arXiv subjects

G. Wilk

Publications and source records attributed to G. Wilk.

At least 19 recordsLinked to original sources

arXiv2025

Nuclear modification factor within a dynamical approach to the complex entropic index

This work introduces a novel approach to the nuclear deformation factor $R_{\text{AA}}$, grounded in the dynamical effects of the Quark-Gluon Plasma on parton momentum. The approach uses the Blast-Wave method combined with Tsallis Statistics, within the Cooper-Frye freeze-out framework and, by profiting from appropriate simplifications, it gives analytical expressions that describe the observed $R_{\text{AA}}$ for two sets of independent measurements at $\sqrt{s}=2.76$ TeV and $\sqrt{s}=5.02$ TeV. A nonlinear dynamical equation describes the dynamics and leads to log-periodic oscillations. With the analytical solutions for that equation, it is possible to link the dynamical approach with the complex-$q$ formalism, which was proposed to describe the log-oscillations observed in experimental data.

hep-ph↗

arXiv2024

Emergence of KNO scaling in multiplicity distributions in jets produced at the LHC

In this work we study the multiplicity distributions (MDs) of charged particles within jets in proton-proton collisions, which were measured by the ATLAS collaboration in 2011, 2016 and 2019. The first data set refers to jets with lower transverse momenta ($4 < p_T < 40$ GeV ) whereas the other two refer to higher $p_T$ jets ($0.1 < p_T < 2.5$ TeV). We find that the first set shows no sign of KNO scaling whereas the higher $p_T$ sets gradually approach the scaling limit. In the first set the mean multiplicity as a function of $p_T$ can be well described by expressions derived from QCD with different approximation schemes. For higher ($> 500$ GeV) values of $p_T$ these expressions significantly overshoot the data. We show that the behavior of the MDs can be well represented by a Sub-Poisson distribution with energy dependent parameters. In the range $40 < p_T < 100$ GeV there is a transition from sub to super poissonian behavior and the MD evolves to a geometric distribution, which shows KNO scaling. In this way we fit the MDs in all transverse momentum intervals with one single expression. We discuss the implications of this phenomenological finding.

hep-ph↗

arXiv2020

A look at multiparticle production via modified combinants

As shown recently, one can obtain additional information from the measured charged particle multiplicity distributions, $P(N)$, by investigating the so-called modified combinants, $C_j$, extracted from them. This information is encoded in the observed specific oscillatory behaviour of $C_j$, which phenomenologically can be described only by some combinations of compound distributions based on the Binomial Distribution. So far this idea has been checked in $pp$ and $e^+e^-$ processes (where observed oscillations are spectacularly strong). In this paper, we continue observation of multiparticle production from the modified combinants perspective by investigating dependencies of the observed oscillatory patterns on type of colliding particles, their energies and the phase space where they are observed. We also offer some tentative explanations based on different types of compound distributions and stochastic branching processes.

hep-ph↗

arXiv2019

Modified combinant analysis of the $e^+e^-$ multiplicity distributions

As shown recently, one can obtain additional information from the measured multiplicity distributions, $P(N)$, by extracting the so-called modified combinants, $C_j$. This information is encoded in their specific oscillatory behavior, which can be described only by some combinations of compound distributions, the basic part of which is the Binomial Distribution. So far this idea was applied to $pp$ and $p\bar{p}$ processes; in this note we show that an even stronger effect is observed in the $C_j$ deduced from $e^+e^-$ collisions. We present its possible explanation in terms of the so called Generalised Multiplicity Distribution (GMD) proposed some time ago.

hep-ph↗

arXiv2019

A look at multiplicity distributions via modified combinants

The experimentally measured multiplicity distributions exhibit, after closer inspection, peculiarly enhanced void probability and oscillatory behavior of the modified combinants. We show that both these features can be used as additional sources of information, not yet fully explored, on the mechanism of multiparticle production. We provide their theoretical understanding within the class of compound distributions.

hep-ph↗

arXiv2019

An example of the interplay of nonextensivity and dynamics in the description of QCD matter

