343 research outputs found
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
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 simple recipe to detect possible C-Odd effects in high energy and
We provide a theorem to suggest that data may already be sufficient to
detect possible asymptotic C-odd (Odderon) contributions. This can be done by
comparing and observables such as total cross sections,
forward angular distributions and ratios of real to imaginary forward
amplitudes for which well defined model independent correlations {must} exist
which could already show up at RHIC energy but definitely at LHC energies.Comment: 10 pages in TeX, no figur
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
Exploring power and knowledge in an educational documentary: a visual analysis of a film on the Benin bronzes
This research uses visual analysis to explore how an educational documentary portrays power and knowledge in the cultural sector. I examined a documentary I made about an exhibition of the Benin sculptures in 2007. Returning to it in 2018, I was surprised to find out how much the framing, lighting and composition of shots reveal about a museum's control of knowledge. The methodology is based on the visual analysis techniques described by Kress and van Leewen (1996).
The research draws on the theories of Foucault (1972), who argues that power and knowledge are inextricably linked, and relate to discourse: the way powerful institutions influence what is thinkable. Bennett (1995) developed Foucault's argument to suggest that museums, like schools and prisons, are weilders of power-knowledge and Said (2003) and Fanon (1997) have argued that Western academia is based on ideas brought back by early colonists about the colonised as subjects to be ruled
Nucleon Structure and High Energy Scattering
If the pomeron is generated by a two gluon exchange there is no a priori
reason for a drastic suppression of three gluon exchange with negative parity
and charge parity. This would lead to an unacceptably large difference between
and scattering. It is shown that a natural suppression of
the ==--1 contribution to high energy scattering is given by a cluster
structure of the nucleon.Comment: 10 pages, epsf.sty and a4wide.sty, 8 eps figs included complete
PS-file (with all figs) available at:
http://www.thphys.uni-heidelberg.de/~rueter
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
The Two-Component Non-Perturbative Pomeron and the G-Universality
In this communication we present a generalization of the Donnachie-Landshoff
model inspired by the recent discovery of a 2-component Pomeron in LLA-QCD by
Bartels, Lipatov and Vacca. In particular, we explore a new property, not
present in the usual Regge theory - the G-Universality - which signifies the
independence of one of the Pomeron components on the nature of the initial and
final hadrons. The best description of all the forward hadron-hadron, gamma-
gamma and gamma-proton data is obtained when G-universailty is imposed.
Moreover, the maximal (ln)**2 behaviour of the hadron amplitude, first
established by Heisenberg, is clearly favoured by the data.Comment: 5 pages, 2 tables, talk at the International Workshop on Diffraction
in High-Energy Physics "Diffraction 2000", Cetraro, Italy, September 2-7,
200
How can the Odderon be detected at RHIC and LHC
The Odderon remains an elusive object, 33 years after its invention. The
Odderon is now a fundamental object in QCD and CGC and it has to be found
experimentally if QCD and CGC are right. In the present paper, we show how to
find it at RHIC and LHC. The most spectacular signature of the Odderon is the
predicted difference between the differential cross-sections for proton-proton
and antiproton-proton at high s and moderate t. The experiment can be done by
using the STAR detector at RHIC and by combining these future data with the
already present UA4/2 data. The Odderon could also be found by ATLAS
exeperiment at LHC by performing a high-precision measurement of the real part
of the hadron elastic scattering amplitude at small t.Comment: 14 pages, 16 figures, two typographical errors corrected and
acknowledgments adde
Contrôle sismique d'un bâtiment en acier de 3 étages à l'échelle 1/3 par amortisseurs élastomères et contreventements en chevron
This study develops an innovative configuration of seismic natural rubber dampers for multistory low- and medium-rise steel braced frames. The dampers are directly integrated in an horizontal position in the seismic force resisting system of the structure. They are connected in a series with typical chevron brace systems.This control system provides not only additional structural damping to the structure but also a period shift, acting in the same way as a base isolation system. First, the fiber reinforced natural rubber used in the application was tested. It exhibited strong non linear dependance of its equivalent viscoelastic properties related to the shear strain. Then, a 1/3-scale 3-story chevron braced steel frame with and without dampers was considered. The structure was build and placed on the shaking table of the University of Sherbrooke Structures Laboratory. Numerical studies show that the efficiency of the control system reduces strongly the seismic induced forces of the undamped structure without any amplification of displacement or drift. Obtained seismic response reduction levels represent significant safety and economical benefits for the proposed application. Finally, the control system viability is experimentally demonstrated by shaking table tests at different reduced seismic intensities. Non linear behavior of the structure due to non linear behavior of the damping material is highlighted, and the dependance of seismic control performances is shown to be related to seismic intensities. Results allow an extrapolation of the experimental control peformances tending to the numerical results at higher intensities
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