arXiv subjects

K. Fialkowski

Publications and source records attributed to K. Fialkowski.

At least 19 recordsLinked to original sources

arXiv2012

On multiplicity correlations in the STAR data

The STAR data on the multiplicity correlations between narrow psudorapidity bins in the pp and AuAu collisions are discussed. The PYTHIA 8.145 generator is used for the pp data, and a naive superposition model is presented for the AuAu data. It is shown that the PYTHIA generator with default parameter values describes the pp data reasonably well, whereas the superposition model fails to reproduce the centrality dependence seen in the data. Some possible reasons for this failure and a comparison with other models are presented.

nucl-th↗

arXiv2011

Selecting the diffractive events at the LHC energies

The PYTHIA 8 generator is used to estimate the percentage of non-diffractive and diffractive events at the LHC energies. It is shown that a simple condition of the absence of charged hadrons in the central pseudorapidity region is sufficient to remove almost all non-diffractive events. This opens the way to investigate diffraction without waiting for the future specialized detectors.

hep-ph↗

arXiv2011

Note on the CMS multiplicity distributions

The CMS data on the multiplicity distributions are compared with the results from the 8.142 version of the PYTHIA MC event generator with the default tuning and realistic impact parameter profile. The agreement is reasonable. However, it seems to be difficult to improve further this agreement by tuning the parameters determining the multiple parton interactions.

hep-ph↗

arXiv2010

On the multiplicity distributions at LHC energies

The ALICE and CMS data on the multiplicity distributions are compared with the lower energy data and with the results from the 8.142 version of the PYTHIA MC event generator with two tunings. The ALICE data for moments are used to calculate the factorial cumulants. It is suggested that the data on moments or cumulants are well suited to specify the optimal tuning of the model parameters.

hep-ph↗

arXiv2010

Remarks on the particle multiplicities at LHC energies

Recent ALICE data for the multiplicity distributions in the central rapidity bins at LHC energies are compared with the results from two default versions of the PYTHIA 8 generator. We find that, contrary to the earlier versions of PYTHIA, the model overestimates the increase of average multiplicity with energy. Tuning two of the model parameters one obtains reasonable agreement with data. The dependence of the normalized moments of the distribution on the rapidity bin width and on energy is also qualitatively correct.

hep-ph↗

arXiv2010

RHIC multiplicity distributions and superposition models

The recent PHENIX mid-rapidity measurements of multiplicity distributions for centrality bins are analyzed in the framework of superposition models. A simple superposition of pp events is shown to disagree with the heavy ion data for dispersion as a function of centrality. However, it is suggested that a model describing properly the pp data and based in the "wounded quark" idea may be compatible with the multiplicity data for heavy ion collisions.

hep-ph↗

arXiv2010

Superposition models and the multiplicity fluctuations in heavy ion collisions

A class of simple superposition models based on the Glauber picture of multiple collisions is compared with the data on the centrality dependence of the multiplicity distributions in a central rapidity bin. We show how the results depend on the specific assumptions concerning the distributions in the number of participants and their relations to the distributions of the number of produced hadrons in various phase space bins. None of the versions of the model describes satisfactorily the centrality dependence of the scaled dispersion.

hep-ph↗

arXiv2007

On the new HERMES data for the electroproduction on nuclei

We analyze recent data on the electroproduction of hadrons on nuclei using the Lund model for electroproduction on nucleons and a simple geometrical model for the absorption effects. We show that the model seems to overestimate the A-dependence of the absorption effects, although it described the earlier data of the same HERMES experiment reasonably well. We trace the origin of this discrepancy to the surprising difference between the data for nitrogen and neon.

hep-ph↗

arXiv2007

On the electroproduction on nuclei

Recent data on the electroproduction of hadrons on nuclei are discussed. The effects of the nuclear absorption are investigated using the Lund model for electroproduction on nucleons. A simple geometrical model with a minimal number of assumptions and free parameters is shown to describe the data reasonably well.

hep-ph↗

arXiv2007

A remark on the low mass dilepton yield in heavy ion collisions

The recent data on the enhancement of the low mass dilepton yield in heavy ion collisions are interpreted as an effect of the "prolonged life" of resonances in the hadron gas phase. The value of the enhancement factor gives an upper limit for the duration time of this phase.

hep-ph↗

arXiv2005

On the high order multiplicity moments

The description of multiplicity distributions in terms of the ratios of cumulants to factorial moments is analyzed both for data and for the Monte Carlo generated events. For the PYTHIA generated events the moments are investigated for the restricted range of phase-space and for the jets reconstructed from single particle momenta. The results cast doubts on the validity of extended local parton-hadron duality and suggest the possibility of more effective experimental investigations concerning the origin of the observed structure in the dependence of moments on their order.

hep-ph↗

arXiv2004

Tilted plateau in nuclear collisions: data, models and MC-s

The linear dependence of the particle spectra on rapidity is seen in the central region for asymmetric heavy ion collision in the data and in the Monte Carlo results, similarly as in the fragmentation region for hadronic and ion collisions. The origin of such a behaviour is discussed. It is shown that the color string models produce naturally such a shape if string ends are randomly distributed in rapidity.

hep-ph↗

arXiv2002

Parameters in Weight Calculations for the BE Effect

The weight method of implementing the BE effect into Monte Carlo generators is discussed and presented in some detail. We show how the choice of free parameters and the definition of "direct" pions influence the results for the hadronic Z0 decays.

hep-ph↗

arXiv2001

Asymmetric Bose-Einstein effect

Recent results on modelling Bose-Einstein effect in Monte Carlo generators for a source with no spherical symmetry (as seen in the data on $Z^0$ hadronic decays) are reported. Modifications of the weight method necessary for $W^+W^-$ decays are presented and some preliminary results concerning the "inter-$W$" interference effects are discussed.

hep-ph↗

arXiv2001

Charge fluctuations in a final state with QGP

Charge fluctuations as a possible signal of quark - gluon plasma (QGP) were recently suggested. A short summary of comments presented on this subject is given and supplemented by a discussion of the coexistence of pions produced "directly" and through a QGP phase. Such a coexistence may obscure the expected plasma signal similarly to the effects considered in the comments mentioned above.

hep-ph↗

arXiv2001

Correlations and fluctuations - Introduction

A rewiew of the development of formalism to describe correlations and fluctuations in multiparticle production is presented. The milestones of history of this development and some obvious sources of correlations in experimental data are recalled. Some recent subjects concerning the correlations are shortly discussed.

hep-ph↗

arXiv2000

Bose-Einstein effect from asymmetric sources in Monte Carlo generators

We discuss the implementations of the Bose-Einstein effect from asymmetric sources in Monte Carlo generators. A comparison of LEP data with results from the PYTHIA/JETSET code with the standard procedure imitating the effect and with the results from the weight method (with weights depending in various ways on components of momenta differences) is presented. We show that in this last method one can reproduce the experimental hierarchy of the source radii.

hep-ph↗

arXiv2000

Entropy in hadron-hadron collisions

We analyse the entropy properties in the proton-proton 1800 GeV events from the PYTHIA/JETSET Monte Carlo generator following a recent proposal concerning the measurement of entropy in multiparticle systems. The dependence on the number of bins and on the size of the phase-space region is investigated. Our results may serve as a reference sample for experimental data from hadron-hadron and heavy ion collisions.

hep-ph↗