5,891 research outputs found
Cumulants of QCD Multiplicity Distributions in Small Phase Space Bins
It is shown that, as functions of their rank, cumulants of QCD multiplicity
distributions in small phase space bins possess the quasi- oscillating behavior
similar to that found for them in the total rapidity range. First minimum moves
to lower ranks for smaller bins. For the total rapidity range, it moves to
higher ranks with energy increase. The running property of the QCD coupling
constant is in charge of these effects which can be verified in experiment.Comment: 7 pages, no Figs, preprint IP-ASTP-19; FIAN-TD 94/
The medium in heavy-ion collisions
The nuclear index of refraction, the density of partons, their free path
length and energy loss in the matter created in heavy-ion collisions at RHIC
are estimated within the suggestion that the emission of Cherenkov gluons is
responsible for the observed two-bump structure of the angular distribution of
hadrons belonging to the companion (away-side) jet.Comment: 3 pages, 1 Figur
On distribution of number of trades in different time windows in the stock market
Properties of distributions of the number of trades in different intraday
time intervals for five stocks traded in MICEX are studied. The dependence of
the mean number of trades on the capital turnover is analyzed. Correlation
analysis using factorial and moments demonstrates the multifractal nature
of these distributions as well as some peculiar changes in the correlation
pattern. Guided by the analogy with the analysis of particle multiplicity
distributions in multiparticle production at high energies, an evolution
equation relating changes in capital turnover and a number of trades is
proposed. We argue that such equation can describe the observed features of the
distribution of the number of trades in the stock market.Comment: LaTeX, 6 figure
Cherenkov Glue in Opaque Nuclear Medium
The spectrum of Cherenkov gluons is calculated within the framework of
in-medium QCD. It is compared with experimental data on the double-humped
structure around the away-side jet obtained at RHIC. The values of the real and
imaginary parts of the nuclear permittivity are obtained from these fits. It is
shown that accounting for an additional smearing due to resonance-like
production of final hadrons allows to achieve an agreement with experimental
data
Hadron Multiplicities
We review results on hadron multiplicities in high energy particle
collisions. Both theory and experiment are discussed. The general procedures
used to describe particle multiplicity in Quantum Chromodynamics (QCD) are
summarized. The QCD equations for the generating functions of the multiplicity
distributions are presented both for fixed and running coupling strengths. The
mean multiplicities of gluon and quark jets, their ratio, higher moments, and
the slopes of multiplicities as a function of energy scale, are among the main
global features of multiplicity for which QCD results exist. Recent data from
high energy e+e- experiments, including results for separated quark and gluon
jets, allow rather direct tests of these results. The theoretical predictions
are generally quite successful when confronted with data. Jet and subjet
multiplicities are described. Multiplicity in limited regions of phase space is
discussed in the context of intermittency and fractality. The problem of
singularities in the generating functions is formulated. Some special features
of average multiplicities in heavy quark jets are described.Comment: 140 pages, 33 figures, version for Physics Report
Soft and hard processes in QCD
QCD equations for the generating functions are applied to separate soft and
hard jets in -processes of multiparticle production. The dependence of
average multiplicities and higher moments of multiplicity distributions of
particles created in a "newly born" soft subjets on the share of energy devoted
to them is calculated in fixed coupling gluodynamics. This dependence is the
same as for the total multiplicity up to a constant factor if soft jets are
defined as those carrying out a fixed share of initial energy at all energies.
The constant factor depends on this share in a non-trivial way. Other
definitions are also proposed. The relation between these quantities for soft
and hard processes is discussed.Comment: 6 pages, no Figures, LATEX, more detailed discussion of definitions
and proposals for experiment is give
Measuring Hadronization Length in e^+ e^- \rightarrow K^0 {\bar{K}}^0 \gamma
We propose to study the space-time picture of hadronization by looking at the
angular distribution of photons emitted in the process e^+ e^- \rightarrow K^0
{\bar{K}}^0 \gamma at DA{\Phi}NE energies. it is shown that the angular
distributions are quite sensitive to the hadronization length.Comment: 5 pages, CERN-TH-7200/94, BI-TP 94/04, March 199
The background for Cherenkov gluons at RHIC and LHC energies
The pseudorapidity distribution of centers of dense isolated groups of
particles in HIJING model is determined. It can be considered as the background
for Cherenkov gluons. If peaks over this background were found in experiment,
they would indicate the onset of new collective effects.Comment: 4 pages, 2 figures, uses espcrc1.sty; QM 2005 contributio
High E jets and double scattering
The recently found excess of high E jets over current QCD predictions is
attributed to gluon radiation at double scattering process inside a nucleon.
The order of magnitude estimate of the cross section fits experimental findings
rather well. The specific features of the process are discussed. Various
similar hadronic effects related to the short radiation length are described.Comment: 6 pages, plain LaTe
Ring-like events: Cherenkov gluons or Mach waves?
Similar to electromagnetic forces, strong interactions might induce such
collective effects as Cherenkov and Mach waves. Their conical structure would
be responsible for specific ring-like events. The theoretical and experimental
arguments in favor of these phenomena are discussed and their most important
features are described.Comment: 12 pages, 5 figures, LATEX, misprint correcte
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