Searcharxiv⌕ Search

arXiv subjects

Grzegorz Wilk

Publications and source records attributed to Grzegorz Wilk.

At least 55 records · Page 3Linked to original sources
arXiv2011

Remarks on the chemical composition of highest-energy cosmic rays

We present arguments aiming to reconcile the apparently contradictory results concerning the chemical composition of cosmic rays of highest energy, coming recently from Auger and HiRes collaborations. In particular, we argue that the energy dependence of the mean value and root mean square fluctuation of shower maxima distributions observed by the Auger experiment are not necessarily caused by the change of nuclear composition of primary cosmic rays.

astro-ph.HE↗
arXiv2011

Do we observe fluctuation of cross section in cosmic rays ?

It is known from some time that to explain some apparently {\it exotic events} observed in cosmic ray experiments, a deeply penetrating component in cosmic rays is needed, which, in turn, leads frequently to the nonexponential distributions of some observables. We argue that such unexpected behavior of some cosmic rays data can be most naturally explained by attributing them to the possible fluctuations of cross sections.

astro-ph.HE↗
arXiv2011

On the chemical composition of cosmic rays of highest energy

We present arguments aiming at reconciling apparently contradictory results concerning the chemical composition of cosmic rays of highest energy, coming recently from the Auger and HiRes collaborations. In particular, we argue that the energy dependence of the mean value and root mean square fluctuation of shower maxima distributions observed by the Auger experiment are not necessarily caused by the change of nuclear composition of primary cosmic rays. They could also be caused by the change of distribution of the first interaction point in the cascade. A new observable, in which this influence is strongly suppressed, is proposed and tested.

astro-ph.HE↗
arXiv2011

Generalized thermodynamic uncertainty relations

We analyze ensemble in which energy (E), temperature (T) and multiplicity (N) can all fluctuate and with the help of nonextensive statistics we propose a relation connecting all fluctuating variables. It generalizes Lindhard's thermodynamic uncertainty relations known in literature.

cond-mat.stat-mech↗
arXiv2011

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 $T$ in the hadronizing system and is fully accounted by the nonextensivity parameter $q$. 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).

hep-ph↗
arXiv2011

Composition of fluctuations of different observables

We demonstrate that description of fluctuations observed in multiparticle production processes using Tsallis statistics approach (in which fluctuations are described by the nonextensivity parameter q) leads to a specific sum rule for parameters q seen in different observables which can be verified experimentally.

hep-ph↗
arXiv2010

Power-law ensembles: fluctuations of volume or temperature ?

We present two issues here: (i) that in situation when total energy is kept constant recently proposed fluctuations of volume ensemble is equivalent to the approach using Tsallis statistics with fluctuating temperature and (ii) that the later (in which fluctuations are described by the nonextensivity parameter q) leads to the observed experimentally sum rule connecting fluctuations of different physical observables.

hep-ph↗
arXiv2009

Nonextensive critical effects in the Nambu--Jona-Lasinio model

The critical phenomena in strongly interaction matter are generally investigated using the mean-field model and are characterized by well defined critical exponents. However, such models provide only average properties of the corresponding order parameters and neglect altogether their possible fluctuations. Also the possible long range effect are neglected in the mean field approach. Here we investigate the critical behavior in the nonextensive version of the Nambu Jona-Lasinio model (NJL). It allows to account for such effects in a phenomenological way by means of a single parameter $q$, the nonextensivity parameter. In particular, we show how the nonextensive statistics influence the region of the critical temperature and chemical potential in the NJL mean field approach.

nucl-th↗
arXiv2009

Nonextensive thermal sources of cosmic rays?

The energy spectrum of cosmic rays (CR) exhibits power-like behavior with a very characteristic "knee" structure. We consider a possibility that such a spectrum could be generated by some specific nonstatistical temperature fluctuations in the source of CR with the "knee" structure reflecting an abrupt change of the pattern of such fluctuations. This would result in a generalized nonextensive statistical model for the production of CR. The possible physical mechanisms leading to these effects are discussed together with the resulting chemical composition of the CR, which follows the experimentally observed abundance of nuclei.

hep-ph↗
arXiv2009

Multiplicity fluctuations and temperature fluctuations

We argue that specific fluctuations observed in high-energy nuclear collisions can be attributed to intrinsic fluctuations of temperature of the hadronizing system formed in such processes and therefore can be described by the same nonextensivity parameter $q$ characterizing Tsallis statistics describing such systems (for $q \to 1$ one recovers the usual Boltzmann-Gibbs approach). It means that $|q-1|$, which is a direct measure of temperature fluctuations, can also be expressed by the observed mean multiplicity, $ $, and by its variance, $Var(N)$. This allows to deduce from the experimental data the system size dependence of parameter $q$ with $q = 1$ corresponding to an infinite, thermalized source with a fixed temperature, and with the observed $q > 1$ corresponding to a finite source in which both the temperature and energy fluctuate.

