84 research outputs found
High-Energy Forward Scattering and the Pomeron: Simple Pole versus Unitarized Models
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 adde
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.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, I
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
The effect of hypoxia on photocytotoxicity of tics tricaebocyanine dye in vitro
To evaluate the effect of cell oxygenation on photocytotoxicity of a novel tricarbocyanine indolenine dye covalently bound to glucose (TICS). Methods: HeLa cells were incubated with 5 µM TICS, 2 h later irradiated by laser at 740 nm with a light dose of
10 J/cm2, delivered at a power density of 10, 20, 25 or 30 mW/cm2, in air or in argon atmosphere, and then scored for viability. Results: The photocytotoxicity of TICS increased dramatically as the power density was reduced. Under hypoxia TICS-photosensitized cell death was determined but its value was lowered, compared to photoirradiation in the air. Conclusion: Photosensitizing
effect of TICS is only partially dependent on the oxygenation of tumor cells
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
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
P-P Total Cross Sections at VHE from Accelerator Data
Comparison of P-P total cross-sections estimations at very high energies -
from accelerators and cosmic rays - shows a disagreement amounting to more than
10 %, a discrepancy which is beyond statistical errors. Here we use a
phenomenological model based on the Multiple-Diffraction approach to
successfully describe data at accelerator energies. The predictions of the
model are compared with data On the basis of regression analysis we determine
confident error bands, analyzing the sensitivity of our predictions to the
employed data for extrapolation. : using data at 546 and 1.8 TeV, our
extrapolations for p-p total cross-sections are only compatible with the Akeno
cosmic ray data, predicting a slower rise with energy than other cosmic ray
results and other extrapolation methods. We discuss our results within the
context of constraints in the light of future accelerator and cosmic ray
experimental results.Comment: 26 pages aqnd 11 figure
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%.Comment: 11 pages, 2 figures, 4 tables, RevTeX
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