Searcharxiv⌕ Search

arXiv subjects

I. M. Dremin

Publications and source records attributed to I. M. Dremin.

At least 91 records · Page 5Linked to original sources
arXiv2004

QCD and hybrid NBD on oscillating moments of multiplicity distributions in lepton- and hadron-initiated reactions

QCD predictions for moments of multiplicity distributions are compared with experimental data on e+e- collisions and their two-NBD fits. Moments of the multiplicity distribution in a two-NBD model for 1.8 TeV pp collisions are considered. Three-NBD model predictions and fits for pp at LHC energies are also discussed. Analytic expressions for moments of hybrid NBD are derived and used to get insight into jet parameters and multicomponent structure of the processes. Interpretation of observed correlations is proposed.

hep-ph↗
arXiv2003

Jet calculus problems of the perturbative quantum chromodynamics

The perturbative quantum chromodynamics (pQCD) has been extremely successful in the prediction and description of main properties of quark and gluon jets. There are, however, some problems of the jet calculus with the higher order corrections of the modified perturbative expansion which should be resolved to get more precise statements. Some of them are discussed here.

hep-ph↗
arXiv2003

Is QCD asymptotically free?

The asymptotical behaviour of the QCD coupling strength is considered. Its upper bound is found from the present experimental data. The assumption about the finite asymptotical value of the coupling strength leads to the energy scale where the perturbative predictions would fail. Possible tests of this assumption are considered.

hep-ph↗
arXiv2003

Jet physics at LEP and QCD

With the advent of LEP we discovered jets and at its last years we learned a lot about intermediate vector bosons. All that strongly supports our belief in QCD. Jet physics is briefly described in this talk. Experimental results are compared with QCD predictions. It is shown that the perturbative QCD has been able not only to describe the existing data but also to predict many bright phenomena.

hep-ph↗
arXiv2002

Moments of the truncated multiplicity distributions

In experiment, the multiplicity distributions of inelastic processes are truncated due to finite energy, insufficient statistics or special choice of events. It is shown that the moments of such truncated multiplicity distributions possess some typical features.In particular, the oscillations of cumulant moments at high ranks and their negative values at the second rank can be considered as ones most indicative on specifics of these distributions. They allow to distinguish between distributions of different type.

hep-ph↗
arXiv2002

Multiparticle production and quantum chromodynamics

The theory of strong interactions, quantum chromodynamics (QCD), is quite successful in the prediction and description of main features of multiparticle production processes at high energies. The general perturbative QCD approach to these processes (mainly to e+e- -annihilation) is briefly formulated and its problems are discussed. It is shown that the analytical calculations at the parton level with the low-momentum cut-off reproduce experimental data on the hadronic final state in multiparticle production processes at high energies surprisingly accurately even though the perturbative expansion parameter is not very small. Moreover, it is important that the perturbative QCD has been able not only to describe the existing data but also to predict many bright qualitatively new phenomena.

hep-ph↗
arXiv2002

Cherenkov radiation by particles traversing the background radiatio n

High energy particles traversing the Universe through the cosmic microwave backgroung radiation can, in principle, emit Cherenkov radiation. It is shown that the energy threshold for this radiation is extremely high and its intensity would be too low due to the low density of the "relic photons gas" and very weak interaction of two photons.

astro-ph↗
arXiv2002

Some problems of the pQCD jet calculus

Some problems of the perturbative quantum chromodynamics (pQCD) jet calculus are discussed. The first one is related to the terminology of the order of calculation. Due to cancelation of LO and NLO terms in the ratio of mean multiplicities in gluon and quark jets $r$ the nowadays obtained results about it should be called as 4NLO approximation. The second problem reveals itself in calculations where corrections to some values (in particular, to $r'$) are larger at present energies than lower order terms. Some characteristics which do not suffer from this deficiency are proposed. Next problem lies in interpretation of the negative values of cumulant moments which are considered as an indication to the replacement of attraction by repulsion in sets with definite particle contents. Finally, the problem of the generalization of QCD equations for generating functions is briefly discussed.

hep-ph↗
arXiv2001

Parton and dipole approaches in QCD

Here, we discuss QCD predictions on multiplicities in parton and dipole approaches. The most general treatment is based on the notion of the generating functions. The generating function G is defined as $G(u,y)=\sum_nu^nP_n(y)$, where $P_n$ is the probability of the n-particle production at energy denoted by y, u is an auxiliary variable. The mean multiplicity and higher moments of the multiplicity distribution $P_n$ are given by the u-derivatives of G at u=1.

