403 research outputs found
Calculation of the real part of the nuclear amplitude at high s and small t from the Coulomb amplitude
A new method for the determination of the real part of the elastic scattering
amplitude is examined for high energy proton-proton at small momentum transfer.
This method allows us to decrease the number of model assumptions, to obtain
the real part in a narrow region of momentum transfer and to test different
models. The possible non-exponential behavior of the real part was found on the
base of the analysis of the ISR experimental data.Comment: 5 pages, 3 figures, Talk on XIth International Conference on Elastic
and Diffractive Scatterin
A Possible Two-Component Structure of the Non-Perturbative Pomeron
We propose a QCD-inspired two-component Pomeron form which gives an excellent description of the proton-proton, pi-proton, kaon-proton, gamma-proton and gamma-gamma total cross sections. Our fit has a better CHI2/dof for a smaller number of parameters as compared with the PDG fit. Our 2-Pomeron form is fully compatible with weak Regge exchange-degeneracy, universality, Regge factorization and the generalized vector dominance model
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.Comment: 11 pages, 2 tables, Presented at the 9th Blois Workshop on Elastic
and Diffractive Scattering, Pruhonice, Czech Republic, 9-15 June 200
New measures of the quality and of the reliability of fits applied to forward hadronic data at t=0
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 200
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 . These indicators favor models with a universal
Pomeron term, which enables one to extend the fit down to GeV.Comment: 13 pages, COMPETE Collaboration, talk presented at the 9th
International Conference (Blois Workshop) on Elastic and Diffractive
Scatterin
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%.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, 200
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.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 200
Direct Calculations of the Odderon Intercept in the Perturbative QCD
The odderon intercept is calculated directly, from its expression via an
average energy of the odderon Hamiltonian, using both trial wave functions in
the variational approach and the wave function recently constructed by
R.A.Janik and J.Wosiek.
The results confirm their reported value for the energy. The odderon
intercept is calculated directly, from its expression via an average energy of
the odderon Hamiltonian, using both trial wave functions in the variational
approach and the wave function recently constructed by R.A.Janik and
J.Wosiek.The results confirm their reported value for the energy. Variational
calculations give energies some 30% higher. However they also predict the
odderon intercept to be quite close to unity. In fact, for realistic values of
, the intercept calculated variationally is at most 2% lower than the
exact one: 0.94 instead of 0.96. It is also found that the solution for
does not belong to the odderon spectrum. The diffusion parameter is found to be
of the order 0.6.Comment: 20 page
A New Method for the Determination of the Real Part of the Hadron Elastic Scattering Amplitude at Small Angles and High Energies
A new method for the determination of the real part of the elastic scattering
amplitude is examined for high energy proton-proton elastic scattering at small
momentum transfer. This method allows us to decrease the number of model
assumptions, to obtain the real part in a narrow region of momentum transfer
and to test different models. The real part is computed at a given point t_min
near t=0 from the known Coulomb amplitude. Hence one obtains an important
constraint on the real part of the forward scattering amplitude and therefore
on the rho-parameter (measuring the ratio of the real to imaginary part of the
scattering amplitude at t=0), which can be tested at LHC.Comment: 10 pages and 5 figures. Final published form in Physics Letters
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