945 research outputs found
The Charm of the Proton and the Production
We propose a two component model for charmed baryon production in
collisions consisting of the conventional parton fusion mechanism and
fragmentation plus quarks recombination in which a valence diquark from
the proton recombines with a -sea quark to produce a . Our
two-component model is compared with the intrinsic charm two-component model
and experimental data.Comment: 6 pages, LaTex, 2 figures included, aipproc.sty included. Talk
presented at Simposio Latino Americano de Fisica de Altas Energias, Merida,
Mexico, November 199
The Polarization and the Recombination Mechanism
We use the recombination and the Thomas Precession Model to obtain a
prediction for the polarization in the
reaction. We study the effect of the recombination function on the
polarization.Comment: 4 pages, LaTex, 1 figures included, aipproc.sty included. Talk
presented at Simposio Latino Americano de Fisica de Altas Energias, Merida,
Mexico, November 199
On the intrinsic charm and the recombination mechanisms in charm hadron production
We study production in and interactions. Recent
experimental data from the SELEX and E791 Collaborations at FNAL provide
important information on the production mechanism of charm hadrons. In
particular, the production of the baryon provides a good test of
the intrinsic charm and the recombination mechanisms, which have been proposed
to explain the so called leading particle effects.Comment: 11 pages, two figures (postscript), late
Three and two-hadron correlations in \sqrt{s_{NN}}=200 GeV proton-proton and nucleus-nucleus collisions
We compare the azimuthal correlations arising from three and two hadron
production in high energy proton-proton and nucleus-nucleus collisions at
\sqrt{s_{NN}}=200 GeV, using the leading order matrix elements for two-to-three
and two-to-two parton-processes in perturbative QCD. We first compute the two
and three hadron production cross sections in mid-rapidity proton-proton
collisions. Then we consider Au + Au collisions including parton energy loss
using the modified fragmentation function approach. By examining the
geometrical paths the hard partons follow through the medium, we show that the
two away-side partons produced in two-to-three processes have in average a
smaller and a greater path length than the average path length of the away-side
parton in two-to-two processes. Therefore there is a large probability that in
the former processes one of the particles escapes while the other gets
absorbed. This effect leads to an enhancement in the azimuthal correlations of
the two-to-three with respect to the two-to-two parton-processes when comparing
to the same processes in proton-proton collisions since in average the particle
with the shortest path length looses less energy with respect to the away side
particle in two-to-two processes. We argue that this phenomenon may be
responsible for the shape of the away-side in azimuthal correlations observed
in mid-rapidity Au + Au collisions at RHIC.Comment: 4 pages, 2 figure
The broad away side of azimuthal correlations: 3 vs 2 final state particles in high energy nuclear collisions
In high energy heavy ion collisions at RHIC there are important aspects of
the medium induced dynamics, that are still not well understood. In particular,
there is a broadening and even a double hump structure of the away-side peak
appearing in azimuthal correlation studies in Au+Au collisions which is absent
in p+p collisions at the same energies. These features are already present but
suppressed in p+p collisions: 2 to 3 parton processes produce such structures
but are suppressed with respect to 2 to 2 processes. We argue that in A+A
collisions the different geometry for the trajectories of 3 as opposed to 2
particles in the final state, together with the medium induced energy loss
effects on the different cross sections, create a scenario that enhances
processes with 3 particles in the final state, which gives on average this
double hump structure.Comment: Prepared for the 5th International Workshop on High-pT Physics at
LHC, ICN-UNAM, 27 Sep.-1 Oct, 201
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