arXiv subjects

V. A. Okorokov

Publications and source records attributed to V. A. Okorokov.

At least 37 records · Page 2Linked to original sources

arXiv2016

Geometry and space-time extent of pion emission region at FCC energies

The energy dependence is investigated for a wide set of space-time characteristics derived from Bose - Einstein correlations of secondary pion pairs produced in proton-proton and nucleus-nucleus interactions. Analytic functions suggested for smooth approximations of the energy dependence of emission region parameters demonstrate reasonable agreement with all available experimental results for proton-proton collisions while the approximations correspond to most of experimental data for nucleus-nucleus collisions at energies above 5 GeV. Estimations for a wide set of space-time quantities are obtained for energies for the Future Circular Collider (FCC) project based on the smooth approximations. The space particle densities at freeze-out are derived also from estimations for the volume of the emission region and for total multiplicity at FCC energies. Estimations for charged particle density and its critical value allow the possibility of lasing behavior for secondary pions in nucleus-nucleus collisions at FCC energy. The mathematical formalism is presented for study of the peak shape of correlation function for general case of central-symmetrical Levy - Feldheim distribution.

hep-ph↗

arXiv2016

The energy dependence of the chaoticity $λ$ parameter from BEC of $π$-pairs produced in $pp$ collisions

The $\sqrt{s_{pp}}$ behavior of the chaoticity parameter $λ$, derived from Bose - Einstein Correlations (BEC) of pion-pairs produced in $pp$ collisions, is investigated. Considered are the one and three dimensions (1D, 3D) of the BEC analyzed in terms of a Gaussian and/or Exponential distributions. A marked difference is observed between the $λ$ dependence on energy in the 1D and the 3D analyzes. The experimental data are examined in terms of the relation between the pion cluster of sources and the BEC dimension R which in turn are deduced from the charged outgoing particle multiplicity. While in this approach the general decrease with energy of the 1D $λ$ is accounted for it fails to represent the few 3D $λ$ data which are seen to remain constant with energy above $\sim$200 GeV.

hep-ph↗

arXiv2016

NICA-MPD: azimuthal and femtoscopic particle correlations

The discussion is focused on the study of the fundamental symmetries ($\mathcal{P/CP}$) of QCD and geometry of the particle source. The combination of correlators corresponding to the absolute asymmetry of distribution of electrically charged particles with respect to the reaction plane in heavy ion collisions is studied. A significant decrease of the absolute asymmetry is observed in the intermediate energy range which can be considered as indication of possible transition to predominance of hadronic states over quark-gluon degrees of freedom in the mixed phase created in heavy ion collisions at intermediate energies. For the investigation of the energy evolution of the geometric properties of the particle source the use of femtoscopic radii scaled on the averaged radius of colliding ions is suggested. This approach allows the expansion of the set of interaction types, in particular, on the collisions of non-symmetrical ion beams which can be studied within the framework of common treatment. There is no sharp changing of femtoscopic parameter values with increasing of the initial energy. The suggestions are made for future advancement of these studies on NICA-MPD.

nucl-ex↗

arXiv2016

NICA fixed target mode: soft jet studies in the relative 4-velocity space

Experimental results obtained by studying the properties of soft jets in the 4-velocity space at $\sqrt{s} \sim 2-20$ GeV are presented. The changes in the mean distance from the jet axis to the jet particles, the mean kinetic energy of these particles, and the cluster dimension in response to the growth of the collision energy are consistent with the assumption that quark degrees of freedom manifest themselves in processes of pion jet production at intermediate energies. The energy at which quark degrees of freedom begin to manifest themselves experimentally in the production of soft pion jets is estimated for the first time. The estimated value of this energy is $2.8 \pm 0.6$ GeV. The suggestions are made for future investigations on NICA.