Using a simple quasi-particle model of QCD matter, presented some time ago in the literature, in which interactions are modelled by some effective fugacities z, we investigate the interplay between the dynamical content of fugacities z and effects induced by nonextensivity in situations when this model is used in a nonextensive environment characterized by some nonextensive parameter q $\neq$ 1 (for the usual extensive case q=1). This allows for a better understanding of the role of nonextensivity in the more complicated descriptions of dense hadronic and QCD matter recently presented (in which dynamics is defined by a lagrangian, the form of which is specific to a given model).

hep-ph↗

arXiv2018

Intriguing feature of multiplicity distributions

Multiplicity distributions, P(N), provide valuable information on the mechanism of the production process. We argue that the observed P(N) contain more information (located in the small N region) than expected and used so far. We demonstrate that it can be retrieved by analysing specific combinations of the experimentally measured values of P(N) which we call {it modified combinants, Cj, and which show distinct oscillatory behavior, not observed in the usual phenomenological forms of the P(N) used to fit data. We discuss the possible sources of these oscillations and their impact on our understanding of the multiparticle production mechanism.

hep-ph↗

arXiv2017

Muon bundles from the Universe

Recently the CERN ALICE experiment, in its dedicated cosmic ray run, observed muon bundles of very high multiplicities, thereby confirming similar findings from the LEP era at CERN (in the CosmoLEP project). Significant evidence for anisotropy of arrival directions of the observed high multiplicity muonic bundles is found. Estimated directionality suggests their possible extragalactic provenance. We argue that muonic bundles of highest multiplicity are produced by strangelets, hypothetical stable lumps of strange quark matter infiltrating our Universe.

hep-ph↗

arXiv2017

Muon bundles as a sign of strangelets from the Universe

Recently the CERN ALICE experiment, in its dedicated cosmic ray run, observed muon bundles of very high multiplicities, thereby confirming similar findings from the LEP era at CERN (in the CosmoLEP project). Originally it was argued that they apparently stem from the primary cosmic rays with a heavy masses. We propose an alternative possibility arguing that muonic bundles of highest multiplicity are produced by strangelets, hypothetical stable lumps of strange quark matter infiltrating our Universe. We also address the possibility of additionally deducing their directionality which could be of astrophysical interest. Significant evidence for anisotropy of arrival directions of the observed high multiplicity muonic bundles is found. Estimated directionality suggests their possible extragalactic provenance.

hep-ph↗

arXiv2014

Tsallis distribution with complex nonextensivity parameter q

We discuss a Tsallis distribution with complex nonextensivity parameter $q$. In this case the usual distribution is decorated with a log-periodic oscillating factor (apparently, such oscillations can bee seen in recently measured transverse momentum distributions in collisions at very high energies). Complex $q$ also means complex heat capacity which shall also be briefly discussed.

cond-mat.stat-mech↗

arXiv2012

Scaling behavior of transverse momenta distributions in hadronic and nuclear collisions

It has been recently noticed that transverse momenta ($p_T$) distributions observed in high energy production processes exhibit remarkably universal scaling behavior. This is seen when they are in some suitable variable, replacing the usual $p_T$. On the other hand, it is also known that transverse momenta distributions in general follow a power-like Tsallis distribution, rather than an exponential Boltzmann-Gibbs, with a (generally energy dependent) nonextensivity parameter $q$. We now show that it is possible to choose a suitable variable such that $p_T$ distributions of particles produced in proton-proton interactions in a wide energy range can be fitted by the same Tsallis distribution (with the same, energy independent, value of the $q$-parameter). Similar scaling behavior in nucleus-nucleus collisions is also observed. The possible dynamical origin of the q parameter used in these fits will be discussed.

