A relativistic coupled-channel formalism for the pion form factor

The electromagnetic form factor of a confined quark-antiquark pair is calculated within the framework of point-form relativistic quantum mechanics. The dynamics of theexchanged photon is explicitly taken into account by treating theelectromagnetic scattering of an electron by a meson as a relativistic two-channel problem for a Bakamjian-Thomas type mass operator. This approach guarantees Poincare invariance. Using a Feshbach reduction the coupled-channel problem can be converted into a one-channel problem for the elastic electron-meson channel. By comparing the one-photon-exchange optical potential at the constituent and hadronic levels, we are able to unambiguously identify the electromagnetic meson form factor. Violations of cluster-separability properties, which are inherent in the Bakamjian-Thomas approach, become negligible for sufficiently large invariant mass of the electron-meson system. In the limit of an infinitely large invariant mass, an equivalence with form-factor calculations done in front-form relativistic quantum mechanics is established analytically.Comment: 3 pages, 1 figure, submitted to EPJ Web of Conference

Point-form quantum field theory and meson form factors

We shortly review point-form quantum field theory, i.e. the canonical quantization of a relativistic field theory on a Lorentz-invariant surface of the form $x_\mu x^\mu = \tau^2$. As an example of how point-form quantum field theory may enter the framework of relativistic quantum mechanics we discuss the calculation of the electromagnetic form factor of a confined quark-antiquark pair (e.g. the pion).Comment: 3 pages, 2 figures. Based on a talk presented by W. Schweiger at the 20th European Conference on Few-Body Problems in Physics, September 10-14 2007, Pisa, Ital

The Analysis of the Chloride and Fluoride Influences on the Reducer Refinement Processes (Carbo-N-Ox) Aluminum Alloys

Slag refining slag with west materials was analysed used the DTA methods. In the paper a method of determining the reduction capability, with the Carbo-N-Ox method, of slag solutions was used. Some relations between the stimulators in the environment - slag - metal system allow to initiate mass exchange reactions in the process of slag refining.The presented in work course of behaviour permits on choice of basic composition of slaglite, the of necessary components stimulating quantities, as well as on accomplishment of opinion of ability refinement. The worked out programme Slag-Prop, after introduction of data with experiment, it allows on next corrections in composition of proposed mixtures also, should be put on properly elaborated factors of multistage reaction with essential usage of suitable stimulators

Solving QCD evolution equations in rapidity space with Markovian Monte Carlo

This work covers methodology of solving QCD evolution equation of the parton distribution using Markovian Monte Carlo (MMC) algorithms in a class of models ranging from DGLAP to CCFM. One of the purposes of the above MMCs is to test the other more sophisticated Monte Carlo programs, the so-called Constrained Monte Carlo (CMC) programs, which will be used as a building block in the parton shower MC. This is why the mapping of the evolution variables (eikonal variable and evolution time) into four-momenta is also defined and tested. The evolution time is identified with the rapidity variable of the emitted parton. The presented MMCs are tested independently, with ~0.1% precision, against the non-MC program APCheb especially devised for this purpose.Comment: version compatible with with the erratum in Acta Physica Polonic

Analiza vjerojatnosti procjene ekološke prikladnosti troske korištenjem baze podataka

This article contains information concerning of the analysis the possibility of defining refinery qualities of the slag based of the thermo-physical and thermodynamical data. The issues presented deals not only with refining copper and melting stages, but also of the idea building an optimization program. In its assumption the program is supposed to check and search specific data very quickly on the particular types of slag. There are possible and purposeful the construction optimization programme engaging all of the physics chemical influence the slag in processes of melting metals alloys. The proposed results, ranges of areas on graphs of phase equilibria’s, demonstrative on the optimum values, will be verified in laboratory conditions and industrial. The initiation the new data the gathered base will be built in system of open base enabling.Rad sadrži informacije koje se odnose na analizu vjerojatnosti defi niranja rafi nacijske sposobnosti troske koja se temelji na termofizikalnim i termodinamičkim podacima. Prikazani rezultati ne odnose se samo na rafi naciju bakra i stupnjeve taljenja, već također i na ideju gradnje optimizacijskog programa. Pod tom pretpostavkom programom je predviđeno da se provjeri i istraži određeni podatak vrlo brzo za pojedinu vrstu troske. Moguća je i svrsishodna gradnja optimizacijskog programa koji uključuje sve fi zikalne i kemijske utjecaje troske u procesu taljenja metalnih slitina. Predloženi rezultati, područja površina na grafovima faznih ravnoteža, izrazito na optimalnim vrijednostima, bit će verifi cirani u laboratorijskim i industrijskim uvjetima. Uvođenjem novih podataka sakupljene baze ugradit će se u sustav baze otvorene mogućnosti

Analysis of the possibility of estimation ecological slag propriety with use the database

This article contains information concerning of the analysis the possibility of defi ning refi nery qualities of the slag based of the thermo-physical and thermodynamical data. The isues presented deals not only with refi ning copper and melting stages, but also of the idea building an optimization program. In its assumption the program is supposed to check and search specifi c data very quickly on the particular types of slag. There are possible and purposeful the construction optimization programme engaging all of the physics chemical infl uence the slag in processes of melting metals alloys. The proposed results, ranges of areas on graphs of phase equilibria’s, demonstrative on the optimum values, will be verifi ed in laboratory conditions and industrial. The initiation the new data the gathered base will be built in system of open base enabling

Reggeon and pion contributions in semi-exclusive diffractive processes at HERA

A detailed analysis of semi-exclusive diffractive processes in e-p DIS at HERA, with the diffractive final states in the forward direction is presented. The contributions of the subleading f_2, \omega, a_2, \rho reggeons and the pion exchanges to the diffractive structure function with the forward proton or neutron are estimated. It is found that the (a_2,\rho) reggeons are entirely responsible for the forward neutron production at x_P < 10^{-3}. The \pi N production in the forward region is estimated using the Deck mechanism. The significance of this reaction for the processes measured at HERA, especially with the leading neutron, is discussed.Comment: Strongly revised version accepted for publication in Phys.Rev.D. Latex, 14 pages with 5 eps figures include

Mapping the proton unintegrated gluon distribution in dijets correlations in real and virtual photoproduction at HERA

We discuss how the dijet azimuthal correlations in DIS and real photoproduction at HERA probe the differential (unintegrated) gluon distribution in the proton. We find a strong dependence of the azimuthal correlation pattern on Bjorken-$x$, photon virtuality and the cut on the jet transverse momenta. A rise of the azimuthal decorrelations is observed with decreasing Bjorken-x due to the interplay of perturbative and nonperturbative effects. We predict a strong rise of the same-side jet rate with photon energy for real photoproduction. We discuss conditions for the correlation function to be dominated by hard perturbative gluons and ways of constraining the size of the nonperturbative soft component. We make some predictions for the THERA energy range. The analysis of the energy dependence of the isolated jet and two-jet cross sections in photoproduction would be a new way to study the not yet well constrained unintegrated gluon distributions and to explore the onset of the pQCD regime.Comment: 16 pp, 8 eps-fig