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Maciej Rybczynski

Publications and source records attributed to Maciej Rybczynski.

At least 19 recordsLinked to original sources
arXiv2026

Isospin-symmetry violation -- kaons and beyond (ISO-BREAK 25: summary and outlook)

This report summarizes the presentations and discussions during the ISO-BREAK 25 Workshop ``Isospin symmetry violation: kaons and beyond'', which was held at Jan Kochanowski University in Kielce on October 23-25, 2025. We address the current status of the isospin-symmetry breaking discovered by NA61/SHINE in nucleus-nucleus collisions at the CERN SPS, its confirmation by other experiments and studies in \ee and deep inelastic scattering. In addition, we discuss the theoretical status as well as we outline experimental and theoretical priorities towards understanding this currently unexplained phenomenon.

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arXiv2025

Scaling for count-in-cell and factorial moment analysis

The investigation of remnants associated with the QCD chiral critical point is a primary objective in high-energy ion collision experiments. Numerous studies indicate that a scaling relation between higher-order factorial moments of hadron multiplicity distributions and the second factorial moment may serve as a diagnostic tool for identifying the QCD critical point. However, we demonstrate that this scaling behavior is not exclusive to critical phenomena but rather arises as a general consequence of the phase-space partitioning procedure employed in the analysis. This finding is examined in the context of recent intermittency analyses conducted by the STAR experiment at RHIC.

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arXiv2024

Collective behaviour in proton number fluctuations seen in $\sqrt{s_{NN}}=$ 2.4 GeV Au+Au collisions

At energies of a few GeV per nucleon, nuclear collisions exhibit phenomena more complex than the individualistic nucleon interactions observed at much higher energies. From recent results on proton number fluctuations in Au + Au collisions at $\sqrt{s_{NN}}=2.4$~GeV obtained by the HADES experiment at GSI, we suggest that measuring the multiplicity distributions heavy-ion collisions can be used to probe density fluctuations associated with correlation phenomena. By using the combinant analysis, one can obtain new information contained in them and otherwise unavailable, which may broaden our knowledge of the particle interactions mechanism.

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arXiv2024

Probing multi-particle bunching from intermittency analysis in relativistic heavy-ion collisions

It has been demonstrated that factorial moments analysis in dependence from the size of phase-space cells (when the latter is decreased but is still considerably large), exhibits sensitivity to particle bunching within a system situated in the two-dimensional cell. Based on recent findings concerning fluctuations in charge particle density observed in central Au + Au collisions at various energies ranging from $\sqrt{s_{NN}}$ = 7.7 to 200 GeV at RHIC/STAR, it is proposed that analyzing factorial moments in relativistic heavy-ion collisions could serve as a method to investigate density fluctuations linked to correlation phenomena. Our understanding of particle production mechanisms may be enriched by using factorial moments analysis to gain new information contained in them that was previously unavailable.

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arXiv2023

A Monte Carlo study of multiplicity fluctuations in proton-proton collisions at $\sqrt{s}=$~7~TeV

With large volumes of data available at LHC, it has possible to study the multiplicity distributions. It is interesting as well to check how well event generators can describes the properties and the behavior of multi-particle production processes. In this paper, we analyse the oscillatory behavior of modified combinants in proton-proton collisions at centre of mass energy of 7 TeV.

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arXiv2022

Sub-Poissonian multiplicity distributions in jets produced in hadron collisions

In this work we show that the proper analysis and interpretation of the experimental data on the multiplicity distributions of charged particles produced in jets measured in the ATLAS experiment at the LHC indicates their sub-Poissonian nature. We also show how, by using the recurrent relations and combinants of these distributions, one can obtain new information contained in them and otherwise unavailable, which may broaden our knowledge of the particle production mechanism.

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arXiv2021

Relaxation and correlation times of nonequilibrium multiparticle systems

Relaxation and correlation times are two parameters used frequently in approximate descriptions of the time development of hadronizing system from some initial state towards distributions observed experimentally. Chosen to reproduce the experimental results they represent, in a sense, the history of the hadronization process. The analysis of their changes with energy is the subject of our work.

