Search

We show that extraction of the quantities} $\rho(s)=\mbox{Re}[T_{N}(s,0)]/\mbox{Im}[T_{N}(s,0)]$ {\it and} $\sigma_{\mbox{tot}}(s)$ {\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., Comment: A small edit of the drawing

We describe a general Godunov type splitting for numerical simulations of the Fisher/Kolmogorov-Petrovski-Piskunov growth and diffusion equation in two spatial dimensions. In particular, the method is appropriate for modeling population growth and dispersal on a terrestrial map. The procedure is semi-implicit, hence quite stable, and approximately second order accurate, excluding boundary condition complications. It also has low memory requirements and shows good performance. We illustrate an application of this solver: global human dispersal in the late Pleistocene, modeled via growth and diffusion over geographical maps of paleovegetation and paleoclimate., Comment: 27 pages, 12 figures

It is shown that using the relativistic field theory of gravity (RTG) and measured value of $\Omega_{tot}$ one can obtain the upper limit on the graviton mass with 95%C.L.: $m\leq 1.6\cdot 10^{-66}$ [g]; within the $(1\sigma)$ range its probable value is $m_{g}= 1.3\cdot 10^{-66}$ [g]. It is pointed out that according to RTG the presence of the quintessence is necessary to explain the Universe accelerated expansion. Experimental data on the Universe age and dark matter density allow one to determine the range of possible values of the $\nu$ parameter in the equation of quintessence state and indicate characteristic time, which corresponds to the beginning and cessation of the accelerated expansion epoch, as well as the time period of the maximal expansion, which corresponds to the half-period of the oscillatory evolution of the Universe., Comment: 17 pages, 4 jpeg figures

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., Comment: 17 pages, LaTeX2e, 8 EPS figures, Presented at the Second International "Cetraro" Workshop & NATO Advanced Research Workshop "Diffraction 2002", Alushta, Crimea, Ukraine, August 31 - September 6, 2002, see also http://nuclth02.phys.ulg.ac.be/compete/

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%., Comment: 11 pages, 2 figures, LaTeX, presented at the Second International "Cetraro" Workshop & NATO Advanced Research Workshop "Diffraction 2002", Alushta, Crimea, Ukraine, August 31 - September 6, 2002

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., Comment: 3 pages, 3 tables. To be published in the Proceedings of the 31st International Conference on High Energy Physics (ICHEP 2002), Amsterdam, The Netherlands, 24-31 July 2002

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%., Comment: 11 pages, 2 figures, 4 tables, RevTeX4

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., Comment: 13 pages, COMPETE Collaboration, talk presented at the 9th International Conference (Blois Workshop) on Elastic and Diffractive Scattering

We develop five new statistical measures of the quality of fits, which we combine with the usual confidence level to determine the models which fit best all available data for total cross sections and for the real part of the forward hadronic amplitude., Comment: 7 pages, presented by J.R. Cudell on behalf of the COMPETE collaboration at the 6th workshop on non-perturbative QCD, American University of Paris, 5-9 June 2001

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., Comment: 11 pages, 2 tables, Presented at the 9th Blois Workshop on Elastic and Diffractive Scattering, Pruhonice, Czech Republic, 9-15 June 2001

We consider several classes of analytic parametrisations of hadronic scattering amplitudes, and compare their predictions to all available forward data (p p, pbar p, pi p, K p, gamma p, gamma gamma, Sigma p). Although these parametrisations are very close for sqrt(s) > 9 GeV, it turns out that they differ markedly at low energy, where a universal pomeron term ~log^2(s) enables one to extend the fit down to sqrt(s)=4 GeV., Comment: 33 pages. Notations revised, clarified and corrected, appendix added with the formulae used, one reference added, typos corrected

Using the largest data set available, we determine the best values that the data at t=0 (total cross sections and real parts of the hadronic amplitudes) give for the intercepts and couplings of the soft pomeron and of the rho/omega and a/f trajectories. We show that these data cannot discriminate between a simple-pole fit and asymptotic log square s and log s fits, and hence are not sufficient to reveal the ultimate nature of the pomeron. However, we evaluate the existing evidence (factorization, universality, quark counting) favouring the simple-pole hypothesis. We also examine the range of validity in energy of the fits, and show that one cannot rely on such fits in the region sqrt(s)<9 GeV. We also establish bounds on the odderon and the hard pomeron., Comment: 20 pages, 10 figures. Predictions of Table 4 corrected and acknowledgements added

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., Comment: 13 pages, LaTeX, 14 figures. Presented by K. Kang at a 4th Workshop on Quantum Chromodynamics, June 1 - 6, 1998, The American University of Paris, Paris, France, and at the 4th Workshop on Small-x and Diffractive Physics, September 17 - 20, 1998, Fermi National Accelerator Laboratory, Batavia, IL