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E. G. Ferreiro

Publications and source records attributed to E. G. Ferreiro.

At least 73 records · Page 4Linked to original sources
arXiv2008

Charmonium dynamics in dA and AA at RHIC and LHC

We discuss features of charmonium suppression at $\sqtr{s} = 200$ GeV within the framework of the Glauber-Gribov theory and the comovers interaction model. The latter approach has been extended by allowing for secondary charmonium production due to recombination of $c\bar{c}$ pairs in the medium, estimated from pp data at the same bombarding energy. Centrality and rapidity dependence of the nuclear modification factor for J/psi in d+Au, Cu+Cu and Au+Au collisions at RHIC are reproduced without fitting a single model parameter. A strong suppression of J/psi is predicted for LHC energies.

hep-ph↗
arXiv2008

Transverse momentum dependence of J/psi shadowing effects

We present a new approach to estimate the effect of the gluon shadowing in nucleus+nucleus collisions and its consequences on the J/psi production yield. Using kinematical information available from the measured J/psi production in proton+proton collisions at \sqrt s = 200 GeV, we build a Glauber Monte Carlo code which takes into account shadowing in two alternative ways: multiple scattering corrections or Q2 evolution of parton densities. We exploit the dependence of these different parameterizations to the J/psi transverse momentum and we give the first predictions on the resulting pT dependence of the nuclear modification factor in deuteron+gold collisions at the same energy.

hep-ph↗
arXiv2008

J/psi suppression and the nuclear absorption decrease with increasing energy

In the field theoretical Glauber-Gribov framework in the eikonal approximation, we show that, in hadron-nucleus collisions in the high-energy limit and under especific conditions, the rescattering contributions to the J/psi production cross-section vanish, leading to an A^1 dependence on the atomic number A -- except for nuclear effects in the nucleus structure function, the so-called shadowing. We show that the RHIC data on $J/ψ$ production in d-Au collisions can be described with nuclear shadowing alone (sigma_{abs} = 0). The corresponding results for Au-Au collisions are also presented and compared with available data.

hep-ph↗
arXiv2007

Charmonium dissociation and recombination at RHIC and LHC

Charmonium production at heavy-ion colliders is considered within the comovers interaction model. The formalism is extended by including possible secondary J/psi production through recombination and an estimate of recombination effects is made with no free parameters involved. The comovers interaction model also includes a comprehensive treatment of initial-state nuclear effects, which are discussed in the context of such high energies. With these tools, the model properly describes the centrality and the rapidity dependence of experimental data at RHIC energy, $\sqrt{s}$ = 200 GeV, for both Au+Au and Cu+Cu collisions. Predictions for LHC, $\sqrt{s}$ = 5.5 TeV, are presented and the assumptions and extrapolations involved are discussed.

hep-ph↗
arXiv2007

Universal behavior of baryons and mesons transverse momentum distributions in the framework of percolation of strings

In the framework of percolation of strings, the transverse momentum distributions in AA and hh collisions at all centralities and energies follow a universal behavior. The width of these distributions is related to the width of the distribution of the size of the clusters formed from the overlapping of the produced strings. The difference between the distributions for baryons and mesons originates in the fragmentation of clusters of several strings which enhance the particles with higher number of constituents. The results agree with SPS and RHIC data. The predictions for LHC show differences for baryons compared with RHIC. At LHC energies we obtain also a high pt suppression for pp high multiplicity events compared with pp minimum bias.

hep-ph↗
arXiv2007

Thermal Dileptons at LHC

We predict dilepton invariant-mass spectra for central 5.5 ATeV Pb-Pb collisions at LHC. Hadronic emission in the low-mass region is calculated using in-medium spectral functions of light vector mesons within hadronic many-body theory. In the intermediate-mass region thermal radiation from the Quark-Gluon Plasma, evaluated perturbatively with hard-thermal loop corrections, takes over. An important source over the entire mass range are decays of correlated open-charm hadrons, rendering the nuclear modification of charm and bottom spectra a critical ingredient.

hep-ph↗
arXiv2007

pi0 Fixed pT suppression and elliptic flow at LHC

Using a final state interaction model which describes the data on these two observables, at RHIC, we make predictions at the LHC -- using the same cross-section and pT-shift. The increase in the medium density between these two energies (by a factor close to three) produces an increase of the fixed pT pi0 suppression by a factor 2 at large pT and of v2 by a factor 1.5.

hep-ph↗
arXiv2007

Fluctuations and the clustering of color sources

We present our results on multiplicity and $p_T$ fluctuations at LHC energies in the framework of the clustering of color sources. In this approach, elementary color sources -strings- overlap forming clusters, so the number of effective sources is modified. We find that the fluctuations are proportional to the number of those clusters.

