579 research outputs found
Disk level S-matrix elements at eikonal Regge limit
We examine the calculation of the color-ordered disk level S-matrix element
of massless scalar vertex operators for the special case that some of the
Mandelstam variables for which there are no open string channel in the
amplitude, are set to zero. By explicit calculation we show that the string
form factors in the 2n-point functions reduce to one at the eikonal Regge
limit.Comment: 17 pages, Latex file, no figur
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
On modified tachyon DBI action
Recently a modification of the tachyon DBI action has been proposed in which
the tachyon carries the internal CP matrix \sigma_1 and \sigma_2. In this
paper, we find the momentum expansion of the disk level S-matrix element of
four tachyons and one gauge field in superstring theory and show that the first
and second order terms of the expansion are in perfect agreement with the above
tachyon DBI action.Comment: 15 pages, no figure; V2: typos corrected, a reference added; V3: the
final version to appear in Nucl. Phys.
Dual Shapiro-Virasoro amplitudes in the QCD dipole picture
Using the QCD dipole picture of BFKL dynamics and the conformal invariance
properties of the BFKL kernel in transverse coordinate space, we show that the
1--to--p dipole densities can be expressed in terms of dual Shapiro- Virasoro
amplitudes B{2p+2} and their generalization including non-zero conformal spins.
We discuss the possibility of an effective closed string theory of interacting
QCD dipoles.Comment: 4 (1.tex, 3.ps) files: text (tex), tables, 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
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
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
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.
Finite-dimensional analogs of string s <-> t duality and pentagon equation
We put forward one of the forms of functional pentagon equation (FPE), known
from the theory of integrable models, as an algebraic explanation to the
phenomenon known in physics as st duality. We present two simple geometrical
examples of FPE solutions, one of them yielding in a particular case the
well-known Veneziano expression for 4-particle amplitude. Finally, we interpret
our solutions of FPE in terms of relations in Lie groups.Comment: LaTeX, 12 pages, 6 eps figure
Generalised Factorial Moments and QCD Jets
{ In this paper we present a natural and comprehensive generalisation of the
standard factorial moments (\clFq) analysis of a multiplicity distribution.
The Generalised Factorial Moments are defined for all in the complex plane
and, as far as the negative part of its spectrum is concerned, could be useful
for the study of infrared structure of the Strong Interactions Theory of high
energy interactions (LEP multiplicity distribution under the ). The
QCD calculation of the Generalised Factorial Moments for negative is
performed in the double leading log accuracy and is compared to OPAL
experimental data. The role played by the infrared cut-off of the model is
discussed and illustrated with a Monte Carlo calculation. }Comment: 11pages 4 figures uuencode, LATEC, INLN 94/
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