hep-ex↗

arXiv2016

Energy dependence of femtoscopy properties of pion source in nuclear collisions

In the paper energy dependence of femtoscopy characteristics of pion emission region at freeze-out is investigated for collisions of various ions and for all experimentally available energies. For the first time the normalized values of radii and volume of source are used for energy dependence. This approach allows us to expand the set of interaction types, in particular, on non-symmetrical nucleus-nucleus collisions which can be studied in the framework of common approach. There are no the sharp changing of femtoscopic parameter values, in particular, $R_{o}/R_{s}$ with increasing of $\sqrt{s_{NN}}$ which were predicted by some phenomenological models as signature of first order phase transition in strongly interacting matter. The generalized parameterization for femtoscopic correlation function is suggested.

nucl-ex↗

arXiv2015

Energy dependence of slope parameter in elastic nucleon-nucleon scattering

The study of slope parameter is presented for elastic proton-proton and antiproton-proton scattering with taking into account the resent experimental data at high energies. The expanded logarithmic approximations allow the description of the experimental slopes in all available energy range reasonably. Accounting for the LHC results leads to the dramatic change of behavior of the quadratic in logarithm approximation at high energies and to the closer trends for all fitting functions under study in comparison with the analysis at collision energies up to the 200 GeV. The estimations of the asymptotic shrinkage parameter $α'_{\cal{P}}$ are discussed. Predictions for diffraction slope parameter are obtained for some proton-proton and antiproton-proton facilities.

hep-ph↗

arXiv2015

Energy dependence of space-time extent of pion source in nuclear collisions

Energy dependence of space-time parameters of pion emission region at freeze-out is studied for collisions of various ions and for all experimentally available energies. The using of femtoscopic radii scaled on the averaged radius of colliding ions is suggested. This approach allows the expansion of the set of interaction types, in particular, on collisions of non-symmetrical ion beams which can be studied within the framework of common treatment. There is no sharp changing of femtoscopic parameter values with increasing of initial energy. Analytic functions suggested for smooth approximations of energy dependence of femtoscopic parameters demonstrate reasonable agreement with most of experimental data at $\sqrt{s_{NN}} \geq 5$ GeV. Estimations of some observables are obtained for energies of the LHC and FCC project.

nucl-ex↗

arXiv2014

Slope analysis for elastic nucleon-nucleon scattering

The diffraction slope parameter is investigated for elastic proton-proton and proton-antiproton scattering based on the all available experimental data at low and intermediate momentum transfer values. Energy dependence of the elastic diffraction slopes is approximated by various analytic functions. The expanded "standard" logarithmic approximations with minimum number of free parameters allow to describe experimental slopes in all available energy range reasonably. The estimations of asymptotic shrinkage parameter $α'_{\cal{P}}$ were obtained for various $|t|$ domains based on the all available experimental data. Various approximations differ from each other both in the low energy and very high energy domains. Predictions for diffraction slope parameter are obtained for elastic proton-proton scattering at NICA, RHIC and LHC energies, for proton-antiproton elastic reaction in FAIR energy domain for various approximation functions.

hep-ph↗

arXiv2014

Strongly interacting matter at RHIC: experimental highlights

Recent experimental results obtained at the Relativistic Heavy-Ion Collider (RHIC) will be discussed. Investigations of different nucleus-nucleus collisions in recent years focus on two main tasks, namely, the detailed study of sQGP properties and the exploration of the QCD phase diagram. Results at top RHIC energy provide important information about event shapes as well as transport and thermodynamic properties of the hot medium for various flavors. Heavy-ion collisions are a unique tool for the study of topological properties of theory. Experimental results obtained for discrete QCD symmetries at finite temperatures are discussed. These results confirm indirectly the topologically non-trivial structure of the QCD vacuum. Most results obtained during phase-I of the RHIC beam energy scan (BES) program show smooth behavior vs initial energy. However, certain results suggest the transition in the domain of dominance of hadronic degrees of freedom at center-of-mass energies between 10-20 GeV. Future developments and more precise studies of features of the QCD phase diagram in the framework of phase-II of RHIC BES will be briefly discussed.

nucl-ex↗

arXiv2014

Azimuthally integrated HBT parameters for charged pions in nucleus-nucleus interactions versus collision energy

