Unitarity bound on the total cross section and forward slope of the deep inelastic ?N scattering amplitude

1979 ◽  
Vol 39 (2) ◽  
pp. 408-414
Author(s):  
I. Yu. Krivskii ◽  
Yu. A. Ksaverii
Keyword(s):  
Total Cross Section ◽  
Cross Section ◽  
Scattering Amplitude ◽  
Unitarity Bound

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.

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 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 SUPERCRITICAL POMERON AND EIKONAL REPRESENTATION OF THE DIFFRACTION SCATTERING AMPLITUDE

1995 ◽  
Vol 10 (26) ◽  
pp. 1959-1967
Author(s):  
S.V. GOLOSKOKOV ◽  
S.P. KULESHOV ◽  
O.V. SELYUGIN
Keyword(s):  
Experimental Data ◽  
Scattering Amplitudes ◽  
Total Cross Section ◽  
Cross Section ◽  
Scattering Amplitude ◽  
Diffraction Scattering ◽  
Eikonal Representation ◽  
The One ◽  
Qcd Pomeron ◽  
Logarithmic Growth

The intercept of the supercritical pomeron is examined with the use of different forms of the scattering amplitudes of the bare pomeron. The one-to-one correspondence between the eikonal phase and the ratio of the elastic and total cross-section is shown. Based on new experimental data of the CDF collaboration, the intercept and power of the logarithmic growth of the bare and total pomeron amplitude are analyzed. It is shown that as a result of the eikonalization procedure, the bare QCD pomeron becomes compatible with experiment.

Oscillatory Screening Effects on Elastic Collisions in Dense Electron-Ion Quantum Plasmas

2009 ◽  
Vol 64 (3-4) ◽  
pp. 237-241 ◽  
Author(s):  
Yo-Han Koo ◽  
Young-Dae Jung
Keyword(s):  
Phase Shift ◽  
Total Cross Section ◽  
Cross Section ◽  
Scattering Amplitude ◽  
Wave Number ◽  
Optical Theorem ◽  
Screening Effect ◽  
Quantum Plasmas ◽  
Quantum Wave ◽  
Scattering Phase

Abstract The oscillatory screening effects on elastic electron-ion collisions are investigated in dense quantum plasmas. The eikonal method with the modified Debye-Hückel potential is employed to obtain the scattering phase shift and scattering amplitude. In addition, the total elastic collision cross section is obtained by the optical theorem with the forward scattering amplitude in quantum plasmas. It is shown that the modified Debye-Hückel screening in quantum plasmas produces the oscillatory behaviour of the scattering phase shift. In addition, the minimum position of the phase shift is receded from the target ion with decreasing the quantum wave number. It is also found that the oscillatory screening effect suppresses the differential cross section. The total cross section is also found to be decreased due to the oscillatory screening effect. In addition, it is shown that the total cross section decreases with an increase of the quantum wave number

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