Electromagnetic scattering by a perfectly conducting elliptic disk

1987 ◽  
Vol 65 (7) ◽  
pp. 723-734 ◽  
Author(s):  
Jonas Björkberg ◽  
Gerhard Kristensson
Keyword(s):  
Total Cross Section ◽  
Cross Section ◽  
Electromagnetic Scattering ◽  
Recurrence Relations ◽  
Scattering Amplitude ◽  
Azimuthal Angle ◽  
Low Frequency ◽  
Prolate Spheroid ◽  
Numerical Computations ◽  
Theoretical Results

Electromagnetic scattering from a perfectly conducting elliptic disk is treated by means of the null-field approach. The disk is obtained as the zero-thickness limit of an ellipsoid. It is shown that in this limit all relevant matrix elements have a well-defined limit. Owing to the lack of axial symmetry, an integral that can not be solved analytically remains in the azimuthal angle. In an appendix, an efficient algorithm to solve these integrals by means of recurrence relations is presented. The formalism is attractive for numerical computations, and stable results for very eccentric disks have been obtained. The first few terms in the low-frequency expansion of the total cross section are derived. Numerical computations of the scattering amplitude and the total cross section illustrate the theoretical results. In a final appendix, the thin wire limit of the elliptic disk is discussed, and a comparison with corresponding results of a prolate spheroid is presented.

scholarly journals First determination of the $${\rho }$$ parameter at $${\sqrt{s} = 13}$$ TeV: probing the existence of a colourless C-odd three-gluon compound state

2019 ◽  
Vol 79 (9) ◽  
Author(s):  
G. Antchev ◽  
P. Aspell ◽  
I. Atanassov ◽  
V. Avati ◽  
J. Baechler ◽  
...  
Keyword(s):  
Elastic Scattering ◽  
Total Cross Section ◽  
Cross Section ◽  
Scattering Amplitude ◽  
Theoretical Models ◽  
Proton Proton ◽  
Slowing Down ◽  
Proton Elastic Scattering ◽  
Compound State ◽  
Elastic Scattering Amplitude

Abstract The TOTEM experiment at the LHC has performed the first measurement at $$\sqrt{s} = 13\,\mathrm{TeV}$$s=13TeV of the $$\rho $$ρ parameter, the real to imaginary ratio of the nuclear elastic scattering amplitude at $$t=0$$t=0, obtaining the following results: $$\rho = 0.09 \pm 0.01$$ρ=0.09±0.01 and $$\rho = 0.10 \pm 0.01$$ρ=0.10±0.01, depending on different physics assumptions and mathematical modelling. The unprecedented precision of the $$\rho $$ρ measurement, combined with the TOTEM total cross-section measurements in an energy range larger than $$10\,\mathrm{TeV}$$10TeV (from 2.76 to $$13\,\mathrm{TeV}$$13TeV), has implied the exclusion of all the models classified and published by COMPETE. The $$\rho $$ρ results obtained by TOTEM are compatible with the predictions, from other theoretical models both in the Regge-like framework and in the QCD framework, of a crossing-odd colourless 3-gluon compound state exchange in the t-channel of the proton–proton elastic scattering. On the contrary, if shown that the crossing-odd 3-gluon compound state t-channel exchange is not of importance for the description of elastic scattering, the $$\rho $$ρ value determined by TOTEM would represent a first evidence of a slowing down of the total cross-section growth at higher energies. The very low-|t| reach allowed also to determine the absolute normalisation using the Coulomb amplitude for the first time at the LHC and obtain a new total proton–proton cross-section measurement $$\sigma _{\mathrm{tot}} = (110.3 \pm 3.5)\,\mathrm{mb}$$σtot=(110.3±3.5)mb, completely independent from the previous TOTEM determination. Combining the two TOTEM results yields $$\sigma _{\mathrm{tot}} = (110.5 \pm 2.4)\,\mathrm{mb}$$σtot=(110.5±2.4)mb.

2S Excitation of atomic hydrogen by electron impact at high energies

1983 ◽  
Vol 61 (5) ◽  
pp. 748-752 ◽  
Author(s):  
N. Saha
Keyword(s):  
Differential Cross Section ◽  
Total Cross Section ◽  
Electron Impact ◽  
Cross Section ◽  
Differential Cross ◽  
Atomic Hydrogen ◽  
Excitation Cross Section ◽  
High Energies ◽  
Comparison Of The Results ◽  
Theoretical Results

The 2S excitation cross section of atomic hydrogen by electron impact at high energies has been calculated following the method of Das. Comparison of the results for the differential cross section with other theoretical results, and comparison of the results for the total cross section with those of other theories and experiments, shows that the results of the present calculations are fairly accurate.

