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V. V. Ezhela

Publications and source records attributed to V. V. Ezhela.

15 recordsLinked to original sources

On the $ ρ$ and $ σ_{tot} $ measurement by the TOTEM Collaboration: in the wake of recent discoveries

We show that extraction of the quantities} $ρ(s)=\mbox{Re}[T_{N}(s,0)]/\mbox{Im}[T_{N}(s,0)]$ {\it and} $σ_{\mbox{tot}}(s)$ {\it from the data on the $pp$ differential cross-section at $\sqrt{s} = 13$} TeV {\it obtained by the} TOTEM {\it Collaboration gives results essentially different from those presented in publication} \cite{Ant} {\it if to use a modified formula for Coulomb-nuclear interference. The physical interpretation of these data changes accordingly.

hep-ph↗

The Inconstancy of the Fundamental Physical Constants: Computational Status

It is argued that the CODATA recommended values of the fundamental physical constants could not be used as the reference data in searching the hypothetical space-time variations of the fundamental physical constants. It is shown that the CODATA data permanently suffers a loss of self-consistency of the released data due to unjustified over-rounding of their estimates. The simple estimates of the critical numbers of decimal digits that should be saved in the independently rounded correlation coefficients, the average values and uncertainties to save the self-consistency is obtained. The set of high level quality requirements to the computerized presentation of the numerical data on the jointly measured or estimated physical values are formulated. It is argued (once again) that the common standard for presentation of the numerical values of correlated quantities in publications and sites is urgently needed.

physics.data-an↗

Hadronic Part of the Muon g-2 Estimated on the sigma_tot^2003(e+ e- --> hadrons) Evaluated Data Compilation

A comprehensive as of November 2003 and evaluated data compilation on sigma_tot(e+ e- --> hadrons) was used to estimate the lowest order hadronic contribution to the muon anomalous magnetic moment. The preliminary result is a_mu(had, LO) = (699.6 +- 1.9(rad) +- 2.0(proc) +- 8.5(e+e-)) * 10^-10 The Standard Model value of the muon magnetic anomaly calculated by updated SM formulae published or e-printed by November 2003 then reads a_mu = (1 165 918 3.5 +- 8.7(had) +- 4.0(LbL) +- 0.3(QED) +- 0.2(EW)) * 10^-10. This result deviates from the current experimental world average of a_mu by (-19.5 +- 9.6(theor) +- 8.0(exp)) * 10^-10, i.e. at 1.5 sigma level.

hep-ph↗

On the CODATA Recommended Values of the Fundamental Physical Constants: V3.2(1998) & V4.0(2002)

With the help of special program package PAREVAL designed in {\sl Mathematica} system we reproduce values of basic fundamental physical constants obtained by NIST and recommended by CODATA for international usage since 1998. In our adjustment we use the input data and methods published by NIST in 1998. It is shown, that the detected earlier inaccuracy of published by NIST correlations (that made the NIST 1998&2002 results doubtful) are, most probably, due to inadmissible independent rounding. The simple estimate of the critical numbers of decimal digits in the independently rounded correlation coefficients is obtained. Further independent rounding of ``critically rounded'' correlations can lead to the non positive semi definite correlation matrices and hence is inadmissable. It is demonstrated by a few examples that the poor presentation of the correlated random quantities in the scientific literature is a common bad practice and is argued (once again) that the common standard for presentation numerical values of correlated quantities in publications and sites is urgently and badly needed.

physics.data-an↗

Overview of the COMPETE Program

Nowadays, scientific databases have become the bread-and-butter of particle physicists. These databases must be maintained and checked repeatedly to insure the accuracy of their content. The COMPETE collaboration aims at motivating data maintenance via the interfacing of theory and experiment at the database level. The database concept then needs to be supplemented by a "model-base". Such an object enables one not only to decide what the best description may be, but also to discern what potential problems exist in the data. The systematization of such a cross-fertilization between models and data results in the "object of knowledge" that is the point at which all existing information resources on a given problem could converge. There are many advantages to such a global approach. First of all, the maintenance of a data set is not a static task: it needs to be motivated by physics. The second advantage is that one can have a common testing ground for theories and models. Thirdly, an extensive theoretical database can be used to plan new experiments and to predict various quantities. Finally, as new data come in, one can very quickly decide on their theoretical impact, and hence immediately evaluate the need for new physics ideas. As we want to treat a large amount of data and many models, computer technology constitutes an important part of our activity. We have concentrated on the elaboration of artificial intelligence decision-making algorithms, as well as on the delivery of computer tools for the end-user. Further linkage with existing databases, such as PDG, COMPAS, and HEPDATA is being developed or planned.

hep-ph↗

Forward observables at RHIC, the Tevatron run II and the LHC

We present predictions on the total cross sections and on the ratio of the real part to the imaginary part of the elastic amplitude (rho parameter) for present and future pp and pbar p colliders, and on total cross sections for gamma p -> hadrons at cosmic-ray energies and for gamma gamma -> hadrons up to sqrt(s)=1 TeV. These predictions are based on a study of many possible analytic parametrisations and invoke the current hadronic dataset at t=0. The uncertainties on total cross sections, including the systematic theoretical errors, reach 1% at RHIC, 3% at the Tevatron, and 10% at the LHC, whereas those on the rho parameter are respectively 10%, 17%, and 26%.

