Multiparticle production processes from the Information Theory point of view

We look at multiparticle production processes from the Information Theory point of view, both in its extensive and nonextensive versions. Examples of both symmetric (like pp or AA) and asymmetric (like pA) collisions are considered showing that some ways of description of experimental data used in the literature are of more general validity than usually anticipated.}Comment: Talk given at 4th Budapest Winter School On Heavy Ion Physics (2004) 16 pages, 5 figures; version published in APH (HIP

Quantum Clan Model description of Bose Einstein Correlations

We propose a novel numerical method of modelling Bose-Einstein correlations (BEC) observed among identical (bosonic) particles produced in multiparticle production reactions. We argue that the most natural approach is to work directly in the momentum space in which the Bose statistics of secondaries reveals itself in their tendency to bunch in a specific way in the available phase space. Because such procedure is essentially identical to the clan model of multiparticle distributions proposed some time ago, therefore we call it the Quantum Clan Model.Comment: Talk given at 4th Budapest Winter School On Eavy Ion Physics (2004), 6 pages, two figures; version published in APH (HIP

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.Comment: Invited talk presented at XLVIII International Symposium on Multiparticle Dynamics (ISMD2018), 3 to 7 September 2018, Singapore; 10 pages, 6 figures. To be published in EPJ Web of Conference

On the chemical composition of cosmic rays of highest energy

We present arguments aiming at reconciling apparently contradictory results concerning the chemical composition of cosmic rays of highest energy, coming recently from the Auger and HiRes collaborations. In particular, we argue that the energy dependence of the mean value and root mean square fluctuation of shower maxima distributions observed by the Auger experiment are not necessarily caused by the change of nuclear composition of primary cosmic rays. They could also be caused by the change of distribution of the first interaction point in the cascade. A new observable, in which this influence is strongly suppressed, is proposed and tested.Comment: Version accepted by J.Phys. G (2011

Application of nonextensive statistics to particle and nuclear physics

We present an overview of possible imprints of non-extensitivity in particle and nucler physics. Special emphasis is put on the intrinsic fluctuations present in the system under consideration as the possible source of nonextensivity. The possible connection of nonextensivity and the self organized criticality apparently being observed in some cosmic rays and hadronic experiments will also be discussed.Comment: Contribution to International School and Conference on "Non Extensive Thermodynamics and physical applications", Villasimius-Capo Boi (Cagliari), Italy, 23-30 March 200

Transverse momentum versus multiplicity fluctuations in high-energy nuclear collisions

We discuss recently measured event-by-event fluctuations of transverse momentum and of multiplicity in relativistic heavy-ion collisions. It is shown that the non-monotonic behavior of the p_T-fluctuations as a function of collision centrality can be fully explained by the observed non-monotonic multiplicity fluctuations. A possible mechanism responsible for the multiplicity fluctuations is also considered.Comment: 5 pages, 3 figures, revised & extended, to appear in Phys. Rev.

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.Comment: 11 pages, 7 figures and 1 table. This reworked version has been accepted for publication by EPJ

Effect of CT misalignment on attenuation — corrected myocardial perfusion SPECT

BACKGROUND: Use of CT based attenuation correction (AC) for myocardial perfusion SPECT (MPS) is growing fast due to a rapid development of hybrid SPECT/CT systems. SPECT and CT studies are performed in a sequential way extending total study acquisition and making a patient movement more likely. The present work aims at answering the question how large misalignment between SPECT and CT studies should be considered significant and how often those misregistrations are observed. MATERIAL AND METHODS: A retrospective study applying AC was performed in 107 patients who had coronary angiography (CA) performed within 3 months. Patients underwent a stress/rest Tc-99m MIBI 2 day SPECT/CT myocardial perfusion study. In case of SPECT and CT misalignment CT slices were shifted manually; shifts along 3 axes were recorded and after realignment a repeat reconstruction was performed. Euclidean distance of misalignment was also calculated. Images were analyzed by two experienced nuclear medicine specialists (consensus) applying visual semiquantitative method. Perfusion of three arteries was scored using a 5 grade scale. CA results were used as a reference for MPS findings. RESULTS: In 47 patients (44%) CT realignment was necessary. CT was shifted mostly along x and y axes, and less often along z axis. Euclidean distance S exceeded 2 pixels in 3 stress and 2 rest studies. Only in 7 patients changes of scores assigned to coronary vessels were noted as a result of CT realignment. These changes concerned 9 vessel areas. In 7 out of 9 cases changes were noted toward a better agreement with results of CA. Only in one patient, with stress S > 3 pixels and negative result of CA, CT realignment changed vessel area score significantly, from probably abnormal to normal. CONCLUSIONS: Only misalignments large enough, exceeding 2–3 pixels, have negative impact on attenuation corrected images. Such misalignments are rare, in our material were observed in 3 stress and 2 rest studies (3% and 2% of all studies, respectively). Only in one patient (below 1% of all studied patients) CT misalignment caused a significant study misinterpretation. Although alignment of SPECT and CT studies should be checked in every patient, small misalignments do not affect study interpretation

Numerical modelling of Bose-Einstein correlations

We propose extension of the algorithm for numerical modelling of Bose-Einstein correlations (BEC), which was presented some time ago in the literature. It is formulated on quantum statistical level for a single event and uses the fact that identical particles subjected to Bose statistics do bunch themselves, in a maximal possible way, in the same cells in phase-space. The bunching effect is in our case obtained in novel way allowing for broad applications and fast numerical calculations. First comparison with $e^+e^-$ annihilations data performed by using simple cascade hadronization model is very encouraging.Comment: LaTeX file and 5 eps file with figures, 9 pages altogethe