scholarly journals AGK CUTTING RULES AND PERTURBATIVE QCD

1996 ◽  
Vol 11 (04) ◽  
pp. 613-654 ◽  
Author(s):  
D. TRELEANI
Keyword(s):  
Perturbative Qcd ◽  
Cross Section ◽  
Cross Sections ◽  
Parton Model ◽  
Single Scattering ◽  
High Energy ◽  
The Self ◽  
Energy Hadron ◽  
Three Body ◽  
Soft Interactions

The purpose of this article is to describe a few features of semihard interactions, in high energy nuclear collisions, that are better understood with the help of the AGK cutting rules, and of the probabilistic picture of the interaction which follows. In the first part of the article the cutting rules are discussed for the simplest component of the forward three-body parton amplitude in the large s fixed t limit. The case considered corresponds to the term — at the lowest order in the coupling constant and with vacuum quantum number exchange in both t channels — of the amplitude which describes the interaction of a high energy quark with the two target quarks. The different leading cuts of the amplitude are shown to be proportional to one another with the same weights of the cutting rules derived in the context of multi-Pomeron exchange. The probabilistic picture of the multiple interactions, which originates from the cutting rules, and the self-shadowing cross sections are then discussed. The second part of the article deals with the semihard interactions. The semihard cross section in high energy nucleus–nucleus collisions is represented as a self-shadowing cross section, and a feature which is pointed out is that the single scattering factorized expression of the perturbative QCD parton model holds at any order in the multiparton correlations, the relation being the analog of the AGK cancellation for the average number of soft interactions in high energy hadron–nucleus collisions. Finally, an infrared problem which finds a solution within the self-shadowing representation of the semihard cross section is discussed.

scholarly journals Hadron wave functions in high-energy scattering, form factors and strong decays: The effects of the Lorentz contracted form

2021 ◽  
Vol 36 (37) ◽  
Author(s):  
Yu. A. Simonov
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Lorentz Invariance ◽  
Form Factors ◽  
High Energy ◽  
Wave Functions ◽  
Large Momentum ◽  
Momentum Dependence ◽  
Lorentz Contraction ◽  
Energy Hadron

In this paper, we study the class of the processes, where dynamics depends essentially on the properties of the hadron wave functions involved in the reactions. In this case, the momentum dependence of the form of the wave functions, imposed by the Lorentz invariance and in particular by the Lorentz contraction, can be tested in the experiment and may strongly influence the resulting cross-sections. One example of such observables is given by the hadron form factors in the case when the large [Formula: see text] behavior is mostly frozen, while the Lorentz contraction of the hadron wave functions is taken into account. Another example, considered earlier, is the strong hadron decay with high-energy emission. In this paper, we study the role of the Lorentz contraction in the high-energy hadron–hadron scattering process at large momentum transfer. For the [Formula: see text] and [Formula: see text] scattering at large [Formula: see text], it is shown that at small [Formula: see text], the picture of two exponential slopes in the differential cross-section, explained previously by the author, remains stable, while the backward scattering cross-section is strongly increased by the Lorentz contraction.

scholarly journals On the role of longitudinal momenta in high energy hadron-hadron scattering

Open Physics ◽  
2012 ◽  
Vol 10 (4) ◽  
Author(s):  
Igor Sharf ◽  
Andrii Tykhonov ◽  
Grygorii Sokhrannyi ◽  
Maksym Deliyergiyev ◽  
Natalia Podolyan ◽  
...  
Keyword(s):  
Inelastic Scattering ◽  
Cross Section ◽  
Cross Sections ◽  
High Energy ◽  
Momentum Conservation ◽  
Scattering Cross ◽  
Energy Hadron ◽  
Scattering Cross Sections ◽  
Energy Momentum Conservation

AbstractWe demonstrate a new method to calculate inelastic scattering cross-sections, which in contrary to the Regge-based methods takes into account the energy momentum conservation law. It is shown that the main contribution to integral expressing inelastic scattering cross-sections does not come from the multi-Regge domain. In particular, accounting for the longitudinal momenta contribution to virtualities is sufficient and results in the new mechanism of cross-section growth. The reasons for taking into account the sufficiently high number of interference contributions are shown and the approximate method for this purpose is developed. By fitting single free parameter of the model achieved a qualitative agreement of the total and inelastic cross sections with experimental data.