STUDY OF BFKL GLUON DYNAMICS IN HEAVY QUARKONIUM PHOTOPRODUCTION AT HERA

2000 ◽  
Vol 15 (10) ◽  
pp. 695-707 ◽  
Author(s):  
A. V. LIPATOV ◽  
N. P. ZOTOV
Keyword(s):  
Experimental Data ◽  
Total Cross Section ◽  
Cross Section ◽  
Gluon Distribution ◽  
Heavy Quarkonium ◽  
Unintegrated Gluon ◽  
Gluon Distributions ◽  
Theoretical Results

In the framework of semihard QCD approach we consider the processes of inelastic heavy quarkonium photoproduction at HERA with emphasis on the BFKL dynamics of gluon distributions. We investigate the dependences of the total cross-section of inelastic J/Ψ photoproduction and also pT and z spectra on different forms of the unintegrated gluon distribution. It is shown that the total cross-section is most sensitive to the Pomeron intercept parameter Δ. We compare the theoretical results with the available H1 and ZEUS experimental data.

scholarly journals ELASTIC SCATTERING OF PROTONS FROM $\sqrt{s} = 23.5~{\rm GeV}$ to 7 TeV FROM A GENERALIZED BIALAS–BZDAK MODEL

2014 ◽  
Vol 29 (02) ◽  
pp. 1450019 ◽  
Author(s):  
T. CSÖRGŐ ◽  
F. NEMES
Keyword(s):  
Elastic Scattering ◽  
Total Cross Section ◽  
Cross Section ◽  
Scattering Amplitude ◽  
Elastic Cross Section ◽  
Forward Scattering Amplitude ◽  
Proton Proton ◽  
Elastic Proton ◽  
Model Independent ◽  
Total P

The Bialas–Bzdak model of elastic proton–proton scattering is generalized to the case when the real part of the parton–parton level forward scattering amplitude is nonvanishing. Such a generalization enables the model to describe well the dip region of the differential cross-section of elastic scattering at the intersecting storage rings (ISR) energies, and improves significantly the ability of the model to describe also the recent TOTEM data at [Formula: see text] LHC energy. Within this framework, both the increase of the total cross-section, as well as the decrease of the location of the dip with increasing colliding energies, is related to the increase of the quark–diquark distance and to the increase of the "fragility" of the protons with increasing energies. In addition, we present and test the validity of two new phenomenological relations: one of them relates the total p+p cross-section to an effective, model-independent proton radius, while the other relates the position of the dip in the differential elastic cross-section to the measured value of the total cross-section.

Electron Excitation of 21S, 23S, 21P, and 23P States of Helium

1975 ◽  
Vol 53 (20) ◽  
pp. 2289-2295 ◽  
Author(s):  
H. G. P. Lins de Barros ◽  
H. S. Brandi
Keyword(s):  
Total Cross Section ◽  
Cross Section ◽  
Cross Sections ◽  
Scattering Amplitude ◽  
Theoretical Calculations ◽  
Electron Excitation ◽  
Wave Functions ◽  
Excitation Cross Sections ◽  
Characteristic Values ◽  
The One

Calculations for the total excitation cross sections of the 21S, 23S, 21P, and 23P states of He by electron impact have been carried out assuming the Born–Ochkur approximation for the scattering amplitude and a parametrization previously proposed by the authors for the total cross section. For the atomic wave functions we used LS coupling and obtained the one electron orbitals using the Xα method for three characteristic values of the parameter α. The results are compared with other experimental and theoretical calculations.

scholarly journals A Tutorial on the Classical Theories of Electromagnetic Scattering and Diffraction

Nanophotonics ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 315-342
Author(s):  
Masud Mansuripur
Keyword(s):  
Cross Section ◽  
Electromagnetic Scattering ◽  
Final Section ◽  
Scattering Amplitude ◽  
Plane Waves ◽  
Homogeneous Medium ◽  
Far Field ◽  
Scalar Diffraction ◽  
Optical Cross Section ◽  
Section Theorem

AbstractStarting with Maxwell’s equations, we derive the fundamental results of the Huygens-Fresnel-Kirchhoff and Rayleigh-Sommerfeld theories of scalar diffraction and scattering. These results are then extended to cover the case of vector electromagnetic fields. The famous Sommerfeld solution to the problem of diffraction from a perfectly conducting half-plane is elaborated. Far-field scattering of plane waves from obstacles is treated in some detail, and the well-known optical cross-section theorem, which relates the scattering cross-section of an obstacle to its forward scattering amplitude, is derived. Also examined is the case of scattering from mild inhomogeneities within an otherwise homogeneous medium, where, in the first Born approximation, a fairly simple formula is found to relate the far-field scattering amplitude to the host medium’s optical properties. The related problem of neutron scattering from ferromagnetic materials is treated in the final section of the paper.

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