270 research outputs found
Validity and Failure of the Boltzmann Weight
The dynamics and thermostatistics of a classical inertial XY model,
characterized by long-range interactions, are investigated on -dimensional
lattices ( and 3), through molecular dynamics. The interactions between
rotators decay with the distance like~ (), where and respectively correspond to the
nearest-neighbor and infinite-range interactions. We verify that the momenta
probability distributions are Maxwellians in the short-range regime, whereas
-Gaussians emerge in the long-range regime. Moreover, in this latter regime,
the individual energy probability distributions are characterized by long
tails, corresponding to -exponential functions. The present investigation
strongly indicates that, in the long-range regime, central properties fall out
of the scope of Boltzmann-Gibbs statistical mechanics, depending on and
through the ratio .Comment: 10 pages, 6 figures. To appear in EP
Tsallis Distribution Decorated With Log-Periodic Oscillation
In many situations, in all branches of physics, one encounters power-like
behavior of some variables which are best described by a Tsallis distribution
characterized by a nonextensivity parameter and scale parameter .
However, there exist experimental results which can be described only by a
Tsallis distributions which are additionally decorated by some log-periodic
oscillating factor. We argue that such a factor can originate from allowing for
a complex nonextensivity parameter . The possible information conveyed by
such an approach (like the occurrence of complex heat capacity, the notion of
complex probability or complex multiplicative noise) will also be discussed.Comment: 17 pages, 1 figure. The content of this article was presented by Z.
Wlodarczyk at the SigmaPhi2014 conference at Rhodes, Greece, 7-11 July 2014.
To be published in Entropy (2015
Some Open Points in Nonextensive Statistical Mechanics
We present and discuss a list of some interesting points that are currently
open in nonextensive statistical mechanics. Their analytical, numerical,
experimental or observational advancement would naturally be very welcome.Comment: 30 pages including 6 figures. Invited paper to appear in the
International Journal of Bifurcation and Chao
Unified model for network dynamics exhibiting nonextensive statistics
We introduce a dynamical network model which unifies a number of network
families which are individually known to exhibit -exponential degree
distributions. The present model dynamics incorporates static (non-growing)
self-organizing networks, preferentially growing networks, and (preferentially)
rewiring networks. Further, it exhibits a natural random graph limit. The
proposed model generalizes network dynamics to rewiring and growth modes which
depend on internal topology as well as on a metric imposed by the space they
are embedded in. In all of the networks emerging from the presented model we
find q-exponential degree distributions over a large parameter space. We
comment on the parameter dependence of the corresponding entropic index q for
the degree distributions, and on the behavior of the clustering coefficients
and neighboring connectivity distributions.Comment: 11 pages 8 fig
Asymptotically scale-invariant occupancy of phase space makes the entropy Sq extensive
Phase space can be constructed for equal and distinguishable subsystems
that could be (probabilistically) either {\it weakly} (or {\it "locally"})
correlated (e.g., independent, i.e., uncorrelated), or {\it strongly} (or {\it
globally}) correlated. If they are locally correlated, we expect the
Boltzmann-Gibbs entropy to be {\it
extensive}, i.e., for . In particular, if
they are independent, is {\it strictly additive}, i.e., . However, if the subsystems are globally correlated, we
expect, for a vast class of systems, the entropy (with ) for some special value of to be the
one which extensive (i.e., for ).Comment: 15 pages, including 9 figures and 8 Tables. The new version is
considerably enlarged with regard to the previous ones. New examples and new
references have been include
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