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arXiv2019

GLISSANDO 3: GLauber Initial-State Simulation AND mOre..., ver. 3

We present ver. 3 of GLISSANDO, a versatile Monte-Carlo generator for Glauber-like models of the initial stages of ultra-relativistic heavy-ion collisions. The present version incorporates the wounded quark model, which is phenomenologically successful in reproducing multiplicities of particle production at RHIC and the LHC. Within this model, one can study the nucleon substructure fluctuation effects, recently explored in p-A collisions. In addition, the code includes the possibility of investigating collisions of light nuclei, such as $^{3}$He and $^{3}$H, or the $α$-clustered $^{7,9}$Be, $^{12}$C, and $^{16}$O, where the deformation of the intrinsic wave function influences the transverse shape of the initial state. The current version, being down-compatible, retains the functionality of the previous releases, such as incorporation of various variants of Glauber-like models, a smooth $NN$ inelasticity profile in the impact parameter obtained from a parametrization of experimental data, fluctuating strength of the entropy deposition, or realistic nuclear distributions of heavy nuclei with deformation. The code can provide output in the format containing the event-by-event source location, which may be further used in modeling the intermediate evolution phase, e.g., with hydrodynamics or transport models. The interface is simplified, such that in the control input file the user may supply only the very basic information, such as the collision energy, the mass numbers of the colliding nuclei, and the model type. GLISSANDO 3 is integrated with the CERN ROOT platform. The package includes numerous illustrative and useful ROOT scripts to compute and plot various results.

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arXiv2019

Multiplicity fluctuations in the Glauber Monte Carlo approach

We discuss multiplicity fluctuations of charged particles produced in nuclear collisions measured event-by-event by the NA49 experiment at CERN SPS within the Glauber Monte Carlo approach. We use the concepts of wounded nucleons and wounded quarks in the mechanism of multiparticle production to characterize multiplicity fluctuations expressed by the scaled variance of multiplicity distribution. Although Wounded Nucleon Model correctly reproduce the centrality dependence of the average multiplicity in Pb+Pb collisions, it completely fails in description of corresponding centrality dependence of scaled variance of multiplicity distribution. Using subnucleonic degrees of freedom, i.e. wounded quarks within Wounded Quark Model, it is possible to describe quite well the multiplicity distribution of charged particles produced in proton+proton interactions. However, the Wounded Quark Model with parameters describing multiplicity distribution of particles produced in proton+proton interactions substantially exceeds the average multiplicity of charged particles produced in Pb+Pb collisions. To obtain values of average multiplicities close to those experimentally measured in Pb+Pb collisions, the concept of shadowed quark sources is implemented. Wounded Quark Model with implemented shadowing source scenario reproduces the centrality dependence of scaled variance of multiplicity distribution of charged particles produced in Pb+Pb collisions in the range from the most central to mid-peripheral interactions.

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arXiv2019

Fluctuations and clustering of multiplicity in collisions of relativistic ions

We discuss the recently measured event-by-event multiplicity fluctuations in relativistic heavy-ion collisions. It is shown that the observed non-monotonic behaviour of the scaled variance of multiplicity distribution as a function of collision centrality (such effect is not observed in a widely used string-hadronic models of nuclear collisions) can be fully explained by the correlations between produced particles promoting cluster formation. We define a cluster as a quasi-neutral gas of charged and neutral particles which exhibits collective behaviour. The characteristic space scale of this shielding is the Debye length. Multiplicity distribution in a cluster is given by Negative Binomial distribution while the rest (reservoir), treated as a superposition of elementary collisions, is described by Binomial distribution. The ability to generate spatial structures (cluster phase) sign the propensity to self-organize of hadronic matter.

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arXiv2019

The Puzzle of Muons in Extensive Air Showers

In order to examine a muon excess observed by the Pierre Auger Observatory, detailed Monte Carlo simulations were carried out for primary protons, iron nuclei and strangelets (hypothetical stable lumps of strange quark matter). We obtained a rough agreement between the simulations and the data for ordinary nuclei without any contribution of strangelets in primary flux of cosmic rays. Our simulations suggest that the shower observables are dominated by details of hadronic interaction models.

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arXiv2016

Wounded quarks at the LHC

We review the results of the wounded quark model, with a stress on eccentricity observables in small systems. A new element is a presentation of symmetric cumulants for the elliptic and triangular flow correlations, obtained in the wounded-quark approach.

