arXiv subjects
Publications and source records attributed to G. Wilk.
The nonextensitivity parameter $q$ occuring in some of the applications of Tsallis statistics (known also as index of the corresponding Lévy distribution) is shown to be given, in $q>1$ case, entirely by the fluctuations of the parameters of the usual exponential distribution.
We investigate the effect of nonextensive statistics as applied to the chemical fluctuations in high-energy nuclear collisions discussed recently using the event-by-event analysis of data. It turns out that very minuite nonextensitivity changes drastically the expected experimental output for the fluctuation measure. This results is in agreement with similar studies of nonextensity performed recently for the transverse momentum fluctuations in the same reactions.
We have extended recently proposed model of parton distribution i nucleons to the case of nucleons in nuclei.
Using simple space-time implementation of the random cascade model we investigate numerically influence of the possible fractal structure of the emitting source on Bose-Einstein correlations between identical particles. The results are then discussed in terms of the non-extensive Tsallis statistics.
Using simple space-time implementation of the random cascade model we investigate numerically a conjecture made some time ago which was joining the intermittent behaviour of spectra of emitted particles with the possible fractal structure of the emitting source. We demonstrate that such details are seen, as expected, in the Bose-Einstein correlations between identical particles. \\
We demonstrate on simple examples that oscillatory behaviour of moments of multiplicity distributions P(n) observed in e^+e^- annihilations, in hadronic pp collisions and in collisions on nuclei, p+A, is to a large extend caused by the experimental artifact of measuring only limited range of P(n). In particular we show that by applying a suitable universal cutt-off procedure to the measured P(n) one gets for reactions mentioned before oscillations of similar magnitude. The location of zeros of oscillations as a function of the rank of moments and their shapes remain, however, distinctively different for different types of reactions considered. This applies to some extend also to collisions of nuclei, which otherwise follow their own pattern of behaviour.
We have proposed a new method for the Coulomb wave function correction which includes the momentum resolution for charged hadron pairs and applied it to the precise data on pi^+pi^- correlations obtained in p + Ta reaction at 70 GeV/c. It is found that interaction regions of this reaction (assuming Gaussian source function) are 9.8+-5.8 fm and 7.7+-4.8 fm for the thicknesses of the target 8 micro m and 1.4 micro m, respectively. We have also analyzed the data by the formula including strong interaction effect. The physical picture of the source size obtained in this way is discussed.
The inelasticity of hadron-carbon collisions for energies exceeding 100 TeV is estimated from the carbon-emulsion chamber data at Pamirs to be $ = 0.65\pm 0.08$. When combined with data on hadron-lead collisions taken at the same energy range it results in the $K\sim A^{0.086}$ mass number dependence of inelasticity. The evaluated partial inelasticity for secondary ($ν> 1$) interactions, $K_{ν>1} \simeq 0.2$, suggests that most of the energy is lost in the first interaction.
We argue that the so called long flying component (LFC) observed in some cosmic ray experiments are yet another manifestation of Lévy distributions (with index $q=1.3$), this time of the distribution observation probability of the depths of starting points of cascades. It means that LFC is governed by the so called long-tail Lévy-like anomalous superdiffusion, a phenomenon frequently encountered in Nature. Its connection with the so called Tsallis's statistics is also briefly discussed.
The inelasticity of hadron-carbon nucleus collisions in the energy region exceeding 100 TeV is estimated from the carbon-emulsion chamber data at Pamirs to be $ = 0.65\pm 0.08$. When combined with the recently presented data on hadron-lead nucleus collisions taken at the same energy range it results in the $K\sim A^{0.086}$ mass number dependence of inelasticity. The evaluated partial inelasticity for secondary ($ν> 1$) interactions, $K_{ν>1} \simeq 0.2$, suggests that the second and higher interactions of the excited hadron inside the nucleus proceed with only slight energy losses.
Using a QCD inspired model developed by our group for particle production, the Interacting Gluon Model (IGM), we have made a systematic analysis of all available data on leading particle spectra. These data include diffractive collisions and photoproduction at HERA. With a small number of parameters (essentially only the non-perturbative gluon-gluon cross section and the fraction of diffractive events) good agreement with data is found. We show that the difference between pion and proton leading spectra is due to their different gluon distributions. We predict a universality in the diffractive leading particle spectra in the large momentum region, which turns out to be independent of the incident energy and of the projectile type.
Recent DESY-HERA data on $J/Ψ$ elasticity distribution show that it emerges mostly as a fast particle. Interpreting photoproduction as a collision between a pre-formed charmed hadron and the proton, the outcoming $J/Ψ$ is a leading particle of the collision. We analyse these data using a model formulated to describe energy flow in hadron-hadron reactions. The measured $J/Ψ$ spectrum can be successfully described in terms of this model. We conclude that the observed transparency of the charmed hadron-proton collisions arises because of the particularly small gluonic content of the initial $c - \bar c$ state.
We have applied the Interacting Gluon Model (IGM) to calculate diffractive mass spectra measured recently in e-p collisions at HERA. We show that it is possible to treat them in terms of gluon-gluon collisions in the same way as was done before for hadronic collisions. Analysis of available data is performed.
We are presenting here the new formulae for Bose-Einstein correlations (BEC) which contain effects of final state interactions (FSI) of both strong (in $s$-wave) and electromagnetic origin. We demonstrate the importance of FSI in BEC by analysing data for $e^+e^-$ annihilation and for heavy collisions. The inclusion of FSI results in the practical elimination (at least in $e^+e^-$ data) of the so called degree of coherence parameter $λ$ (which becomes equal unity) and the long range parameter $γ$ (which is now equal zero).
Recently we have found that integral of the squared Coulomb wave function describing systemcomposed of charged pion and central charged fragment $Z_{eff}$ protons, $|ψ_r(r)|^2$, times pion source function $ρ(r)$ (of the size $β$), $\intdr |ψ_r(r)|^2 ρ(r)$, shows a quasiscaling behavior. This is approximately invariant under the following transformation: $(β,Z_{eff}) \to (λβ,λZ_{eff})$; $λ>0$. We called such behavior $β-Z_{eff}$ quasiscaling. We examine this quasiscaling behavior in detail. In particular we provide a semi-analytical examination of this behavior and confirm it for the exponential pionic source functions in addition to the Gaussian ones and for the production of K mesons as well. When combined with the results of the HBT, a result of the yield ratio allows us to estimate the size of the central charged fragment (CCF) to be $125\le Z_{eff}\le 150$ for Pb+Pb collisions at energy 158 GeV/nucleon. From our estimation, the baryon number density $0.024 \le n_{B}\le0.036$ [1/fm^3] is obtained.
We have extended the Interacting Gluon Model (IGM) to calculate diffractive mass spectra generated in hadronic collisions. We show that it is possible to treat both diffractive and non-diffractive events on the same footing, in terms of gluon-gluon collisions. A systematic analysis of available data is performed. The energy dependence of diffractive mass spectra is addressed. They show a moderate narrowing at increasing energies. Predictions for LHC energies are presented.
The requirements for observing Centauro-like phenomena and their role as possible probes of deeply penetrating component in Cosmic Rays are discussed.
We propose model of propagation of lumps of Strange Quark Matter (strangelets) through the atmosphere, which accounts for their apparent strong penetrability and normal nuclear-type sizes at the same time. The mass spectrum of strangelets reaching the Earth predicted by this model agrees very well with the existing data on the abundance of different elemets in the Universe.