4,438 research outputs found
Comparison of Nuclear Suppression Effects on Meson Production at High p_T and p_L
The medium effect on the pion distribution at high in collisions
is compared to that of the pion distribution at high in collisions.
Both the suppression of the spectra and the energy losses of the measured pions
are studied. Although the medium effect on is larger than on , the
difference is found surprisingly to be not as big as one would naively expect.Comment: 8 RevTex pages with 5 figure
Quark-hadron phase transition with surface fluctuation
The effect of surface fluctuation on the observables of quark-hadron phase
transition is studied. The Ginzburg-Landau formalism is extended by the
inclusion of an extra term in the free energy that depends on the vertical
displacements from a flat surface. The probability that a bin has a particular
net displacement is determined by lattice simulation, where the physics input
is color confinement. The surface fluctuation from bin to bin is related to
multiplicity fluctuation, which in turn is measured by the factorial moments.
It is found that both the F-scaling behavior and the scaling exponent are
essentially unaffected by the inclusion of surface fluctuation.Comment: 9 pages, LaTex, 7 figures in a single postscript file, submitted to
Phys. Rev.
Parton Distributions in the Valon Model
The parton distribution functions determined by CTEQ at low are used as
inputs to test the validity of the valon model. The valon distributions in a
nucleon are first found to be nearly independent. The parton distribution
in a valon are shown to be consistent with being universal, independent of the
valon type. The momentum fractions of the partons in the valon add up
separately to one. These properties affirm the validity of the valon model. The
various distributions are parameterized for convenient application of the
model.Comment: 9 pages + 9 figures in ep
Nucleon participants or quark participants?
We show that centrality dependence of charged particle pseudorapidity density
at midrapidity in Au+Au collisions at RHIC is well described as proportional to
We show that centrality dependence of charged particle pseudorapidity density
at midrapidity in Au+Au collisions at RHIC is well described as proportional to
the number of participating constituent quarks. In this approach there is no
need for an additional contribution from hard processes usually considered in
the models based on the number of the nucleon participants.Comment: 3 pages, 4 figures, latex, version accepted for publication in
Phys.Rev.
Fluctuation of Gaps in Hadronization at Phase Transition
Event-by-event fluctuations of hadronic patterns in heavy-ion collisions are
studied in search for signatures of quark-hadron phase transition. Attention is
focused on a narrow strip in the azimuthal angle with small . The
fluctuations in the gaps between particles are quantified by simple measures. A
scaling exponent is shown to exist around . An index is
shown to characterize the critical fluctuation; it is a numerical constant
. All the measures considered in this gap analysis are
experimentally observable. Whether or not the theoretical predictions, based on
simulations using 2-dimensional Ising model, are realistic for heavy-ion
collisions, analysis of the experimental data suggested here should be carried
out, since the existence of a scaling behavior is of interest in its own right.Comment: 10 pages LaTex + 8 eps figure
Universal behavior of multiplicity differences in quark-hadron phase transition
The scaling behavior of factorial moments of the differences in
multiplicities between well separated bins in heavy-ion collisions is proposed
as a probe of quark-hadron phase transition. The method takes into account some
of the physical features of nuclear collisions that cause some difficulty in
the application of the usual method. It is shown in the Ginzburg-Landau theory
that a numerical value of the scaling exponent can be determined
independent of the parameters in the problem. The universality of
characterizes quark-hadron phase transition, and can be tested directly by
appropriately analyzed data.Comment: 15 pages, including 4 figures (in epsf file), Latex, submitted to
Phys. Rev.
A generalization of Alternating Sign Matrices
In alternating sign matrices the first and last nonzero entry in each row and
column is specified to be +1.
Such matrices always exist. We investigate a generalization by specifying
independently the sign of the first and last nonzero entry in each row and
column to be either a +1 or a -1. We determine necessary and sufficient
conditions for such matrices to exist.Comment: 14 page
Fragmentation or Recombination at High p_T?
All hadronization processes, including fragmentation, are shown to proceed
through recombination. The shower partons in a jet turn out to play an
important role in describing the p_T spectra of hadrons produced in heavy-ion
collisions. Due to the recombination of the shower partons with the soft
thermal partons, the structure of jets produced in AA collisions is not the
same as that of jets produced in pp collisions.Comment: Talk given at Quark Matter 200
Charm Correlation as a Diagnostic Probe of Quark Matter
The use of correlation between two open-charm mesons is suggested to give
information about the nature of the medium created in heavy-ion collisions.
Insensitivity to the charm production rate is achieved by measuring normalized
cumulant. The acollinearity of the D momenta in the transverse plane is a
measure of the medium effect. Its dependence on nuclear size or E_T provides a
signature for the formation of quark matter.Comment: 12 pages, no figure
Dihadron Correlation in Jets Produced in Heavy-Ion Collisions
The difference between the structures of jets produced in heavy-ion and
hadronic collisions can best be exhibited in the correlations between particles
within those jets. We study the dihadron correlations in jets in the framework
of parton recombination. Two types of triggers, and proton, are
considered. It is shown that the recombination of thermal and shower partons
makes the most important contribution to the spectra of the associated
particles at intermediate . In collisions the only significant
contribution arises from shower-shower recombination, which is negligible in
heavy-ion collisions. Moments of the associated-particle distributions are
calculated to provide simple summary of the jet structures for easy comparison
with experiments.Comment: 24 pages in Latex + 5 figure
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