1,239 research outputs found
The collective behavior of the partons and its influence on the jet suppression in heavy ion collisions
We discuss the physical picture that a parton interaction with a coherent
group of partons can lead to more jet quenching effect in the hot and dense
matter created by heavy ion collisions at RHIC and LHC energies. We came to
this picture after analyzing the behaviour of the nuclear modification factor
as a function of for the charged particles produced in the most central
Pb-Pb collisions at 2.76 A TeV. In the interval, the values of the
factor as a function of increases almost linearly with a slope is very
close to expected one for the inverse Compton effect. Around
GeV/c, a regime change occurs, which is characteristic for the phenomenon. We
propose that this similarity can be explained by the inverse Compton effect for
partons, which occurs via a collective parton group formation ( through the
appearance of a new string as a result of the fusion of strings) and its
interactions with single partons in the interval of . In
the case of a coherent collision with a parton that has a lower energy than the
group, the parton can gain energy through the inverse Compton effect, resulting
in its acceleration and shifting to the region of GeV/c. After losing
a significant part of its energy new string will decay into partons with lower
energies - slowed partons in the interval of . This enhancement
in the jet quenching can be observed in the interval of .Comment: 8 pages, 1 figure, 1 tabl
Entropy and multifractal analysis of multiplicity distributions from pp simulated events up to LHC energies
Using three different Monte Carlo generators of high energy proton-proton
collisions (HIJING, NEXUS, and PSM) we study the energy dependence of
multiplicity distributions of charged particles including the LHC energy range.
Results are used for calculation of the information entropy, Renyi's dimensions
and other multifractal characteristics of particle production.Comment: 15 pages, 8 figure
On some inverse problems in nuclear physics
Some inverse problems in high-energy physics, neutron diffraction and NMR
spectroscopy are discussed. To solve them, the Fourier integrated
transformation method and the Maximum Entropy Technique (MENT) were used. The
integrated images of experimental distributions are shown to be informative
when determining the space-time parameters of a particle generation zone and
when analysing blurred spectra. The efficiency of the above methods was checked
by comparing relevant results with the results obtained independently
The maximum entropy tecniques and the statistical description of systems
The maximum entropy technique (MENT) is used to determine the distribution
functions of physical values. MENT naturally combines required maximum entropy,
the properties of a system and connection conditions in the form of
restrictions imposed on the system. It can, therefore, be employed to
statistically describe closed and open systems. Examples in which MENT is used
to describe equilibrium and non-equilibrium states, as well as steady states
that are far from being in thermodynamic equilibrium, are discussed
Search for periodicities in experimental data using an autoregression data model
To process data obtained during interference experiments in high-energy
physics, methods of spectral analysis are employed. Methods of spectral
analysis, in which an autoregression model of experimental data is used, such
as the maximum entropy technique as well as Pisarenko and Prony's method, are
described. To show the potentials of the methods, experimental and simulated
hummed data are discussed as an example
Searching for the properties of nuclear matter using proton-carbon and deuteron-carbon collisions at 4.2 a gev/c
The present work reports the use of nuclear transparency effect of protons in
proton and deuteron carbon interactions at 4.2 A GeV/c to get information about
the states of nuclear matter. The half angle technique is used to extract the
information on nuclear transparency. The results are compared with Dubna
version of Cascade model. The average values of multiplicity, momentum and
transverse momentum of protons are analyzed as a function of the number of
identified protons in an event. We observed some evidence and trends in the
data which could be considered as transparency effect. Analysis of the results
shows that the leading effect is the basis of the observed transparency. Some
contribution to the observed effect could be the existing short range
correlations and the scaling power law s^-N, for exclusive two body hard
scattering.Comment: 7 pages, 2 figure
The meaning behind observed regions at the LHC energies
We argue that distribution data from the LHC on the invariant
differential yield of the charged primary particles in collisions at
and in collisions at
with 6 centrality bins contains several regions
with special properties. These distributions were analysed by fitting the data
with exponential functions. We conclude that the regions reflect features of
fragmentation and hadronization of partons through the string dynamics. The
nuclear transparency results in negligible influence of the medium in the III
region (), which has highest values. The effects and
changes by the medium start to appear weakly in the II region () and become stronger in the I region () . It
seems that the II region has highest number of strings. The increase in string
density in this region could lead to fusion of strings, appearance of a new
string and collective behaviour of the partons in the most central collisions.
These phenomena can explain anomalous behaviour of the Nuclear Modification
Factor in the II region. We propose the II region as a possible area of Quark
Gluon Plasma formation through string fusion. The first regions are the
ones with the maximum number of hadrons and minimum number of strings due to
direct hadronization of the low energy strings into two quark systems - mesons.Comment: 20 pages with 10 figures and 3 table
Search for a Signal on Phase Transitions of Strongly Interacting Matter using the Nuclear Transparency Effect
We discuss that the results coming from the central experiments confirm the
results which had been obtained for the behavior of the K+-meson's temperature
behavior as a function of the energy in SPS energy range. To see the "horn" for
the behavior of the ratio for average values of K+- to pi+- mesons as a
function of centrality the new more rich experimental data are required. The
data can be obtained with NICA/MPD setup. The existing of the QCD critical
point could be identified by using the nuclear transparency effect as a
function of the centrality.Comment: 6 pages, 5 figure
Chiral Separation effect in non-homogeneous systems
We discuss chiral separation effect in the systems with spatial non -
homogeneity. It may be caused by non - uniform electric potential or by another
reasons, which do not, however, break chiral symmetry of an effective low
energy theory. Such low energy effective theory describes quasiparticles close
to the Fermi surfaces. In the presence of constant external magnetic field the
non - dissipative axial current appears. It appears that its response to
chemical potential and magnetic field (the CSE conductivity) is universal. It
is robust to smooth modifications of the system and is expressed through an
integral over a surface in momentum space that surrounds all singularities of
the Green function. In itself this expression represents an extension of the
topological invariant protecting Fermi points to the case of inhomogeneous
systems.Comment: Latex, 31 pages, 1 Figur
Study of the behavior of the nuclear modification factor in freeze-out state
We have studied the behaviour of the nuclear modification factor as a
function of centrality, chemical baryon potential and thermal freeze out
temperature using the data coming from the Fast Hadron Freezeout Generator.
Considering two ways of NMF definition, namely the ratio of meson yields and
ratio of baryons yield, we considered two associates effects (for percolation
cluster formation) to identify it; appearance of the anomalous nuclear
transparency and light nuclei production. In this paper we have used the
behaviour of nuclear modification factor as a function of different physical
parameters to get the information of the behavior of nuclear transparency
effect and the nuclear coalescence in freezeout state. We have chosen different
generators for this purpose. Here we have used the simulated data for Au-Au
collisions at RHIC energies coming from the FASTMC Model. This model is very
good in freezeout state.Comment: 4 figures, 4 pages, To appear in the Proceeding of XXVIII Physics in
Collision- Perugia, Italy, June 25-28, 200
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