478 research outputs found
Evolution of particle density in high-energy pp collisions
We study the evolution of the particle density, dn/d\eta at fixed \eta with
the beam rapidity Y in the framework of string percolation model. Our main
results are: (i) The width of the "plateau" increases proportionally to Y, (ii)
limiting fragmentation is violated, and (iii) the particle density, reduces to
a step function.Comment: 8 pages, 2 figures, to appear in Nuclear Physics A. Minor changes are
don
Absorption and J/psi Suppression in Heavy Ion Collisions
We discuss the J/psi suppression in the framework of multiple collision
models. From the analysis of the Pb-Pb NA50 data we conclude that the strength
of the absorption has increased, but we find no clear evidence for the
formation of the quark-gluon plasma.Comment: 8 pages, 4 figure
Energy conservation and scaling violations in particle production
We use a simple Colour Glass Condensate/String Percolation Model argument to
show the existence, due to energy conservation, of bounds to the violation of
Feynman scaling and limiting fragmentation.Comment: 5 pages, 1 figure. Final versio
Density saturation and the decrease of the normalised width of the multiplicity distribution in high energy pp collisions
It is experimentally observed that the width of the KNO multiplicity
distribution --or the negative binomial parameter 1/k-- for pp collisions, in
the energy region 10 to 1800 GeV, is an increasing function of the energy. We
argue that in models with parton or string saturation such trend will necessary
change: at some energy the distribution will start to become narrower. In the
framework of percolating strings, we have estimated the change to occur at an
energy of the order of 5--10 TeV.Comment: 10 pages, 4 figures, uses elsart and amsmath; comparison with some
other models was added; version accepted by PL
Cumulative particle production as a rare event
The generalization of the Glauber formula for cumulative production events is
derived. On its basis the multiplicity distribution in such events is related
to the one in the minimum bias events. As compared to the rare events of type
, the formula involves a shift in the arguments determined by the
multiplicity from a collision with a cluster of several nucleons.Comment: 11 pages, LaTe
Percolation approach to phase transitions in high energy nuclear collisions
We study continuum percolation in nuclear collisions for the realistic case
in which the nuclear matter distribution is not uniform over the collision
volume, and show that the percolation threshold is increased compared to the
standard, uniform situation. In terms of quark-gluon plasma formation this
means that the phase transition threshold is pushed to higher energies.Comment: 7 pages, 4 figures (PS), LaTeX2e using fontenc, amsmath, epsfi
Particle rapidity density and collective phenomena in heavy ion collisions
We analyse recent results on charged particle pseudo-rapidity densities from
RHIC in the framework of the Dual String Model, in particular when including
string fusion. The model, in a simple way, agrees with all the existing data
and is consistent with the presence of the percolation transition to the
Quark-Gluon Plasma already at the CERN-SPS. It leads to strict saturation of
the particle (pseudo-)rapidity density, normalised to the number of participant
nucleons, as that number increases. A comparison with recent WA98 data is
presented.Comment: 6 pages, 3 ps figures, Latex2e with amsmath. To appear in the
Proceedings of the XXX International Symposium on Multiparticle Dynamics
(Lake Balaton, October 2000
The black disk and the dip in the differential elastic cross section at asymptotic energy
We test the validity of the black disk limit in elastic scattering by
studying the evolution of the dip in the scaling variable
, where is the transverse momentum squared at
the dip and the total cross section. As
and , may consistently be approaching the black
disc value,
GeV mb.Comment: 6 pages, 2 figure
Long range correlations, event simulation and parton percolation
We study the RHIC data on long range rapidity correlations, comparing their
main trends with different string model simulations. Particular attention is
paid to color percolation model and its similarities with color glass
condensate. As both approaches corresponds, at high density, to a similar
physical picture, both of them give rise to a similar behavior on the energy
and the centrality of the main observables. Color percolation explains the
transition from low density to high density.Comment: Contribution to the meeting : Saturation, the CGC and the Glasma BNL.
May 10-12, accepted in Nuclear Physics
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