1,248 research outputs found
On the long-range correlations in hadron-nucleus collisions
Long-range correlations between multiplicities in different rapidity windows
in hadron-nucleus collisions are analyzed. After recalling the standard results
in the probabilistic model, we study them in the framework of perturbative QCD.
Considering interacting BFKL pomerons in the form of fan diagrams coupled to a
dilute projectile, analytic estimates are done for very large rapidities. The
correlation strength results weakly depending on energy and centrality or
nuclear size, and generically greater than unity. Finally, we turn to the Color
Glass Condensate framework. For a saturated projectile and considering the most
feasible experimental situation of forward and backward rapidity windows
symmetric around the center-of-mass, the resulting correlation strength turns
out to be larger than unity and shows a non-monotonic behavior with increasing
energy, first increasing and then decreasing to a limiting value. Its behavior
with increasing centrality or nuclear size depends on the considered rapidity
windows.Comment: 17 pages, LaTeX, 6 eps figures included using graphicx; v2: error in
the CGC formula corrected, conclusions of the corresponding section changed
accordingl
Medium-induced multi-photon radiation
We study the spectrum of multi-photon radiation off a fast quark in medium in
the BDMPS/ASW approach. We reproduce the medium-induced one-photon radiation
spectrum in dipole approximation, and go on to calculate the two-photon
radiation in the Moli\`{e}re limit. We find that in this limit the LPM effect
holds for medium-induced two-photon ladder emission.Comment: 5 pages, 1 figure. Proceedings of Hot Quarks 2010, La Londe Les
Maures, Franc
Nuclear Shadowing and Diffraction
The relation between diffraction in lepton-proton collisions and shadowing of
nuclear structure functions which arises from Gribov inelastic shadowing, is
described. A model realizing such relation, which produces a parameter-free
description of experimental data on nuclear structure functions at small ,
is presented. The application to the description of multiplicities in nuclear
collisions is discussed and related to other approaches.Comment: LaTeX, 6 pages, 5 eps figures, uses enclosed ws-ijmpa.cls; invited
talk given by N. Armesto at the Eighth Workshop on Non-Perturbative Quantum
Chromodynamics, Paris, France, June 7th-11th 200
AAMQS: a non-linear QCD description of new HERA data at small-x
We present a global analysis of available data on inclusive structure
functions measured in electron-proton scattering at small values of Bjorken-x,
including the latest data from the combined HERA analysis on reduced cross
sections. Our approach relies on the dipole formulation of DIS together with
the use of the non-linear running coupling BK equation for the description of
the small-x dynamics. With the resulting parametrization we are able to
describe the latest FL data measured by the H1 collaboration. Further, we
discuss the kinematical domain where significant deviations from NLO-DGLAP
should be expected and the ability of non-linnear physics to account for such
deviations.Comment: 4 pages, 2 figures, Proceedings of Quark Matter 2011, Annecy, Franc
Nuclear size and rapidity dependence of the saturation scale from QCD evolution and experimental data
The solutions of the Balitsky-Kovchegov evolution equations are studied
numerically and compared with known analytical estimations. The rapidity and
nuclear size dependences of the saturation scale are obtained for the cases of
fixed and running coupling constant. These same dependences are studied in
experimental data, on lepton-nucleus, deuteron-nucleus and nucleus-nucleus
collisions, through geometric scaling and compared with the theoretical
calculations.Comment: 8 pages, 8 figures. Contribution based on talks given by J. G.
Milhano and C. A. Salgado to the proceedings of ``Hard Probes 2004'',
Ericeira (Portugal), November 4-10, 200
A predictive phenomenological tool at small Bjorken-x
We present the results from global fits of inclusive DIS experimental data
using the Balitsky-Kovchegov equation with running coupling.Comment: 5 pages, 2 figures, prepared for the Proceedings of 'Hot Quarks 2010
Charm quenching in heavy-ion collisions at the LHC
D-meson suppression in Pb-Pb collisions at the LHC due to charm quark
in-medium energy loss is estimated within a model that describes the available
quenching measurements at RHIC. The result is compared to that previously
published by the author. The expected sensitivity of the ALICE experiment for
studying charm energy loss via fully-reconstructed D^0-meson decays is also
presented.Comment: 8 pages, 3 figures. To appear in the proceedings of Hot Quarks 2004:
Workshop for Young Scientists on the Physics of Ultrarelativistic
Nucleus-Nucleus Collisions, Taos Valley, New Mexico, 18-24 July 2004.
Submitted to J. Phys.
Energy Dependence of the Cronin Effect from Non-Linear QCD Evolution
The non-linear evolution of dense partonic systems has been suggested as one
of the novel physics mechanisms relevant to the dynamics of hadron-nucleus and
nucleus-nucleus collisions at collider energies. Here we study to what extent
the description of Cronin enhancement in the framework of this non-linear
evolution is consistent with the recent observation in 200 AGeV d--Au
collisions at the Relativistic Heavy Ion Collider. We solve the
Balitsky-Kovchegov evolution equation numerically for several initial
conditions encoding Cronin enhancement. We find that the properly normalized
nuclear gluon distribution is suppressed at all momenta relative to that of a
single nucleon. Calculating the resulting spectrum of produced gluons in p-A
and A-A collisions, we establish that the nonlinear QCD evolution is unable to
generate a Cronin type enhancement, and that it quickly erases any such
enhancement which may be present at lower energies.Comment: 4 pages, Latex, 3 eps-figure
First correction to JIMWLK evolution from the classical equations of motion
We calculate some corrections to the JIMWLK kernel in
the framework of the light-cone wave function approach to the high energy limit
of QCD. The contributions that we consider originate from higher order
corrections in the strong coupling and in the density of the projectile to the
solution of the classical Yang-Mills equations of motion that determine the
Weizs\"acker-Williams fields of the projectile. We study the structure of these
corrections in the dipole limit, showing that they are subleading in the limit
of large number of colours , and that they cannot be fully recast in the
form of dipole degrees of freedom.Comment: 4 pages, LaTeX, 2 eps figures included using graphicx, uses enclosed
iopart.cls; contribution to the proceedings of Quark Matter 2006 (Shanghai,
November 14th-20th 2006
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