A possible pomeron building mechanism in the fragmentation region

1978 ◽  
Vol 56 (9) ◽  
pp. 1142-1149
Author(s):  
C. G. Georgalas ◽  
P. H. Papargyropoulos
Keyword(s):  
Integral Equation ◽  
Cross Section ◽  
Cross Sections ◽  
Inclusive Cross Section ◽  
High Energy ◽  
Fragmentation Region ◽  
Total Cross Sections ◽  
Energy Hadron ◽  
The One ◽  
Good Agreement

By the use of a Regge parametrization of the one-particle inclusive cross section in the fragmentation region, an integral equation is obtained for the high-energy hadron–hadron inelastic cross section. The main assumptions used in the derivation of this integral equation are: (i) When two hadrons collide with sufficiently high energy, the elastic, inelastic, and total cross sections have the same energy dependence and (ii) Unitarity and factorization of Regge residues hold also for Reggeon–hadron 'amplitudes'. The solution of the integral equation, i.e., the function σinel(s) can be made constant or slowly increasing. For 'reasonable' values of all the parameters involved, it is in very good agreement with the high energy pp data.

scholarly journals Total cross sections of eγ → $$ eX\overline{X} $$ processes with X = μ, γ, e via multiloop methods

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Roman N. Lee ◽  
Alexey A. Lyubyakin ◽  
Vyacheslav A. Stotsky
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Elliptic Integral ◽  
High Energy ◽  
Calculation Methods ◽  
Complete Elliptic Integral ◽  
Total Cross Sections ◽  
Multiloop Calculation ◽  
The Cross ◽  
Analytical Expressions

Abstract Using modern multiloop calculation methods, we derive the analytical expressions for the total cross sections of the processes e−γ →$$ {e}^{-}X\overline{X} $$ e − X X ¯ with X = μ, γ or e at arbitrary energies. For the first two processes our results are expressed via classical polylogarithms. The cross section of e−γ → e−e−e+ is represented as a one-fold integral of complete elliptic integral K and logarithms. Using our results, we calculate the threshold and high-energy asymptotics and compare them with available results.

scholarly journals Saturation effects in SIDIS at very forward rapidities

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
E. Iancu ◽  
A. H. Mueller ◽  
D. N. Triantafyllopoulos ◽  
S. Y. Wei
Keyword(s):  
Inelastic Scattering ◽  
Cross Section ◽  
Cross Sections ◽  
Virtual Photon ◽  
Large Fraction ◽  
Quark Distribution ◽  
High Energy ◽  
Longitudinal Momentum ◽  
Black Disk ◽  
Gluon Saturation

Abstract Using the dipole picture for electron-nucleus deep inelastic scattering at small Bjorken x, we study the effects of gluon saturation in the nuclear target on the cross-section for SIDIS (single inclusive hadron, or jet, production). We argue that the sensitivity of this process to gluon saturation can be enhanced by tagging on a hadron (or jet) which carries a large fraction z ≃ 1 of the longitudinal momentum of the virtual photon. This opens the possibility to study gluon saturation in relatively hard processes, where the virtuality Q2 is (much) larger than the target saturation momentum $$ {Q}_s^2 $$ Q s 2 , but such that z(1 − z)Q2 ≲ $$ {Q}_s^2 $$ Q s 2 . Working in the limit z(1 − z)Q2 ≪ $$ {Q}_s^2 $$ Q s 2 , we predict new phenomena which would signal saturation in the SIDIS cross-section. For sufficiently low transverse momenta k⊥ ≪ Qs of the produced particle, the dominant contribution comes from elastic scattering in the black disk limit, which exposes the unintegrated quark distribution in the virtual photon. For larger momenta k⊥ ≳ Qs, inelastic collisions take the leading role. They explore gluon saturation via multiple scattering, leading to a Gaussian distribution in k⊥ centred around Qs. When z(1 − z)Q2 ≪ Q2, this results in a Cronin peak in the nuclear modification factor (the RpA ratio) at moderate values of x. With decreasing x, this peak is washed out by the high-energy evolution and replaced by nuclear suppression (RpA< 1) up to large momenta k⊥ ≫ Qs. Still for z(1 − z)Q2 ≪ $$ {Q}_s^2 $$ Q s 2 , we also compute SIDIS cross-sections integrated over k⊥. We find that both elastic and inelastic scattering are controlled by the black disk limit, so they yield similar contributions, of zeroth order in the QCD coupling.

INELASTIC PHOTOPRODUCTION OF W-BOSON

1998 ◽  
Vol 13 (25) ◽  
pp. 2013-2020
Author(s):  
S. M. KHAIRUL ALAM ◽  
A. M. HARUN AR RASHID
Keyword(s):  
Differential Cross Section ◽  
Cross Section ◽  
W Boson ◽  
Electric Quadrupole ◽  
Parton Model ◽  
High Energy ◽  
Electric Quadrupole Moment ◽  
Photoproduction Process ◽  
Quark Parton Model ◽  
High Energy Collider

We study the WWγ vertex through the process γq→Wq′ where q denotes the quark at a future high energy collider. The differential cross-section for the photoproduction process γq→Wq′ is computed with both anomalous magnetic moment κ and electric quadrupole moment λ for the W-boson. The deep inelastic photoproduction of W± is also calculated in a quark-parton model.

