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Katarzyna Grebieszkow

Publications and source records attributed to Katarzyna Grebieszkow.

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

News from NA61/SHINE

The main goal of the NA61/SHINE strong interaction program is to search for the critical point in the phase diagram of strongly interacting matter and to investigate phenomena related to the onset of deconfinement. In recent years, the program has expanded to include the study of open charm, aiming to understand the mechanisms of its production in heavy-ion collisions. This article presents a selection of recent results from the NA61/SHINE strong interaction program, including findings on particle spectra and yields, as well as fluctuations and correlations. Plans for the near future are also discussed.

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arXiv2019

New results on spectra and fluctuations from NA61/SHINE

The NA61/SHINE experiment aims to discover the critical point of strongly interacting matter and study the properties of the onset of deconfinement. For this purpose we perform a two-dimensional scan of the ($T-μ_{B}$) phase diagram by varying the energy ($5.1 < \sqrt{s_{NN}} < 16.8/17.3$ GeV) and the system size (p+p, p+Pb, Be+Be, Ar+Sc, Xe+La, Pb+Pb) of the collisions. In this article the NA61/SHINE results on particle spectra as well as fluctuations and correlations in p+p, Be+Be, Ar+Sc, and Pb+Pb collisions are presented. In particular, the latest results on charged kaons spectra, charged pions ratios (electromagnetic effects), proton intermittency, and anisotropic flow are discussed. Finally, the motivation, NA61/SHINE plans, and the first measurements of open charm production in heavy ion collisions at the Super Proton Synchrotron energies are shown.

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arXiv2018

Event-by-event fluctuations in p+p and central A+A collisions within relativistic transport models

Event-by-event multiplicity fluctuations in nucleus-nucleus collisions are studied within the relativistic transport models: EPOS, PHSD, and UrQMD. As measures of particle number fluctuations we consider the scaled variances $ω[X]$ for positive, negative, and all charged hadrons, and the strongly intensive quantities $Δ[K^+,π^+],$ $Σ[K^+,π^+]$ for $K^+$ and $π^+$ yields. At the SPS energy range the fluctuation measures are calculated for proton-proton, Ar+Sc, and Pb+Pb collisions. Comparison with recent NA61/SHINE and older NA49 measurements of the multiplicity fluctuations is done. A validity of the model of independent sources, a role of the experimental acceptance, and the centrality selection procedure are studied.Event-by-event multiplicity fluctuations in nucleus-nucleus collisions are studied within the relativistic transport models: EPOS, PHSD, and UrQMD. As measures of particle number fluctuations we consider the scaled variances $ω[X]$ for positive, negative, and all charged hadrons, and the strongly intensive quantities $Δ[K^+,π^+],$ $Σ[K^+,π^+]$ for $K^+$ and $π^+$ yields. At the SPS energy range the fluctuation measures are calculated for proton-proton, Ar+Sc, and Pb+Pb collisions. Comparison with recent NA61/SHINE and older NA49 measurements of the multiplicity fluctuations is done. A validity of the model of independent sources, a role of the experimental acceptance, and the centrality selection procedure are studied.

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arXiv2017

New results on fluctuations and correlations from the NA61/SHINE experiment at the CERN SPS

The exploration of the QCD phase diagram is the most important task of present heavy ion experiments. In particular, we want to study the phase transition from hadronic to partonic matter and look for the critical point (CP) of strongly interacting matter. Fluctuations and correlations in kinematic characteristics and particle yields may help to locate the CP (in analogy to enlarged fluctuations due to critical opalescence close to a CP in a liquid/gas transition). The strong interactions program of the NA61/SHINE experiment may allow to discover or rule out the existence of the CP in the Super Proton Synchrotron energy domain. For this purpose we perform a two-dimensional scan by varying the energy ($5.1 < \sqrt{s_{NN}} < 16.8/17.3$ GeV) and the system size (p+p, p+Pb, Be+Be, Ar+Sc, Xe+La, Pb+Pb) of the collisions. In this report new NA61/SHINE results on fluctuations and correlations in p+p, Be+Be, and Ar+Sc collisions are presented. In particular, results on transverse momentum and multiplicity fluctuations, as well as higher order moments of net-charge fluctuations are discussed. The NA61/SHINE data are compared to predictions of string hadronic models and to NA49 results.

