QCD Color Dipole Research Articles

D-meson production in high energy pA collisions within the QCD color dipole transverse momentum representation

The D-meson production is investigated by considering the unintegrated gluon distribution within the dipole approach in the momentum representation. We analyze the D-meson spectrum accounting for the effects of nonlinear behavior of the QCD dynamics which can be accordingly addressed in the dipole framework. The unintegrated gluon distribution is obtained by using geometric scaling property and the results are compared to the Glauber–Gribov framework. The absolute transverse momentum spectra and the nuclear modification ratios are investigated. Predictions are compared with the experimental measurements by the ALICE and LHCb Collaborations in pA collisions for different rapidity bins.

Coherent photoproduction of heavy quarkonia on nuclei

The differential cross section of coherent photo-production of heavy quarkonia on nuclear targets is calculated within the QCD color dipole formalism. The higher-twist nuclear shadowing corresponding to the $\bar QQ$ Fock component of the photon, is calculated including the correlation between dipole orientation $\vec r$ and impact parameter of a collision $\vec b$, which is related to the transverse momentum transfer via Fourier transform. We also included the leading twist gluon shadowing corresponding to higher Fock components of the photon containing gluons, which have specifically short coherence time, especially for multi-gluon components, even at very high energies. The contribution of such fluctuating gluonic dipole is calculated employing the path-integral technique. Our results are in good agreement with recent ALICE data on charmonium production in ultra-peripheral nuclear collisions.

Prompt photon production in high-energy pA collisions at forward rapidity

Prompt photon production in hadronic collisions at the RHIC and the LHC energies is investigated within the QCD color dipole approach. Predictions for the nuclear modification factor in $pA$ collisions are evaluated based on parton saturation framework and the results are compared to the experimental measurements as a function of the photon transverse momentum at different rapidity bins. The reliability of the models is performed with the data from PHENIX, ATLAS, and ALICE Collaborations. Moreover, we show that the observed $x_T$-scaling of prompt photon production in $pp$ and $pA$ collisions can positively be addressed in the QCD color dipole formalism.

The color dipole picture for prompt photon production in pp and pPb collisions at the CERN-LHC

A study on the prompt photon production within the QCD color dipole picture with emphasis in pp and pA collisions at the LHC energy regimes is performed. We present predictions for the differential cross section as a function of photon transverse momentum at different rapidity bins considering updated phenomenological color dipole models, which take into account the QCD gluon saturation physics. The results are directly compared to the recent experimental measurements provided by CMS and ATLAS Collaborations, showing a reasonable agreement in all rapidity bins with no free parameters. Special attention is given to the IPSAT model given its good description of the data in all rapidity bins from low- to high-p_{T} ranges. As a result, a free-parameter approach has succeeded in describing the LHC data for prompt photon production, while new predictions for the 13-TeV data is presented in view of new data to confirm such prospect.

Soft diffraction within the QCD color dipole picture

In this work we consider the QCD parton saturation models to describe soft interactions at the high energy limit. The total and elastic cross sections as well as the elastic slope parameter are obtained for proton-proton and pion-proton collisions and compared to recent experimental results. The analyses are done within the color dipole formalism taking into account saturation models which have been tested against DIS data. The main point is that the match between soft and hard interaction occurs in the saturation region which can be described by high density QCD approaches. Discussion is performed on the main theoretical uncertainties associated with calculations.

Investigating entanglement entropy at small x in DIS off protons and nuclei

In this work we analyse the entanglement entropy in deep inelastic scattering off protons and nuclei. It is computed based on the formalism where the partonic state at small-x is maximally entangled with proton being constituted by large number of microstates occuring with equal probabilities. We consider analytical expressions for the number of gluons, N_{gluon}, obtained from gluon saturation models for the dipole-target amplitudes within the QCD color dipole picture. In particular, the nuclear entanglement entropy per nucleon is studied. We also study the underlying uncertainties on these calculations and compare the results to similar investigations in literature.

Investigating the Soft Processes within the QCD Color Dipole Picture

We consider the QCD parton saturation models to describe the soft interactions at the high-energy limit. The total and elastic cross-sections, as well as the elastic slope parameter, are obtained for proton-proton and pion-proton collisions and compared to recent experimental results.

Predictions for exclusive vector meson production in the electron-ion collider

We calculate the nuclear cross section for coherent and incoherent vector meson production within the QCD color dipole picture, including saturation effects. Predictions for scattering on both light and heavy nuclei are given over a wide range of energy. Our analysis shows that coherent process should be dominant in the future electron-ion collider.

Exclusive vector meson production in electron-ion collisions

We calculate the nuclear cross section for coherent and incoherent vector meson production within the QCD color dipole picture, including saturation effects. Theoretical estimates for scattering on both light and heavy nuclei are given over a wide range of energy.

High-energy electroweak neutrino-nucleon deeply virtual Compton scattering

In this work we estimate the differential and total cross sections for the high-energy deeply virtual Compton scattering in the weak sector. In the weak neutral sector one considers neutrino scattering off an unpolarized proton target through the exchange of ${Z}^{0}$. We numerically compute the process ${Z}^{*}p\ensuremath{\rightarrow}\ensuremath{\gamma}p$ within the QCD color dipole formalism, which successfully describes the current high-energy electromagnetic DVCS experimental data. We also discuss possible applications for the weak charged sector and perform predictions for scattering on nuclear targets.

Small-x neutrino–hadron structure functions within the QCD color dipole picture

We present an exploratory QCD analysis of the neutrino structure functions in charged current DIS using the color dipole formalism. The dipole cross sections are taken from recent phenomenological/theoretical studies in deep inelastic inclusive production. The theoretical predictions are compared to the available experimental results in the small-x region, which has never been considered so far.

Revisiting the phenomenology on the QCD color dipole picture

Using the QCD dipole picture of the hard BFKL Pomeron, we perform a 3 parameter fit analysis of the recent inclusive structure function experimental measurements at small-$x$ and intermediate $Q^2$. As a byproduct, the longitudinal structure function and the gluon distribution are predicted without further adjustments. The data description is quite reasonable, being timely a further study using resummed NLO BFKL kernels along the lines of recent theoretical developments.

The QCD pomeron in ultraperipheral heavy ion collisions: IV. Photonuclear production of vector mesons

The photonuclear production of vector mesons in ultraperipheral heavy ion collisions is investigated within the QCD color dipole picture, with particular emphasis on the saturation model. The integrated cross section and the rapidity distribution for the A + A --> V + A + A (V = rho, omega, phi, J/Psi) process are computed and theoretical estimates for scattering on both light and heavy nuclei are given for energies of RHIC and LHC. A comparison with the recent STAR data on coherent production of rho mesons is also presented. Furthermore, we calculate the photoproduction of vector mesons in proton-proton collisions at RHIC, Tevatron and LHC energies.

Nuclear exclusive vector meson photoproduction

We calculate the nuclear cross section for vector meson exclusive photoproduction within the QCD color dipole picture and in the Regge approach. For the former approach, we have considered the phenomenological saturation model, whereas for the latter we use a model based on the dipole Pomeron framework. Theoretical estimates for scattering on both light and heavy nuclei are given for a large range on energy.