hep-ph↗

arXiv2011

Nonextensive critical effects in relativistic nuclear mean field models

We present a possible extension of the usual relativistic nuclear mean field models widely used to describe nuclear matter towards accounting for the influence of possible intrinsic fluctuations caused by the environment. Rather than individually identifying their particular causes we concentrate on the fact that such effects can be summarily incorporated in the changing of the statistical background used, from the usual (extensive) Boltzman-Gibbs one to the nonextensive taken in the form proposed by Tsallis with a dimensionless nonextensivity parameter $q$ responsible for the above mentioned effects (for $q \rightarrow 1$ one recovers the usual BG case). We illustrate this proposition on the example of the QCD-based Nambu - Jona-Lasinio (NJL) model of a many-body field theory describing the behavior of strongly interacting matter presenting its nonextensive version. We check the sensitivity of the usual NJL model to a departure from the BG scenario expressed by the value of $| q - 1|$, in particular in the vicinity of critical points.

nucl-th↗

arXiv2009

Nonextensive effects in the Nambu--Jona-Lasinio model of QCD

We present a nonextensive version of the recently discussed QCD-based Nambu - Jona-Lasinio (NJL) model of many-body field theory describing behavior of strongly interacting matter. It is based on the nonextensive generalization of the Boltzmann-Gibbs (BG) statistical mechanics used in NJL model, which was taken in the form proposed by Tsallis and characterized by a dimensionless nonextensivity parameter q (for q -> 1 one recovers the usual BG case). This is a new phenomenological parameter of the model which accounts summarily for all possible (so far unspecified) effects leading to departure from the conditions required by the usual BG approach to be fully applicable. It turns out that temperature dependencies of chiral symmetry restoration, masses of pion and sigma meson and characteristic features of spinodal decomposition are sensitive to the departures from the usual BG case.

nucl-th↗

arXiv2008

Cosmic rays from thermal sources

Energy spectrum of cosmic rays (CR) exhibits power-like behavior with very characteristic "knee" structure. We consider a generalized statistical model for the production process of cosmic rays which accounts for such behavior in a natural way either by assuming existence of temperature fluctuations in the source of CR, or by assuming specific temperature distribution of CR sources. Both possibilities yield the so called Tsallis statistics and lead to the power-like distribution. We argue that the "knee" structure arises as result of abrupt change of fluctuations in the source of CR. Its possible origin is briefly discussed.

astro-ph↗

arXiv2008

Nonextensive hydrodynamics for relativistic heavy-ion collisions

The nonextensive one-dimensional version of a hydrodynamical model for multiparticle production processes is proposed and discussed. It is based on nonextensive statistics assumed in the form proposed by Tsallis and characterized by a nonextensivity parameter $q$. In this formulation the parameter $q$ characterizes some specific form of local equilibrium which is characteristic for the nonextensive thermodynamics and which replaces the usual local thermal equilibrium assumption of the usual hydrodynamical models. We argue that there is correspondence between the perfect nonextensive hydrodynamics and the usual dissipative hydrodynamics. 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 $η/s$, to be made.

nucl-th↗

arXiv2007

Some forgotten features of the Bose Einstein Correlations

Notwithstanding the visible maturity of the subject of Bose-Einstein Correlations (BEC), as witnessed nowadays, we would like to bring to ones attention two points, which apparently did not received attention they deserve: the problem of the choice of the form of $C_2(Q)$ correlation function when effects of partial coherence of the hadronizing source are to be included and the feasibility to model effects of Bose-Einstein statistics, in particular the BEC, by direct numerical simulations.

hep-ph↗

arXiv2007

Tsallis distribution from minimally selected order statistics

We demonstrate that selection of the minimal value of ordered variables leads in a natural way to its distribution being given by the Tsallis distribution, the same as that resulting from Tsallis nonextensive statistics. The possible application of this result to the multiparticle production processes is indicated.

cond-mat.stat-mech↗

arXiv2006

Fluctuations, correlations and the nonextensivity

Examples of joint probability distributions are studied in terms of Tsallis' nonextensive statistics both for correlated and uncorrelated variables, in particular it is explicitely shown how correlations in the system can make Tsallis entropy additive and that the effective nonextensivity parameter $q_N$ decreases towards unity when the number of variables $N$ increases. We demonstrate that Tsallis distribution of energies of particles in a system leads in natural way to the Negative Binomial multiplicity distribution in this system.

cond-mat.stat-mech↗