39 research outputs found
How the nuclear Fermi motion plus a simple statistical model explains the EMC effect
We present calculation of influence caused by nucleon Fermi motion on the
parton distributions in nuclei. Our approach is based on the model where
momenta of valence partons have some primordial distribution inside the hadron
at rest, which is either provided by a statistical considerations or calculated
using spherically symmetric Gaussian distribution with a width derived from the
Heisenberg uncertainty relation. The sea parton contribution emerges from the
similar Gaussian distribution with a width dictated by the presence of virtual
pions in hadron. We show that the influence of Fermi motion changes
substantially the nucleonic structure function inside the nucleus in the right
direction and therefore should be considered seriously in all attempts devoted
to explain the experimentally observed EMC effect for .Comment: Contribution to PANIC 2002 conference, Sept. 30 - October 4, 2002,
Osaka, Japan. Some misprints correcte
Nonextensive quasiparticle description of QCD matter
The dynamics of QCD matter is often described using effective mean field (MF)
models based on Boltzmann-Gibbs (BG) extensive statistics. However, such matter
is normally produced in small packets and in violent collisions where the usual
conditions justifying the use of BG statistics are not fulfilled and the
systems produced are not extensive. This can be accounted for either by
enriching the original dynamics or by replacing the BG statistics by its
nonextensive counterpart described by a nonextensivity parameter (for
one returns to the extensive situation). In this work we investigate
the interplay between the effects of dynamics and nonextensivity. Since the
complexity of the nonextensive MF models prevents their simple visualization,
we instead use some simple quasi-particle description of QCD matter in which
the interaction is modelled phenomenologically by some effective fugacities,
. Embedding such a model in a nonextensive environment allows for a
well-defined separation of the dynamics (represented by ) and the
nonextensivity (represented by ) and a better understanding of their
relationship.Comment: Thorougly reworked version published in Symmetry 2019, 11(3), 401, as
contribution to the Special Issue Nambu--Jona-Lassinio model and its
applications; 22 pages, 7 figure
Nonlinear statistical effects in relativistic mean field theory
We investigate the relativistic mean field theory of nuclear matter at finite
temperature and baryon density taking into account of nonlinear statistical
effects, characterized by power-law quantum distributions. The analysis is
performed by requiring the Gibbs conditions on the global conservation of
baryon number and electric charge fraction. We show that such nonlinear
statistical effects play a crucial role in the equation of state and in the
formation of mixed phase also for small deviations from the standard
Boltzmann-Gibbs statistics.Comment: 9 pages, 5 figures. arXiv admin note: substantial text overlap with
arXiv:1005.4643 and arXiv:0912.460
Equivalence of volume and temperature fluctuations in power-law ensembles
Relativistic particle production often requires the use of Tsallis statistics
to account for the apparently power-like behavior of transverse momenta
observed in the data even at a few GeV/c. In such an approach this behavior is
attributed to some specific intrinsic fluctuations of the temperature in
the hadronizing system and is fully accounted by the nonextensivity parameter
. On the other hand, it was recently shown that similar power-law spectra
can also be obtained by introducing some specific volume fluctuations,
apparently without invoking the introduction of Tsallis statistics. We
demonstrate that, in fact, when the total energy is kept constant, these volume
fluctuations are equivalent to temperature fluctuations and can be derived from
them. In addition, we show that fluctuations leading to multiparticle power-law
Tsallis distributions introduce specific correlations between the considered
particles. We then propose a possible way to distinguish the fluctuations in
each event from those occurring from event-to-event. This could have
applications in the analysis of high density events at LHC (and especially in
ALICE).Comment: Revised version with new figure, footnotes and references adde
Nonextensive statistical effects in the hadron to quark-gluon phase transition
We investigate the relativistic equation of state of hadronic matter and
quark-gluon plasma at finite temperature and baryon density in the framework of
the nonextensive statistical mechanics, characterized by power-law quantum
distributions. We study the phase transition from hadronic matter to
quark-gluon plasma by requiring the Gibbs conditions on the global conservation
of baryon number and electric charge fraction. We show that nonextensive
statistical effects play a crucial role in the equation of state and in the
formation of mixed phase also for small deviations from the standard
Boltzmann-Gibbs statistics.Comment: 13 pages, 10 figure
The imprints of superstatistics in multiparticle production processes
We provide an update of the overview of imprints of Tsallis nonextensive
statistics seen in a multiparticle production processes. They reveal an
ubiquitous presence of power law distributions of different variables
characterized by the nonextensivity parameter q > 1. In nuclear collisions one
additionally observes a q-dependence of the multiplicity fluctuations
reflecting the finiteness of the hadronizing source. We present sum rules
connecting parameters q obtained from an analysis of different observables,
which allows us to combine different kinds of fluctuations seen in the data and
analyze an ensemble in which the energy (E), temperature (T) and multiplicity
(N) can all fluctuate. This results in a generalization of the so called
Lindhard's thermodynamic uncertainty relation. Finally, based on the example of
nucleus-nucleus collisions (treated as a quasi-superposition of nucleon-nucleon
collisions) we demonstrate that, for the standard Tsallis entropy with degree
of nonextensivity q < 1, the corresponding standard Tsallis distribution is
described by q' = 2 - q > 1.Comment: 12 pages, 3 figures. Based on invited talk given by Z.Wlodarczyk at
SigmaPhi2011 conference, Larnaka, Cyprus, 11-15 July 2011. To be published in
Cent. Eur. J. Phys. (2011