456 research outputs found
Centrality Scaling of the Distribution of Pions
From the preliminary data of PHENIX on the centrality dependence of the
spectrum in at midrapidity in heavy-ion collisions, we show that
a scaling behavior exists that is independent of the centrality. It is then
shown that degrades with increasing exponentially with a
decay constant that can be quantified. A scaling distribution in terms of an
intuitive scaling variable is derived that is analogous to the KNO scaling. No
theoretical models are used in any part of this phenomenological analysis.Comment: 4 pages RevTex, 5 figures include
A Scaling Hypothesis for the Spectral Densities in the O(3) Nonlinear Sigma-Model
A scaling hypothesis for the n-particle spectral densities of the O(3)
nonlinear sigma-model is described. It states that for large particle numbers
the n-particle spectral densities are ``self-similar'' in being basically
rescaled copies of a universal shape function. This can be viewed as a
2-dimensional, but non-perturbative analogue of the KNO scaling in QCD.
Promoted to a working hypothesis, it allows one to compute the two point
functions at ``all'' energy or length scales. In addition, the values of two
non-perturbative constants (needed for a parameter-free matching of the
perturbative and the non-perturbative regime) are determined exactly.Comment: 9 Pages, Latex, 3 Postscript Figure
The Orbifolds of Permutation-Type as Physical String Systems at Multiples of c=26 IV. Orientation Orbifolds Include Orientifolds
In this fourth paper of the series, I clarify the somewhat mysterious
relation between the large class of {\it orientation orbifolds} (with twisted
open-string CFT's at ) and {\it orientifolds} (with untwisted open
strings at ), both of which have been associated to division by
world-sheet orientation-reversing automorphisms. In particular -- following a
spectral clue in the previous paper -- I show that, even as an {\it interacting
string system}, a certain half-integer-moded orientation orbifold-string system
is in fact equivalent to the archetypal orientifold. The subtitle of this
paper, that orientation orbifolds include and generalize standard orientifolds,
then follows because there are many other orientation orbifold-string systems
-- with higher fractional modeing -- which are not equivalent to untwisted
string systems.Comment: 22 pages, typos correcte
Conformal Moduli and b-c Pictures for NSR Strings
We explore the geometry of the superconformal moduli of the NSR superstring
theory in order to construct the consistent sigma-model for the NSR strings,
free of picture-changing ambiguities. The sigma-model generating functional is
constructed by the integration over the bosonic and anticommuting moduli,
corresponding to insertions of the vertex operators in scattering amplitudes.
In particular, the integration over the bosonic moduli results in the
appearance of picture-changing operators for the b-c system. Important example
of the b-c pictures involves the unintegrated and integrated forms of the
vertex operators. We derive the BRST-invariant expressions for the b-c
picture-changing operators for open and closed strings and study some of their
properties. We also show that the superconformal moduli spaces of the NSR
superstring theory contain the global singularities, leading to the appearance
of non-perturbative solitonic D-brane creation operators.Comment: 22 pages, references adde
Multiplicity dependence of identical particle correlations in the quantum optical approach
Identical particle correlations at fixed multiplicity are consideres in the
presence of chaotic and coherent fields. The multiplicity distribution,
one-particle momentum density, and two-particle correlation function are
obtained based on the diagrammatic representation for cmulants in
semi-inclusive events. Our formulation is applied to the analysis of the
experimental data on the multiplicity dependence of correlation functions
reported by the UA1 and the OPAL Collaborations.Comment: 14 pages, 7 figure
Universal features of the off-equilibrium fragmentation with the Gaussian dissipation
We investigate universal features of the off-equilibrium sequential and
conservative fragmentation processes with the dissipative effects which are
simulated by the Gaussian random inactivation process. The relation between the
fragment multiplicity scaling law and the fragment size distribution is studied
and a dependence of scaling exponents on the parameters of fragmentation and
inactivation rate functions is established.Comment: 10 pages, 2 figure
Energy Conservation Constraints on Multiplicity Correlations in QCD Jets
We compute analytically the effects of energy conservation on the
self-similar structure of parton correlations in QCD jets. The calculations are
performed both in the constant and running coupling cases. It is shown that the
corrections are phenomenologically sizeable. On a theoretical ground, energy
conservation constraints preserve the scaling properties of correlations in QCD
jets beyond the leading log approximation.Comment: 11 pages, latex, 5 figures, .tar.gz version avaliable on
ftp://www.inln.unice.fr
Fluid Dynamics of NSR Strings
We show that the renormalization group flows of the massless superstring
modes in the presence of fluctuating D-branes satisfy the equations of fluid
dynamics.In particular, we show that the D-brane's U(1) field is related to the
velocity function in the Navier-Stokes equation while the dilaton plays the
role of the passive scalar advected by the turbulent flow. This leads us to
suggest a possible isomorphism between the off-shell superstring theory in the
presence of fluctuating branes and the fluid mechanical degrees of freedom.Comment: 24 pages Dedicated to the memory of Ian Koga
Measuring the Charged Particle Multiplicity with ALICE
The charged particle multiplicity distribution is one of the first
measurements that ALICE will be able to perform. The knowledge of this basic
property at a new energy is needed to configure Monte Carlo generators
correctly with the aim of understanding the background of other, especially
rare, processes including new physics. It allows to study the scaling behaviour
and to verify model predictions. The unfolding of the measurement is a
non-trivial task due to the finite precision and acceptance of the detector.
Solutions are based on chi2 minimization or iteratively using Bayes' theorem.
Both approaches to unfold the spectrum are presented. Furthermore, the
capabilities of the SPD fast OR trigger are shown that enable physics at very
high multiplicities.Comment: Proceedings of poster presentation at Quark Matter 2008, 20th
International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions in
Jaipur, India; to be published in Indian Journal of Physics; 4 pages, 4
figure
Parton Branching in Color Mutation Model
The soft production problem in hadronic collisions as described in the
eikonal color mutation branching model is improved in the way that the initial
parton distribution is treated. Furry branching of the partons is considered as
a means of describing the nonperturbative process of parton reproduction in
soft interaction. The values of all the moments, and , for q=2,...,5,
as well as their energy dependences can be correctly determined by the use of
only two parameters.Comment: 8 pages (LaTeX) + 2 figures (ps files), submitted to Phys. Rev.
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