative to the LO DGLAP gluon distribution. We find an enhancement of low-pT photons for both single and double photon production. Consequences of this effect for the Quark-Gluon Plasma searches and for the QCD background to Higgs are also discussed. [ABSTRACT FROM AUTHOR]

The discovery of the jet quenching in central Au+Au collisions at the Relativistic Heavy-Ion Collider (RHIC) at Brookhaven National Laboratory has provided clear evidence for the formation of strongly interacting dense matter. It has been predicted to occur due to the energy loss of high energy partons that propagate through the quark–gluon plasma. In this paper we investigate the dependence of the parton energy loss due to elastic scatterings in a parton plasma on the value of the strong coupling and its running with the evolution of the system. We analyze different prescriptions for the QCD coupling and calculate the energy and length dependence of the fractional energy loss. Moreover, the partonic quenching factor for light and heavy quarks is estimated. We found that the predicted enhancement of the heavy to light hadrons (D/π) ratio is strongly dependent on the running of the QCD coupling constant. [ABSTRACT FROM AUTHOR]

The longitudinal structure function in deep-inelastic scattering is one of the observables from which the gluon distribution can be unfolded. Consequently, this observable can be used to constrain the QCD dynamics at smallx. In this work we compare the predictions of distinct QCD models with the recent experimental results forFL(x,Q2) at smallxand lowQ2 obtained by the H1 Collaboration. We focus mainly on the color dipole approach, selecting those models which include saturation effects. Such models are suitable at this kinematical region and also resum a wide class of higher-twist contributions to the observables. Therefore, we investigate the influence of these corrections toFL in the present region of interest. [ABSTRACT FROM AUTHOR]

The longitudinal structure function in deep-inelastic scattering is one of the observables from which the gluon distribution can be unfolded. Consequently, this observable can be used to constrain the QCD dynamics at smallx. In this work we compare the predictions of distinct QCD models with the recent experimental results forFL(x,Q2) at smallxand lowQ2 obtained by the H1 Collaboration. We focus mainly on the color dipole approach, selecting those models which include saturation effects. Such models are suitable at this kinematical region and also resum a wide class of higher-twist contributions to the observables. Therefore, we investigate the influence of these corrections toFL in the present region of interest. [ABSTRACT FROM AUTHOR]