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 $\Delta y$. The fluctuations in the gaps between particles are quantified by simple measures. A scaling exponent $\alpha$ is shown to exist around $T_c$. An index $\xi$ is shown to characterize the critical fluctuation; it is a numerical constant $\xi=0.05\pm0.01$. 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 $Q^2$ dependence of the parameters is given by polynomials of $\ln Q^2$ for a wide range of $Q^2$.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, $xg_1^p$, and its first moment, $\Gamma_{1}^p$, are in good agreement with the experimental data for a range of values of $Q^{2}$. 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 $A$ and the partonic structure functions inside the valon, we can calculate the nuclear structure function in $x$ space. The results for nuclear structure-function ratio $F_2^A/F_2^D$ at some values of $A$ are in good agreement with the experimental data.Comment: To be published in Int. Journal of Modern Phys.