hep-ph↗
arXiv2009

Uncertainty relations in terms of Tsallis entropy

Uncertainty relations emerging from the Tsallis entropy are derived and discussed. In particular we found a positively defined function that saturates the so called entropic inequalities for entropies characterizing the physical states under consideration.

quant-ph↗
arXiv2009

Multiplicity fluctuations due to the temperature fluctuations in high-energy nuclear collisions

We investigate the multiplicity fluctuations observed in high-energy nuclear collisions attributing them to intrinsic fluctuations of temperature of the hadronizing system formed in such processes. To account for these fluctuations we replace the usual Boltzmann-Gibbs (BG) statistics by the non-extensive Tsallis statistics characterized by the nonextensivity parameter q, with |q-1| being a direct measure of fluctuations. In the limit of vanishing fluctuations, q --> 1 and Tsallis statistics converges to the usual BG. We evaluate the nonextensivity parameter q and its dependence on the hadronizing system size from the experimentally observed collision centrality dependence of the mean multiplicity, , and its variance, Var(N). We attribute the observed system size dependence of q to the finiteness of the hadronizing source with q = 1 corresponding to an infinite, thermalized source with a fixed temperature, and with q > 1 (which is observed) corresponding to a finite source in which both the temperature and energy fluctuate.

hep-ph↗
arXiv2008

New Method of Modelling Dissipative Hydrodynamics

We propose to model the dissipative hydrodynamics used in description of the multiparticle production processes ($d$-hydrodynamics) by a special kind of the perfect nonextensive fluid ($q$-fluid) where $q$ denotes the nonextensivity parameter appearing in the nonextensive Tsallis statistics. The advantage of $q$-hydrodynamics lies in its formal simplicity in comparison to the $d$-hydrodynamics. We argue that parameter $q$ describes summarily (at least to some extent) all dynamical effects behind the viscous behavior of the hadronic fluid.

hep-ph↗
arXiv2008

Nonextensive perfect hydrodynamics - a model of dissipative relativistic hydrodynamics?

We demonstrate that nonextensive perfect relativistic hydrodynamics ($q$-hydrodynamics) can serve as a model of the usual relativistic dissipative hydrodynamics ($d$-hydrodynamics) facilitating therefore considerably its applications. As illustration we show how using $q$-hydrodynamics one gets the $q$-dependent expressions for the dissipative entropy current and the corresponding ratios of the bulk and shear viscosities to entropy density, $ζ/s$ and $η/s$.

hep-ph↗
arXiv2008

Causal dissipative hydrodynamics obtained from the nonextensive/dissipative correspondence

We derive the constitutive equations of causal relativistic dissipative hydrodynamics ($d$-hydrodynamics) from perfect nonextensive hydrodynamics ($q$-hydrodynamics) using the nonextensive/dissipative correspondence (NexDC) proposed by us recently. The $q$-hydrodynamics can be thus regarded as a possible model for the $d$-hydrodynamics facilitating its application to high energy multiparticle production processes. As an example we have shown that applying the NexDC to the perfect 1+1 $q$-hydrodynamics, one obtains a proper time evolution of the bulk pressure and the Reynolds number.

nucl-th↗
arXiv2008

Power laws in elementary and heavy-ion collisions - A story of fluctuations and nonextensivity?

We review from the point of view of nonextensive statistics the ubiquitous presence in elementary and heavy-ion collisions of power-law distributions. Special emphasis is placed on the conjecture that this is just a reflection of some intrinsic fluctuations existing in the hadronic systems considered. These systems summarily described by a single parameter q playing the role of a nonextensivity measure in the nonextensive statistical models based on Tsallis entropy.

hep-ph↗
arXiv2008

Dissipative or just Nonextensive hydrodynamics? - Nonextensive/Dissipative correspondence -

We argue that there is correspondence between the perfect nonextensive hydrodynamics and the usual dissipative hydrodynamics, which we call nonextensive/dissipative correspondence (NexDC). It leads to simple expression for dissipative entropy current and allows for predictions for the ratio of bulk and shear viscosities to entropy density, $ζ/s$ and $η/s$.

nucl-th↗