hep-ph↗

Analytic Amplitudes for Hadronic Forward Scattering : COMPETE Update

We consider several classes of analytic parametrizations of hadronic scattering amplitudes, and compare their predictions to all available forward data in hadron-hadron, gamma-p and gamma-gamma reactions. Although these parametrizations are very close for SQRTs larger than 9 GeV, it turns out that they differ markedly at low energy, where a universal Pomeron term like ln**2 s enables one to extend the fit down to SQRTs equal to 4 GeV. We present predictions on the total cross sections and on the ratio of the real part to the imaginary part of the elastic amplitude (RHO parameter) for present and future pp and antipp colliders, and on total cross sections for gamma-p into hadrons at cosmic-ray energies and for gamma-gamma into hadrons up to SQRTs equal to 1 TeV.

hep-ph↗

Benchmarks for the Forward Observables at RHIC, the Tevatron-run II and the LHC

We present predictions on the total cross sections and on the ratio of the real part to the imaginary part of the elastic amplitude (rho parameter) for present and future pp and pbar p colliders, and on total cross sections for gamma p -> hadrons at cosmic-ray energies and for gamma gamma-> hadrons up to sqrt{s}=1 TeV. These predictions are based on an extensive study of possible analytic parametrisations invoking the biggest hadronic dataset available at t=0. The uncertainties on total cross sections, including the systematic errors due to contradictory data points from FNAL, can reach 1.9% at RHIC, 3.1% at the Tevatron, and 4.8% at the LHC, whereas those on the rho parameter are respectively 5.4%, 5.2%, and 5.4%.

hep-ph↗

Total Cross Sections of e+ e- --> hadrons and pQCD Tests

In the light of recent muon (g-2) result by the E821 experiment at BNL, the importance of and interest in the total hadronic cross sections in e+ e- collisions and R(e+ e- --> hadrons) have been heightened. We report on the integrated data compilation of available data of e+ e- --> hadrons, transformed to a unique and meaningful style that implements the pure QED radiative corrections, from the PPDS and HEPDATA databases by the COMPETE Group. In particular, the continuum data sets are extracted where the direct comparison of the parton models and different variants of the pQCD corrections can be made and which will be useful for the future refinements of alpha_s(Q^2) and alpha_QED(Q^2).

hep-ph↗

Analytic Amplitude Models for Forward Scattering

We report on fits of a large class of analytic amplitude models for forward scattering against the comprehensive data for all available reactions. To differentiate the goodness of the fits of many possible parametrizations to a large sample of data, we developed and used a set of quantitative indicators measuring statistical quality of the fits over and beyond the typical criterion of the $\Chi^2 /dof$. These indicators favor models with a universal $ log^2 s$ Pomeron term, which enables one to extend the fit down to $\sqrt s = 4$ GeV.

hep-ph↗

Analytic parametrizations of the non-perturbative Pomeron and QCD-inspired models

We consider several classes of analytic parametrizations of hadronic scattering amplitudes, and compare their predictions to all available forward data (proton- proton, antiproton-proton, pion-proton, kaon-proton, photon-proton, photon- photon, sigma-proton). Although these parametrizations are very close for energy larger than 9 GeV, it turns out that they differ markedly at low energy, where a universal Pomeron term ~(ln s)**2 enables one to extend the fit down to 4 GeV.

hep-ph↗

A compilation of total cross section data on e^+ e^- --> hadrons and pQCD tests

All available data on the total cross sections and R-ratio of e^+ e^- --> hadrons are compiled from the PPDS(DataGuide), PPDS(ReacData) and HEPDATA(Reaction) databases and transformed to a compilation of data on the e^+ e^- --> quark antiquark --> hadrons in the continuum region which can be used in tests of the parton model and pQCD calculations. This evaluated data compilation is made available in PPDS system and is accessible through the Web. It is shown that current predictions from the parton model and pQCD are well supported by this world "continuum" data compilation which can then be used in future refinements of the alpha_s(Q^2) as well as alpha_{QED}(Q^2) evolution forms.

hep-ph↗

Reanalysis of ep Elastic Scattering Data in Terms of Proton Electromagnetic Formfactors

We have made the comparison of three parametrizations of the proton electromagnetic form factors in the space-like region using the largest data set on $e^{\pm} p$ elastic scattering ever used. All models have a correct analytical structure with a minimal set of well known singularities. For the first time an effective two-pion intermediate coulombic bound state (pionium) was included into GVMD for nucleon formfactors. For the proton charge radius an estimate derived from our best fits is as follows: r_E^p [\rm fm] = 0.897 \pm 0.002(exp) \pm 0.001(norm) \pm 0.003(models). The traditional ``model independent'' fit by quadratic polynomial gives, in our estimation technology, a much cruder estimate r^p_{E,polinomial} [\rm fm] = 0.887 \pm 0.006(exp) \pm 0.096(norm). Both estimates are closer to the value estimated from the recent hydrogen Lamb shift measurements.

hep-ph↗

Soft Pomeron and Lower-Trajectory Intercepts

We present a preliminary report on the determination of the intercepts and couplings of the soft pomeron and of the rho/omega and f/a trajectories from the largest data set available for all total cross sections and real parts of the hadronic amplitudes. Factorization is reasonably satisfied by the pomeron couplings, which allows us to make predictions on gamma gamma and gamma p total cross sections. In addition we show that these data cannot discriminate between fits based on a simple Regge pomeron-pole and on an asymptotic log^2s-type behaviour, implying that the effect of unitarisation is negligible. Also we examine the range of validity in energy of the fit, and the bounds that these data place on the odderon and on the hard pomeron.

hep-ph↗