72 research outputs found
Hadronic sizes and observables in high-energy scattering
The functional dependence of the high-energy observables of total cross
section and slope parameter on the sizes of the colliding hadrons predicted by
the model of the stochastic vacuum and the corresponding relations used in the
geometric model of Povh and H\"ufner are confronted with the experimental data.
The existence of a universal term in the expression for the slope, due purely
to vacuum effects, independent of the energy and of the particular hadronic
system, is investigated. Accounting for the two independent correlation
functions of the QCD vacuum, we improve the simple and consistent description
given by the model of the stochastic vacuum to the high-energy pp and pbar-p
data, with a new determination of parameters of non-perturbative QCD. The
increase of the hadronic radii with the energy accounts for the energy
dependence of the observables.Comment: Latex, using Revtex.style . 2 ps figures. To be published in Physical
Review D , July 199
Participation in Hackathons:A Multi-Methods View on Motivators, Demotivators and Citizen Participation
Non-Perturbative QCD Treatment of High-Energy Hadron-Hadron Scattering
Total cross-sections and logarithmic slopes of the elastic scattering
cross-sections for different hadronic processes are calculated in the framework
of the model of the stochastic vacuum. The relevant parameters of this model, a
correlation length and the gluon condensate, are determined from scattering
data, and found to be in very good agreement with values coming from completely
different sources of information. A parameter-free relation is given between
total cross-sections and slope parameters, which is shown to be remarkably
valid up to the highest energies for which data exist.Comment: 60 pages, Heidelberg preprin
Scaling violations: Connections between elastic and inelastic hadron scattering in a geometrical approach
Starting from a short range expansion of the inelastic overlap function,
capable of describing quite well the elastic pp and scattering data,
we obtain extensions to the inelastic channel, through unitarity and an impact
parameter approach. Based on geometrical arguments we infer some
characteristics of the elementary hadronic process and this allows an excellent
description of the inclusive multiplicity distributions in and
collisions. With this approach we quantitatively correlate the violations of
both geometrical and KNO scaling in an analytical way. The physical picture
from both channels is that the geometrical evolution of the hadronic
constituents is principally reponsible for the energy dependence of the
physical quantities rather than the dynamical (elementary) interaction itself.Comment: 16 pages, aps-revtex, 11 figure
QCD Corrections to QED Vacuum Polarization
We compute QCD corrections to QED calculations for vacuum polarization in
background magnetic fields. Formally, the diagram for virtual loops
is identical to the one for virtual loops. However due to
confinement, or to the growth of as decreases, a direct
calculation of the diagram is not allowed. At large we consider the
virtual diagram, in the intermediate region we discuss the role of
the contribution of quark condensates \left and at the
low-energy limit we consider the , as well as charged pion
loops. Although these effects seem to be out of the measurement accuracy of
photon-photon laboratory experiments they may be relevant for -ray
burst propagation. In particular, for emissions from the center of the galaxy
(8.5 kpc), we show that the mixing between the neutral pseudo-scalar pion
and photons renders a deviation from the power-law spectrum in the
range. As for scalar quark condensates \left and
virtual loops are relevant only for very high radiation density
and very strong magnetic fields of order .Comment: 15 pages, 4 figures; Final versio
Occurrence of Mansonella ozzardi diagnosed using a polycarbonate membrane in a riverside population of Lábrea in the Western Brazilian Amazon
Bovine Pulp Tissue Dissolution Ability of Irrigants Associated or Not to Ultrasonic Agitation
Evaluation of the physicochemical properties of silicone- and epoxy resin-based root canal sealers
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