3,882 research outputs found
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
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.
Renormalization group approach to multiparticle density fluctuations
An iterative procedure is developed with the aim of constructing homogeneity
rules for the distribution P(rho,delta) of the particle density rho at
resolution scale delta. A single iteration step consists of a change in the
normalization point of P(rho,delta) followed by a rescaling. Similar
transformation rule is introduced for density fluctuations contaminated by
Poisson noise. Application of the iterative procedure is given for the
Ginzburg-Landau description of phase-transition from the quark-gluon plasma and
for random cascading models.Comment: 11 pages REVTeX, 1 figure include
Evolution of shower parton distributions in a jet from quark recombination model
The evolution of shower parton distributions in a jet is investigated in the
framework of quark recombination model. The distributions are parameterized and
the dependence of the parameters is given by polynomials of for
a wide range of .Comment: 5 pages in RevTeX, 3 figures in ep
Void Analysis of Hadronic Density Fluctuations at Phase Transition
The event-to-event fluctuations of hadron multiplicities are studied for a
quark system undergoing second-order phase transition to hadrons. Emphasis is
placed on the search for an observable signature that is realistic for
heavy-ion collisions. It is suggested that in the 2-dimensional y-phi space the
produced particles selected in a very narrow p_T window may exhibit clustering
patterns even when integrated over the entire emission time. Using the Ising
model to simulate the critical phenomenon and taking into account a p_T
distribution that depends on the emission time, we study in the framework of
the void analysis proposed earlier and find scaling behavior. The scaling
exponents turn out to be larger than the ones found before for pure
configurations without mixing. The signature is robust in that it is
insensitive to the precise scheme of simulating time evolution. Thus it should
reveal whether or not the dense matter created in heavy-ion collisions is a
quark-gluon plasma before hadronization.Comment: 11 pages in LaTeX + 6 figures in p
Next-to-Leading order approximation of polarized valon and parton distributions
Polarized parton distributions and structure functions of the nucleon are
analyzed in the improved valon model. The valon representation provides a model
to represent hadrons in terms of quarks, providing a unified description of
bound state and scattering properties of hadrons. Polarized valon distributions
are seen to play an important role in describing the spin dependence of parton
distributions in the leading order (LO) and next-to-leading order (NLO)
approximations. In the polarized case, a convolution integral is derived in the
framework of the valon model. The Polarized valon distribution in a proton and
the polarized parton distributions inside the valon are necessary to obtain the
polarized parton distributions in a proton. Bernstein polynomial averages are
used to extract the unknown parameters of the polarized valon distributions by
fitting to the available experimental data. The predictions for the NLO
calculations of the polarized parton distributions and proton structure
functions are compared with the LO approximation. It is shown that the results
of the calculations for the proton structure function, , and its first
moment, , are in good agreement with the experimental data for a
range of values of . Finally the spin contribution of the valons to the
proton is calculated.Comment: 22 pages, 7 figures. Published in Journal of High Energy Physics
(JHEP
Polymer Adsorption on Disordered Substrate
We analyze the recently proposed "pattern-matching" phase of a Gaussian
random heteropolymer adsorbed on a disordered substrate [S. Srebnik, A.K.
Chakraborty and E.I. Shakhnovich, Phys. Rev. Lett. 77, 3157 (1996)]. By mapping
the problem to that of a directed homopolymer in higher-dimensional random
media, we show that the pattern-matching phase is asymptotically weakly
unstable, and the large scale properties of the system are given by that of an
adsorbed homopolymer.Comment: 5 pages, RevTeX, text also available at http://matisse.ucsd.edu/~hw
The Exact N-point Generating Function in Polyakov-Burgers Turbulence
We find the exact N-point generating function in Polyakov's approach to
Burgers turbulence.Comment: 7 pages,Latex,no figure
Nuclear Parton Densities and Structure Functions
We calculate nuclear parton distribution functions (PDFs), using the
constituent quark model. We find the bounded valon distributions in a nuclear
to be related to free valon distributions in a nucleon. By using improved
bounded valon distributions for a nuclear with atomic number and the
partonic structure functions inside the valon, we can calculate the nuclear
structure function in space. The results for nuclear structure-function
ratio at some values of are in good agreement with the
experimental data.Comment: To be published in Int. Journal of Modern Phys.
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