505 research outputs found
Melting the Color Glass Condensate at the LHC
The charged particle multiplicity in central AA collisions and the production
of heavy flavors in pA collisions at the LHC is predicted in the CGC framework.Comment: Presented at the Workshop on Heavy Ion Collisions at the LHC: Last
Call for Predictions, Geneva, Switzerland, 14 May - 8 Jun 2007; 2 pages, 3
figure
Low-cost fermions in classical field simulations
We discuss the possible extension of the bosonic classical field theory
simulations to include fermions. This problem has been addressed in terms of
the inhomogeneous mean field approximation by Aarts and Smit. By performing a
stochastic integration of an equivalent set of equations we can extend the
original 1+1 dimensional calculations so that they become feasible in higher
dimensions. We test the scheme in 2 + 1 dimensions and discuss some classical
applications with fermions for the first time, such as the decay of oscillons.Comment: 13 pages, revtex
Ekpyrosis and inflationary dynamics in heavy ion collisions: the role of quantum fluctuations
We summarize recent significant progress in the development of a
first-principles formalism to describe the formation and evolution of matter in
very high energy heavy ion collisions. The key role of quantum fluctuations
both before and after a collision is emphasized. Systematic computations are
now feasible to address early time dynamics essential to quantifying properties
of strongly interacting quark-gluon matter.Comment: Talk by R.V. at Quark Matter 2011, Annecy, France, May 23-28, 2011.
LaTex, 4 pages; v2, final version to appear in J. Phys.
Gluon propagation inside a high-energy nucleus
We show that, in the light-cone gauge, it is possible to derive in a very
simple way the solution of the classical Yang-Mills equations for the collision
between a nucleus and a proton. One important step of the calculation is the
derivation of a formula that describes the propagation of a gluon in the
background color field of the nucleus. This allows us to calculate observables
in pA collisions in a more straightforward fashion than already proposed. We
discuss also the comparison between light-cone gauge and covariant gauge in
view of further investigations involving higher order corrections.Comment: 12 pages, 2 figure
Heavy flavor production in pA collisions
Heavy quark production in high-energy proton-nucleus (pA) collisions is
described in the framework of the Color Glass Condensate. kT factorization is
broken even at leading order albeit a more general factorization in pA holds at
this order in terms of 2, 3 and 4 point correlators of Wilson lines in the
nuclear target. The x-evolution of these correlators is computed in the large A
and large N mean field limit of the Balitsky-Kovchegov equation. We show
results for heavy quark production at RHIC and LHC energies.Comment: Talk given at QM2006. 4
Wilson line correlator in the MV model: relating the glasma to deep inelastic scattering
In the color glass condensate framework the saturation scale measured in deep
inelastic scattering of high energy hadrons and nuclei can be determined from
the correlator of Wilson lines in the hadron wavefunction. These same Wilson
lines give the initial condition of the classical field computation of the
initial gluon multiplicity and energy density in a heavy ion collision. In this
paper the Wilson line correlator in both adjoint and fundamental
representations is computed using exactly the same numerical procedure that has
been used to calculate gluon production in a heavy ion collision. In particular
the discretization of the longitudinal coordinate has a large numerical effect
on the relation between the color charge density parameter g^2 mu and the
saturation scale Qs. Our result for this relation is Qs = 0.6 g^2 mu, which
results in the classical Yang-Mills value for the "gluon liberation
coefficient" c = 1.1.Comment: 8 pages, 10 figures, RevTEX4, V2: typo corrections, V3: small
clarifications, to be published in EPJ
Drell-Yan production and Lam-Tung relation in the Color Glass Condensate formalism
We study the Drell-Yan production cross section and structure functions in
proton (deuteron)-nucleus collisions using the Color Glass Condensate
formalism. The nucleus is treated in the Color Glass Condensate framework which
includes both higher twist effects due to the inclusion of multiple scatterings
and leading twist pQCD shadowing due to the small x resummation, while the
proton (or deuteron) is treated within the DGLAP improved parton model. In
particular, the Drell-Yan structure functions are used in order to investigate
the Lam-Tung relation at small x, which is known to be identically zero at
leading twist up to Next-to-Leading order, and is thus a good playground for
studying higher twist effects. In agreement with this, we find that violations
of this relation are more important for low momentum and invariant mass of the
Drell-Yan pair, and also in the region of rapidity that corresponds to smaller
values of x in the nucleus.Comment: 25 pages, 16 postscript figure
FIRST DESCRIPTION OF THE NEST AND NESTLING OF WHITE-BANDED TYRANNULET Mecocerculus stictopterus (TYRANNIDAE)
We provide the first descriptions of the nest and nestlings of White-banded Tyrannulet Mecocerculus stictopterus, only the second nest description for this genus of small Andean flycatchers (Tyrannidae). We found a single nest with newly hatched nestlings in early November, near Papallacta, northeastern Ecuador. The nest was an open cup composed of lichens and mosses, bound together with spider webs and saddled over a small branch. The natal down of the nestlings was bicolored, creating a camouflaging, sun-dappled effect.Proporcionamos las primeras descripciones del nido y pichones del Tiranillo Alibandeado Mecocerculus stictopterus, apenas la segunda descripciĂłn de un nido de este gĂ©nero de pequeños atrapamoscas andinos (Tyrannidae). A principios de noviembre, cerca de Papallacta, noreste de Ecuador, encontramos un nido con pichones reciĂ©n eclosionados. El nido era una copa abierta compuesta de lĂquenes y musgos, unida con telarañas y ensillada sobre una pequeña rama. El plumĂłn natal de los pichones era bicolor, moteado, con un efecto camuflado de manchas de luz y sombra
Non-perturbative computation of double inclusive gluon production in the Glasma
The near-side ridge observed in A+A collisions at RHIC has been described as
arising from the radial flow of Glasma flux tubes formed at very early times in
the collisions. We investigate the viability of this scenario by performing a
non-perturbative numerical computation of double inclusive gluon production in
the Glasma. Our results support the conjecture that the range of transverse
color screening of correlations determining the size of the flux tubes is a
semi-hard scale, albeit with non-trivial structure. We discuss our results in
the context of ridge correlations in the RHIC heavy ion experiments.Comment: 25 pages, 11 figures, uses JHEP3.cls V2: small clarifications,
published in JHE
Dilepton production from the Color Glass Condensate
We consider dilepton production in high energy proton-nucleus (and very
forward nucleus-nucleus) collisions. Treating the target nucleus as a Color
Glass Condensate and describing the projectile proton (nucleus) as a collection
of quarks and gluons as in the parton model, we calculate the differential
cross section for dilepton production in quark-nucleus scattering and show that
it is very sensitive to the saturation scale characterizing the target nucleus.Comment: 9 pages LaTeX document, 1 postscript figur
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