In the paper energy dependence of space-time extent of emission region obtained from Bose - Einstein correlations is studied for charged pions in various ion collisions for all experimentally available energies. There is no dramatic change of HBT parameters with increasing of collision energy per nucleon-nucleon pair, $\sqrt{s_{NN}}$, in domain of energies $\sqrt{s_{NN}} \geq 5$ GeV. Energy dependence of estimations for emission duration is almost flat for all energy domain under study within large error bars. Analytic function is suggested for smooth approximation of energy dependence of main HBT parameters. Fit curves demonstrate reasonable agreement with experimental data for most HBT parameters in energy domain $\sqrt{s_{NN}} \geq 5$ GeV. Estimations of some observables are obtained for energies of the LHC and FCC project.

nucl-ex↗

arXiv2013

Influence of Fractal Embedding in Three-Dimensional Euclidean Space on Wave Propagation in Electro- Chromodynamics

In this paper two zero-dimensional compact sets with equal topological and fractal dimensions but embedded in Euclidean space by different ways are under study. Diffraction of plane electromagnetic wave propagated and reflected by fractal surfaces is considered for each of these compact sets placed in vacuum. It is obtained, that the embedding of compact influences on characteristics of wave in final state. Thus, the embedding of Cantor set in Euclidean space is additional property of a fractal which can be important both for applications of fractal electrodynamics and for physics of strong interactions.

nucl-th↗

arXiv2013

Dependence of soft pion jet properties in the space of relative four-dimensional velocities on initial energy

In the paper experimental results obtained by studying of collective and fractal properties of soft pion jets in the space of relative four-dimensional velocities in intermediate energy domain 2 - 20 GeV are presented. Fractional values of cluster dimension are indicated on manifestation of fractal-like properties by pion jets. The changes of the mean square of the distance between secondary particles and jet axis, the mean kinetic energy of particles in jets and the cluster dimension with increasing of collision energy agree with the hypothesis of manifestation of quark degrees of freedom in processes of pion jet production at intermediate energies. For the first time the quantitative estimations are obtained for the low boundary energy at which quark degrees of freedom start to display itself in production of soft pion jets experimentally. The value of estimation for this parameter derived with taking into account of all used collective parameters is (2.8 \pm 0.6) GeV.

nucl-ex↗

arXiv2013

Dependence of asymmetries for charge distribution with respect to the reaction plane on initial energy in heavy ion collisions

In the paper two combinations of correlators are defined in order to investigate the evolution of possible $\mathcal{P/CP}$ invariance violation in strong interactions with initial energy for heavy ion collisions. These combinations correspond to absolute and relative asymmetry of distribution of electrically charge particles with respect to the reaction plane in heavy ion collisions. Energy dependence of the parameters was derived from data of STAR and ALICE experiments. Significant decreasing both absolute and relative asymmetry is observed at energies $\sqrt{s_{NN}} < 20$ GeV. This feature agrees qualitatively with other results of stage-I beam energy scan program in STAR experiment. General behavior of dependence of absolute asymmetry on initial energy agree reasonably with behavior of similar dependence of Chern -- Simons diffusion rate calculated at different values of external Abelian magnetic field. The observed behavior of understudying parameters vs energy can be considered as indication on possible transition to predominance of hadronic states over quark-gluon degrees of freedom in the mixed phase created in heavy ion collisions at intermediate energies.

nucl-ex↗

arXiv2011

Event shapes for hadronic final state: experimental review

Analysis is presented for first moments of collective observable distributions in two-jet events for various interaction types and for wide initial energy range. These variables include sphericity, thrust, components of transverse particle momentum, alignment and planarity. Analytical functions are suggested for description of energy dependence for all collective variables under study with exception of infrared-stable thrust variable. Energy dependence for average thrust is compared with predictions of dispersive model and single dressed gluon approximation. Estimations of strong coupling constant obtained in the paper are in reasonable agreement both with world average value and with results extracted by other methods. Usually, multiplicity dependence of collective variables under study agree with power function at energies less than 12 GeV at qualitative level.