scholarly journals Study of the 232Th(n,f) Cross section at NCSR ‘Demokritos’ using Micromegas Detectors

2020 ◽  
Vol 27 ◽  
pp. 106
Author(s):  
Sotirios Chasapoglou ◽  
A. Tsantiri ◽  
A. Kalamara ◽  
M. Kokkoris ◽  
V. Michalopoulou ◽  
...  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Nuclear Reactions ◽  
Detection Efficiency ◽  
High Energy ◽  
Tandem Accelerator ◽  
Line Detector ◽  
Accelerator Driven Systems ◽  
The Masses

The accurate knowledge of neutron-induced fission cross sections in actinides, is of great importance when it comes to the design of fast nuclear reactors, as well as accelerator driven systems. Specifically for the 232Th(n,f) case, the existing experimental datasets are quite discrepant in both the low and high energy MeV regions, thus leading to poor evaluations, a fact that in turn implies the need for more accurate measurements.In the present work, the total cross section of the 232Th(n,f) reaction has been measured relative to the 235U(n,f) and 238U(n,f) ones, at incident energies of 7.2, 8.4, 9.9 MeV and 14.8, 16.5, 17.8 MeV utilizing the 2H(d,n) and 3H(d,n) reactions respectively, which generally yield quasi-monoenergetic neutron beams. The experiments were performed at the 5.5 MV Tandem accelerator laboratory of N.C.S.R. “Demokritos”, using a Micromegas detector assembly and an ultra thin ThO2 target, especially prepared for fission measurements at n_ToF, CERN during its first phase of operations, using the painting technique. The masses of all actinide samples were determined via α-spectroscopy. The produced fission yields along with the results obtained from activation foils were studied in parallel, using both the NeusDesc [1] and MCNP5 [2] codes, taking into consideration competing nuclear reactions (e.g. deuteron break up), along with neutron elastic and inelastic scattering with the beam line, detector housing and experimental hall materials. Since the 232Th(n,f) reaction has a relatively low energy threshold and can thus be affected by parasitic neutrons originating from a variety of sources, the thorough characterization of the neutron flux impinging on the targets is a prerequisite for accurate cross-section measurements, especially in the absence of time-of-flight capabilities. Additional Monte-Carlo simulations were also performed coupling both GEF [3] and FLUKA [4] codes for the determination of the detection efficiency.

Measurements of Displacement Cross Section of Tungsten under 389-MeV Proton Irradiation and Thermal Damage Recovery

2021 ◽  
Vol 1024 ◽  
pp. 95-101
Author(s):  
Yosuke Iwamoto ◽  
Makoto Yoshida ◽  
Hiroki Matsuda ◽  
Shin Ichiro Meigo ◽  
Daiki Satoh ◽  
...  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Thermal Conduction ◽  
Thermal Damage ◽  
Proton Irradiation ◽  
High Energy ◽  
Wire Sample ◽  
Energy Proton ◽  
Measured Displacement ◽  
Mev Protons

For validating the number of displacements per atom (dpa) for tungsten under high-energy proton irradiation, we measured displacement cross sections related to defect-induced electrical resistivity changes in a tungsten wire sample under irradiation with 389-MeV protons under 10 K. The Gifford–McMahon cryocooler was used to cool the sample using a conductive coolant via thermal conduction plates of oxygen-free high-conductivity copper and electrical insulation sheets of aluminum nitride ceramic. In this experiment, the displacement cross section was 1612 ± 371 b for tungsten at 389 MeV. A comparison of the experimental displacement cross sections of tungsten with the calculated results obtained using Norgett–Robinson–Torrens (NRT) dpa and athermal recombination-corrected (arc) dpa cross sections indicates that arc-dpa was in better agreement with the experimental data than NRT-dpa; this is similar to the displacement cross sections of copper. From the measurements of damage recovery of the accumulated defects in tungsten through isochronal annealing, which is related to the defect concentration of the sample, approximately 20% of the damage was recovered at 60 K. This trend was similar to those observed in other experimental results for reactor neutrons.

Note on the production of positron-electron pairs during the passage of β-particles through matter

1938 ◽  
Vol 34 (3) ◽  
pp. 435-441 ◽  
Author(s):  
N. Feather ◽  
J. V. Dunworth
Keyword(s):  
Cross Section ◽  
Atomic Number ◽  
Cross Sections ◽  
High Energy ◽  
Coincidence Counting ◽  
Electron Pairs ◽  
Radioactive Substances

The method of coincidence counting has been applied to an investigation of the possible production of positron-electron pairs by the high energy β-particles from a source of uranium X in absorbers of aluminium, brass and lead. The results are not inconsistent with the high values recently reported for atomic cross-sections for the effect, nor with the suggestion that the atomic cross-section is proportional to the first power of the atomic number rather than the second. Suggestions are made for the use of the β-particles from artificially radioactive substances in an attempt to increase the sensitivity of the method.

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