hep-ph↗
arXiv2001

Symmetries and wavelets

Wavelet analysis of different patterns reveals some symmetries and singularities otherwise hidden in the pattern. Its general methods are briefly reviewed. Examples from turbulence, cavitation, Cherenkov gluon emission and quark-gluon jets structure in QCD are considered.

hep-ph↗
arXiv2001

Wavelets and their use

This review paper is intended to give a useful guide for those who want to apply discrete wavelets in their practice. The notion of wavelets and their use in practical computing and various applications are briefly described, but rigorous proofs of mathematical statements are omitted, and the reader is just referred to corresponding literature. The multiresolution analysis and fast wavelet transform became a standard procedure for dealing with discrete wavelets. The proper choice of a wavelet and use of nonstandard matrix multiplication are often crucial for achievement of a goal. Analysis of various functions with the help of wavelets allows to reveal fractal structures, singularities etc. Wavelet transform of operator expressions helps solve some equations. In practical applications one deals often with the discretized functions, and the problem of stability of wavelet transform and corresponding numerical algorithms becomes important. After discussing all these topics we turn to practical applications of the wavelet machinery. They are so numerous that we have to limit ourselves by some examples only. The authors would be grateful for any comments which improve this review paper and move us closer to the goal proclaimed in the first phrase of the abstract.

hep-ph↗
arXiv2000

Status of ring-like correlations and wavelets

The problem of large-scale correlations of particles produced in high-energy collisions is discussed. Among them are, e.g., those correlations which lead to ring-like and elliptic flow shapes of individual high-multiplicity events in the polar+azimuthal angles plane. The wavelet method of analysis which allows to disentangle various patterns is proposed and applied to central Pb-Pb collisions at 158A GeV.

hep-ph↗
arXiv2000

Long-range particle correlations and wavelets

The problem of long-range correlations of particles produced in high- energy collisions is discussed. Long-range correlations involve large groups of particles. Among them are, e.g., those correlations which lead to ring-like and elliptic flow shapes of individual high-multiplicity events in the polar+azimuthal angles plane. The \w method of \an which allows to disentangle various patterns has been proposed and applied to some central lead-lead collisions at energy 158 GeV per nucleon. Previous attempts to find out the ring-like correlations and recent results on \w \an of high- energy nuclei interactions are reviewed.

hep-ph↗
arXiv2000

Hadron Multiplicities

We review results on hadron multiplicities in high energy particle collisions. Both theory and experiment are discussed. The general procedures used to describe particle multiplicity in Quantum Chromodynamics (QCD) are summarized. The QCD equations for the generating functions of the multiplicity distributions are presented both for fixed and running coupling strengths. The mean multiplicities of gluon and quark jets, their ratio, higher moments, and the slopes of multiplicities as a function of energy scale, are among the main global features of multiplicity for which QCD results exist. Recent data from high energy e+e- experiments, including results for separated quark and gluon jets, allow rather direct tests of these results. The theoretical predictions are generally quite successful when confronted with data. Jet and subjet multiplicities are described. Multiplicity in limited regions of phase space is discussed in the context of intermittency and fractality. The problem of singularities in the generating functions is formulated. Some special features of average multiplicities in heavy quark jets are described.

hep-ph↗
arXiv2000

Multiplicity distributions of quark and gluon jets in QCD

The solution of the equations for the generating functions of multiplicity distributions of quark and gluon jets in higher order 3NLO perturbative QCD is obtained. The non-perturbative effects are discussed as well. The results are compared to recent experimental data on mean multiplicities, their ratio and its slope, higher moments of the distributions.

hep-ph↗
arXiv2000

Wavelet-patterns in nucleus-nucleus collisions at 158A GeV

We propose to use {\it multidimensional} \w \an for pattern recognition in high multiplicity events and consider some examples. Wavelet analysis reveals clustering phenomena in multiparticle production processes. Results of event-by-event studies of some nucleus-nucleus collisions at 158A GeV are reported. The clusterization topology is found to be different in different events. Typical patterns include jets and ring-like structures. They are demonstrated here for five high multiplicity events.

hep-ph↗
arXiv2000

Wavelets on nuclear interactions and QCD on jet multiplicities

This talk at Fradkin conference is devoted to brief description of latest results in two topics I worked on during last years. The multiresolution analysis and fast wavelet transform became a standard procedure for pattern recognition and I describe how it has been used for analysis of high energy nucleus-nucleus interactions. Latest QCD results on multiplicities in quark and gluon jets are discussed and confronted to experimental data.

hep-ph↗