hep-ph↗

arXiv2010

Phenomenological Analysis of $pp$ and $\bar{p}p$ Elastic Scattering Based on Theoretical Bounds in High-Energy Physics

Considering the Froissart-Martin bound, Jin-Martin-Cornille bound and the optical theorem, we propose a novel parametrization for the total cross-section of proton-proton and antiproton-proton elastic scattering data. Using derivative dispersion relations we obtain the real part of the elastic scattering amplitude and thus the $ρ$ parameter. Simultaneous fits to $σ_{tot}$ and $ρ$ are performed allowing very good statistical descriptions of the available data. Furthermore, predictions to $σ_{tot}$ and $ρ$ at energies not used in the fit procedures are presented. For $σ_{tot}$ we obtain predictions at RHIC, LHC and future HC energies.

hep-ph↗

arXiv2010

Estimation of P-odd correlators in heavy ion collisions at RHIC energies 62.4 -- 200 GeV

The strength of parity violation effect can be characterized by correlator value in the framework of local $\mathcal{TIP}$ hypothesis. The energy and centrality dependencies of correlators for same and opposite charges are discussed for heavy ion collisions in RHIC energy domain 62.4 -- 200 GeV. The magnetic field shows a significant increasing at initial energy decreasing for intermediate and large times. Two possible scenarios for initial time are investigated in detail. Both scenarios predict the most close values for initial time in ${Au+Au}$ collisions at 62.4 GeV. Disagreement between initial time values obtained for two various scenarios increases with energy increasing and for collisions of lighter ${Cu}$-nucleus. Boundary values for correlators related with possible local $\mathcal{TIP}$ violation are calculated in the framework of analytic approach of chiral magnetic effect for ${Au+Au}$ collisions at 62.4 and 200 GeV. The results are shown as function of collision centrality. Preliminary experimental STAR data are compared with predictions of chiral magnetic effect model directly. Experimental signals consistent with model expectations for both same and opposite charge correlations in ${Au+Au}$ collisions at 62.4 GeV at all centralities. At higher energy 200 GeV the model of chiral magnetic effect underestimates same charge correlator values for central and midcentral events but the same charge correlations for peripheral events as well as opposite charge correlations are in the boundaries predicted by model calculations.

nucl-th↗

arXiv2010

Collective and fractal properties of pion jets in the four-velocity space at intermediate energies

Experimental results are presented for study of collective and fractal properties of soft pion jets in the space of relative four-dimensional velocities. Significant decreasing is obtained for mean square of second particle distances from jet axis for pion-proton interactions at initial energies $\sim 3$ GeV in comparison with hadron-nuclear collisions at close energies. The decreasing results in power dependence of distance variable on collision energy for range $\sim 2 - 4$ GeV. The observation allows us to estimate the low boundary of manifestation of color degree of freedom in pion jet production. Cluster dimension values were deduced for pion jets in various reactions. Fractional values of this dimension indicate on the manifestation of fractal-like properties by pion jets. Changing of mean kinetic energy of jet particles and fractal dimension with initial energy increasing is consistent with suggestion for presence of color degrees of freedom in pion jet production at intermediate energies.

nucl-ex↗

arXiv2008

Slope analysis for elastic proton-proton and proton-antiproton scattering

The diffraction slope parameter is investigated for elastic proton-proton and proton-antiproton scattering based on the all available experimental data at intermediate square of momentum transfer in the main. Energy dependence of the elastic diffraction slope is approximated by various analytic functions in a model-independent fashion. The expanded standard logarithmic approximations allow to describe experimental slopes in all available energy range at qualitative level reasonably. Various fitting functions differ from each other both in low energy and very high energy domains. Predictions for diffraction slope parameter are obtained for elastic proton-proton scattering at NICA, RHIC and LHC energies, for proton-antiproton elastic reaction in FAIR energy domain for various approximation functions at intermediate square of momentum transfer. Difference of nuclear slopes for proton-antiproton and proton-proton scattering is investigated in wide momentum transfer range also.

hep-ph↗