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arXiv2017

News from strong interactions program of the NA61/SHINE experiment

The NA61/SHINE experiment aims to discover the critical point of strongly interacting matter and study the properties of the onset of deconfinement. This is performed by a two dimensional phase diagram ($T-μ_B$) scan of measurements of particle spectra and fluctuations in proton-proton, proton-nucleus and nucleus-nucleus interactions as a function of collision energy and system size. In this contribution new NA61/SHINE results on negative pion production, as well as transverse momentum and multiplicity fluctuations in Ar+Sc collisions are presented. Moreover, the latest results on higher order moments of net-charge multiplicity distribution in p+p collisions are also discussed. The Ar+Sc results are compared to NA61 p+p and Be+Be data, as well as to NA49 $A+A$ results.

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arXiv2015

Strongly Intensive Measures for Particle Number Fluctuations: Effects of Hadronic Resonances

Strongly intensive measures $Δ$ and $Σ$ are used to study event-by-event fluctuations of hadron multiplicities in nucleus-nucleus collisions. The effects of resonance decays are investigated within statistical model and relativistic transport model. Two specific examples are considered: resonance decays to two positively charged particles (e.g., $Δ^{++}\rightarrow p+ π^+$) and to $π^+π^-$-pairs. (e.g., $ρ^0\rightarrow π^-+π^+$). It is shown that resonance abundances at the chemical freeze-out can be estimated by measuring the fluctuations of the number of stable hadrons. These model results are compared to the full hadron-resonance gas analysis within both the grand canonical and canonical ensemble. The ultra-relativistic quantum molecular dynamics (UrQMD) model of nucleus-nucleus collisions is used to illustrate the role of global charge conservation, centrality selection, and limited experimental acceptance.

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arXiv2014

Hot strong matter

The recent results on relativistic heavy-ion collisions are discussed. The most convincing quark-gluon plasma signatures at the LHC and the top RHIC energies are presented. Moreover, the possible methods of evaluating the energy threshold for deconfinement (onset of deconfinement) are described, and the corresponding results from the RHIC Beam Energy Scan and the SPS programs are shown. Additionally, the first signatures of creating dense and collectively behaving systems in collisions of small nuclei (or even in elementary interactions) are discussed. Finally, the current status of experimental search for the critical point of strongly interacting matter is summarized.

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arXiv2014

Strongly Intensive Measures for Transverse Momentum and Particle Number Fluctuations

The strongly intensive measures $Δ[P_T,N]$ and $Σ[P_T,N]$ are used to study the event-by-event fluctuations of the transverse momentum $P_T$ and particle multiplicity $N$ in nucleus-nucleus collisions. A special normalization for these fluctuation measures ensures that they are dimensionless and yields a common scale required for a quantitative comparison of fluctuations. In this paper basic properties of the $Δ[P_T, N]$ and $Σ[P_T, N]$ measures are tested within different phenomenological models using the Monte Carlo simulations (the so-called fast generators) and analytical solutions. The obtained results are helpful to elucidate the properties of $Δ[P_T,N]$ and $Σ[P_T,N]$ measures.

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arXiv2012

Testing new strongly intensive measures of transverse momentum fluctuations

Recently, the new strongly intensive measures of fluctuations $Δ$ and $Σ$ have been proposed. In this publication their properties are tested using an example of event-by-event transverse momentum fluctuations. The obtained values are compared to the long used $Φ$ measure of pT fluctuations. Several tests are preformed within data produced by fast generators, as well as by the UrQMD model. The UrQMD calculations are presented for the systems and energies which are planned to be studied in the NA61/SHINE experiment at the CERN Super Proton Synchrotron.