hep-ph↗
arXiv2007

Multiplicities and $J/ψ$ suppression at LHC energies

We present our predictions on multiplicities and $J/ψ$ suppression at LHC energies. Our results take into account shadowing effects in the initial state and final state interactions with the hot medium. We obtain 1800 charged particles at LHC and the $J/ψ$ suppression increases by a factor 5 to 6 compared to RHIC.

hep-ph↗
arXiv2006

Multiplicity, Transverse Momentum, Forward-Backward Long Range Correlations and Percolation of strings

The fluctuations due to the clustering of color sources can explain the behaviour of the scaled multiplicity variance and transverse momentum fluctuations with centrality. They also predict a nonmonotonic behaviour with centrality for the multiplictiy associated to high pT events. The clustering of color sources gives rise to an increase in the long-range correaltions with centrality as well as to a supression at high centrality with respect to superposition model predictions.

hep-ph↗
arXiv2006

Correlations at RHIC and the Clustering of Color Sources

We present our results on transverse momentum fluctuations and multiplicity fluctuations in the framework of the clustering of color sources. In this approach, elementary color sources -strings- overlap forming clusters, so the number of effective sources is modified. These clusters decay into particles with mean transverse momentum that depends on the number of elementary sources that conform each cluster and the area occupied by the cluster. We find a non-monotonic dependence of the $p_T$ and multiplicity fluctuations with the number of participants. In our approach, the physical mechanism responsible of these fluctuations is the same: the formation of clusters of strings that introduces correlations between the produced particles.

hep-ph↗
arXiv2006

Color strings, pomeron shadowing and Color Glass Condensate

I review the problem of parton saturation and its implications through three in principal different approaches, but somewhat related: saturation in a geometrical approach, QCD saturation through the Color Glass Condensate and shadowing in a Pomeron approach.

hep-ph↗
arXiv2006

Radial Flow in a Final State Interaction Model

In the framework of a final state interaction model, we show that the so-called radial flow, i.e. the almost linear increase of the inverse slope $T$ with the mass of the produced particle, is already contained in the initial condition -- with a slope $ $ (the so-called strength of the average radial transverse flow) which is larger than the measured one. While the precise value of the slope depends on the details of the model, the above result has a very general basis -- namely the increase with increasing $p_T$ of the fixed $p_T$ suppression, in the low $p_T$ region.

hep-ph↗
arXiv2006

Elliptic Flow and Fixed p_T Suppression in a Final State Interaction Model

It has been shown that a final state interaction model, used to describe J/psi suppression, can also describe the fixed p_T suppression of the pi^0 (and charged pions) yield at all values of p_T, with a final state interaction cross-section sigma close to one milibarn. We propose an extension of the model to the pion motion in the transverse plane - which introduces a dependence of the suppression on the azimuthal angle theta_R. Using the same value of sigma, we obtain values of the elliptic flow v_2 close to the experimental ones, for all values of p_T, including the soft p_T region.

hep-ph↗
arXiv2006

Elliptic Flow in a Final State Interaction Model

We propose a final state interaction model to describe the fixed $p_T$ suppression of the yield of particles at all values of $p_T$. We make an extension of the model to the motion in the transverse plane which introduces a dependence of the suppression on the azimuthal angle $θ_R$. We obtain values of the elliptic flow $v_{2}$ close to the experimental ones for all values of $p_T$.

hep-ph↗
arXiv2005

Multiplicity fluctuations in the string clustering approach

We present our results on multiplicity fluctuations in the framework of the string clustering approach. We compare our results --with and without clustering formation-- with CERN SPS NA49 data. We find a non-monotonic behaviour of these fluctuations as a function of the collision centrality, which has the same origin as the observed fluctuations of transverse momentum: the correlations between the produced particles due to the cluster formation.

hep-ph↗
arXiv2005

J/$ψ$ suppression at $\sqrt{\bf s} =$ 200 GeV in the comovers interaction model

The yield of $J/ψ$ per binary nucleon-nucleon collision in $AuAu$ and $CuCu$ collisions at $\sqrt{s} = 200$ GeV is computed in the framework of the dual parton model, supplemented with final state interaction (comovers interaction). For the latter we use the same value of the cross-section, $σ_{co} = 0.65$ mb, which describes the anomalous $J/ψ$ suppression observed at CERN-SPS energies. Several possibilities for the value of the absorptive cross-section are considered. Shadowing is introduced in both the comovers and the $J/ψ$ yields. A comparison with the results at CERN-SPS, including a prediction for $InIn$ collisions, is also presented.

hep-ph↗