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arXiv2016

On wounded constituents in nuclear collisions

In this talk we summarize the main results of our recent paper, Phys. Rev. C94, 014902, where we explore predictions of the wounded quark model for particle production and the properties of the initial state formed in ultra-relativistic collisions of atomic nuclei.

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arXiv2016

Muon bundles from extensive air showers

In this talk we present a possible explanation of the presence of high muon multiplicity events registered recenty by CERN ALICE experiment in its dedicated cosmic ray run.

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arXiv2016

Wounded quarks in A+A, p+A, and p+p collisions

We explore predictions of the wounded quark model for particle production and properties of the initial state formed in ultrarelativistic heavy-ion collisions. The approach is applied uniformly to A+A collisions in a wide collision energy range, as well as for p+A and p+p collisions at the CERN Large Hadron Collider (LHC). We find that generically the predictions from wounded quarks for such features as eccentricities or initial sizes are close (within 15\%) to predictions of the wounded nucleon model with an amended binary component. A larger difference is found for the size in p+Pb system, where the wounded quark model yields a smaller (more compact) initial fireball than the standard wounded nucleon model. The inclusion of subnucleonic degrees of freedom allows us to analyze p+p collisions in an analogous way, with predictions that can be used in further collective evolution. The approximate linear dependence of particle production in A+A collisions on the number of wounded quarks, as found in previous studies, makes the approach based on wounded quarks natural. Importantly, at the LHC energies we find approximate uniformity in particle production from wounded quarks, where at a given collision energy per nucleon pair similar production of initial entropy per source is needed to explain the particle production from p+p collisions up to A+A collisions. We also discuss the sensitivity of the wounded quark model predictions to distribution of quarks in nucleons, distribution of nucleons in nuclei, and to the quark-quark inelasticity profile in the impact parameter. In our procedure, the quark-quark inelasticity profile is chosen in such a way that the experiment-based parametrization of the proton-proton inelasticity profile is properly reproduced. The parameters of the overlaid multiplicity distribution is fixed from p+p and p+Pb data.

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arXiv2015

Fluctuations of flow harmonics in Pb+Pb collisions at $\sqrt{s_{NN}}=2.76$~TeV from the Glauber model

In the framework of the Glauber model as implemented in GLISSANDO 2, we study the fluctuations of flow harmonics in Pb+Pb collisions at the LHC centre-of-mass energy of 2.76 TeV. The model with wounded nucleons and the admixture of binary collisions leads to reasonable agreement for the ellipticity and triangularity fluctuations with the experimental data from the ATLAS, ALICE, and CMS collaborations, verifying the assumption that the initial eccentricity is approximately proportional to the harmonic flow of charged particles. While the agreement, in particular at the level of event-by-event distributions of eccentricities/flow coefficients in not perfect, it leads to a fair (at the level of a few percent for all centralities except the most peripheral collisions) description of the scaled standard deviation and the F measure which involve the four-particle cumulants. We also discuss the case of quadrangular flow. Computer scripts that generate our results from the GLISSANDO 2 simulations are provided.

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arXiv2014

System size dependence of the log-periodic oscillations of transverse momentum spectra

Recently the inclusive transverse momentum distributions of primary charged particles were measured for different centralities in $Pb+Pb$ collisions. A strong suppression of the nuclear modification factor in central collisions around $p_T \sim 6-7$ GeV/c was seen. As a possible explanation, the hydrodynamic description of the collision process was tentatively proposed. However, such effect, (albeit much weaker) also exists in the ratio of data/fits, both in nuclear $Pb+Pb$ collisions, and in the elementary $p+p$ data in the same range of transverse momenta for which such an explanation is doubtful. As shown recently, in this case, assuming that this effect is genuine, it can be attributed to a specific modification of a quasi-power like formula usually used to describe such $p_T$ data, namely the Tsallis distribution. Following examples from other branches of physics, one simply has to allow for the power index becoming a complex number. This results in specific log-periodic oscillations dressing the usual power-like distribution, which can fit the $p+p$ data. In this presentation we demonstrate that this method can also describe $Pb+Pb$ data for different centralities. We compare it also with a two component statistical model with two Tsallis distributions recently proposed showing that data at still larger $p_T$ will be sufficient to discriminate between these two approaches.

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