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arXiv2012

Status and plans of the ion program of NA61 at the CERN SPS

The NA61/SHINE at the CERN SPS is a new experiment to study hadron production in p+p p+A, h+A and A+A interactions. The main goal of the NA61 ion program is to explore the phase diagram (T - mu_B) of strongly interacting matter. In particular, we plan to study the properties of the onset of deconfinement and to search for the signatures of the critical point. A two-dimensional scan of the phase diagram will be performed by varying the energy (13A-158A GeV) and system size (p+p, Be+Be, Ar+Ca, Xe+La) of collisions. This paper summarizes the status and plans of the NA61/SHINE ion program. In particular the detector upgrades, data taking schedule and the first results on spectra and correlations are discussed.

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arXiv2011

Report from NA49

The signatures of the onset of deconfinement, found by the NA49 experiment at low SPS energies, are confronted with new results from the Beam Energy Scan (BES) program at BNL RHIC and CERN LHC results. Additionally, new NA49 results on chemical (particle ratio) fluctuations, azimuthal angle fluctuations, intermittency of di-pions, etc. are presented.

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arXiv2011

Deciphering Azimuthal Correlations in Relativistic Heavy-Ion Collisions

We discuss various sources of azimuthal correlations in relativistic heavy-ion collisions. The integral measure Phi is applied to quantify the correlations. We first consider separately the correlations caused by the elliptic flow, resonance decays, jets and transverse momentum conservation. An effect of randomly lost particles is also discussed. Using the PYTHIA and HIJING event generators we produce a sample of events which mimic experimental data. By means of kinematic cuts and particle's selection criteria, the data are analyzed to identify a dominant source of correlations.

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arXiv2011

Methods to study event-by-event fluctuations in the NA61/SHINE experiment at the CERN SPS

Theoretical calculations locate the critical point of strongly interacting matter (CP) at energies accessible at the CERN SPS. Event-by-event transverse momentum and multiplicity fluctuations are considered as one of the most important tools to search for the CP. Pilot studies of the energy dependence and the system size dependence of both $p_T$ and multiplicity fluctuations were performed by the NA49 experiment. The NA61/SHINE ion program is a continuation of these efforts. After briefly recalling the essential NA49 results on fluctuations we will discuss the technical methods (removing Non-Target interactions) which we plan to apply for future transverse momentum and multiplicity fluctuation analyses.

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arXiv2010

Fluctuations of the azimuthal particle distribution in NA49 at the CERN SPS

Event-by-event fluctuations and correlations in azimuthal angle are currently widely investigated in various experiments. In this paper the $Φ$ measure (earlier used in experiments to evaluate fluctuations in transverse momentum) is now applied to azimuthal angle $ϕ$. Properties of this $Φ_ϕ$ function are investigated through fast generators and with complex models such as Pythia, Hijing, and UrQMD. Preliminary results of NA49 on $Φ_ϕ$ are also presented. The system size dependence (p+p, C+C, Si+Si and 6 centralities of Pb+Pb) at the highest SPS energy (158$A$ GeV) is shown, as well as the energy dependence (20$A$ - 158$A$ GeV) for the 7.2\% most central Pb+Pb interactions.

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arXiv2010

NA49 and NA61/SHINE experiments: results and perspectives

The Super Proton Synchrotron (SPS) covers one of the most interesting regions of the QCD phase diagram $(T - μ_B)$. On the one hand there are indications that the energy threshold for deconfinement is reached already at low SPS energies. On the other hand theoretical calculations locate the QCD critical end-point at energies accessible at the SPS. In this paper the NA49 signatures of the onset of deconfinement are presented. Results are shown on pion production, the kaon to pion ratio, slopes of transverse mass spectra ("temperature"), and event-by-event particle ratio fluctuations versus collision energy, for central $Pb+Pb$ interactions. Next we show possible indications of the critical point in event-by-event mean transverse momentum and multiplicity fluctuations. Finally we discuss the future ion program of the NA61/SHINE experiment (energy scan with light ions).

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arXiv2009

Search for the critical point of strongly interacting matter in NA49

Theoretical calculations locate the QCD critical point at energies accessible at the CERN SPS. Several observables were suggested to look for it. Here, we present the system size dependence and the energy dependence of event-by-event mean transverse momentum and multiplicity fluctuations, as well as the energy dependence of anti-baryon to baryon ratios.

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