25 research outputs found
Questions and Remarks About Clans in Multiparticle Dynamics
The fact that several important effects in multiparticle dynamics, on which
QCD has not yet satisfactory predictions, have been interpreted in terms of the
validity of negative binomial (Pascal) regularity and related clan properties
at the level of simpler substructures, raises intriguing questions on clan
properties in all classes of collisions, the main one being whether clans are
observable objects or merely a mathematical concept. We approach this problem
by studying clan masses and rapidity distributions in each substructure for
e+e- annihilation and hh collisions, and find that such properties can indeed
characterise the different components. These results support the idea that
clans could be observable, a challenging problem for future experiments.Comment: 11 pages; 3 figures; latex 2e and amsmat
Multiple Interactions and the Structure of Beam Remnants
Recent experimental data have established some of the basic features of
multiple interactions in hadron-hadron collisions. The emphasis is therefore
now shifting, to one of exploring more detailed aspects. Starting from a brief
review of the current situation, a next-generation model is developed, wherein
a detailed account is given of correlated flavour, colour, longitudinal and
transverse momentum distributions, encompassing both the partons initiating
perturbative interactions and the partons left in the beam remnants. Some of
the main features are illustrated for the Tevatron and the LHC.Comment: 69pp, 33 figure
Multifractal Multiplicity Distribution in Bunching-Parameter Analysis
A new multiplicity distribution with multifractal properties which can be
used in high-energy physics and quantum optics is proposed. It may be
considered as a generalization of the negative-binomial distribution. We find
the structure of the generating function for such distribution and discuss its
properties.Comment: LaTex, 12 pages, cite.st
A Unified Treatment of High Energy Interactions
It is well known that high energy interactions as different as
electron-positron annihilation, deep inelastic lepton-nucleon scattering,
proton-proton interactions, and nucleus-nucleus collisions have many features
in common. Based upon this observation, we construct a model for all these
interactions, which relies on the fundamental hypothesis that the behavior of
high energy interactions is universal.Comment: 4 pages, LaTeX created with LyX, 8 figures, more figures at
http://www-subatech.in2p3.fr/~theo/nexus/example
Centrality and dE_{T}/d\etadN_{ch}/d\eta$ in Heavy Ion Collisions at Mid-Rapidity
The PHENIX experiment at RHIC has measured transverse energy and charged
particle multiplicity at mid-rapidity in Au + Au collisions at
= 19.6, 130, 62.4 and 200 GeV as a function of centrality. The presented
results are compared to measurements from other RHIC experiments, and
experiments at lower energies. The dependence of
and per pair of participants is consistent with logarithmic
scaling for the most central events. The centrality dependence of
and is similar at all measured incident
energies. At RHIC energies the ratio of transverse energy per charged particle
was found independent of centrality and growing slowly with . A
survey of comparisons between the data and available theoretical models is also
presented.Comment: Proccedings of the Workshop: Focus on Multiplcity at Bari, Italy,
June 17-19,2004. To be submitted to the Jornal of Physics, "Conference
series". Includes: 20 Pages, 15 figures, 3 Tables, 80 Referencie
Strangeness and Quark Gluon Plasma
A brief summary of strangeness mile stones is followed by a chemical
non-equilibrium statistical hadronization analysis of strangeness results at
SPS and RHIC. Strange particle production in AA interactions at
\sqrt{s_{NN}}\ge 8.6 GeV can be understood consistently as originating from the
deconfined quark--gluon plasma in a sudden hadronization process. Onset of QGP
formation as function of energy is placed in the beam energy interval 10--30A
GeV/c. Strangeness anomalies at LHC are described.Comment: 30 pages including numerouse figures, tables. Opening Lecture:
Strangeness and Quark Gluon Plasma -- what has been learned so far and where
do we go at SQM2003, North Carolina, March 2003, submitted to J. Phys.
Forward-Backward Correlations and Event Shapes as probes of Minimum-Bias Event Properties
Measurements of inclusive observables, such as particle multiplicities and
momentum spectra, have already delivered important information on
soft-inclusive ("minimum-bias") physics at the Large Hadron Collider. In order
to gain a more complete understanding, however, it is necessary to include also
observables that probe the structure of the studied events. We argue that
forward-backward (FB) correlations and event-shape observables may be
particulary useful first steps in this respect. We study the sensitivity of
several different types of FB correlations and two event shape variables -
transverse thrust and transverse thrust minor - to various sources of
theoretical uncertainty: multiple parton interactions, parton showers, colour
(re)connections, and hadronization. The power of each observable to furnish
constraints on Monte Carlo models is illustrated by including comparisons
between several recent, and qualitatively different, PYTHIA 6 tunes, for pp
collisions at sqrt(s) = 900 GeV.Comment: 13 page
Consistent Treatment of Soft and Hard Processes in Hadronic Interactions
The QCD improved parton model is a very successful concept to treat processes
in hadronic interactions, whenever large partonic transverse momenta are
involved. However, cross sections diverge in the limit p_T -> 0, and the usual
treatment is the definition of a lower cutoff p_T_min, such that processes with
a smaller p_T -- so-called soft processes -- are simply ignored, which is
certainly not correct for example at RHIC energies. A more consistent procedure
amounts to introduce a technical parameter Q_0^2, referred to as soft
virtuality scale, which is nothing but an artificial borderline between soft
and hard physics. We will discuss such a formalism, which coincides with the
improved parton model for high p_T processes and with the phenomenological
treatment of soft scattering, when only small virtualities are involved. The
most important aspect of our approach is that it allows to obtain a smooth
transition between soft and hard scattering, and therefore no artificial
dependence on a cutoff parameter should appear.Comment: 19 pages, 19 figure
Recent results from the UA5 experiment at the CERN panti p collider
SIGLECopy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman
Diffraction dissociation at the CERN pulsed collider at c.m. energies of 900 and 200 GeV
SIGLEAvailable from Bonn Univ. (DE). Physikalisches Inst. / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman