scholarly journals COHERENT PAIR PRODUCTION IN DEFORMED CRYSTALS WITH A COMPLEX BASE

2006 ◽  
Vol 20 (25) ◽  
pp. 1617-1627 ◽  
Author(s):  
A. R. MKRTCHYAN ◽  
A. A. SAHARIAN ◽  
V. V. PARAZIAN
Keyword(s):  
Differential Cross Section ◽  
Single Crystal ◽  
Cross Section ◽  
High Energy ◽  
Pair Creation ◽  
Deformation Field ◽  
Crystallographic Axis ◽  
Electron Positron ◽  
Coherent Pair ◽  
Electron Positron Pair

We investigate the coherent electron–positron pair creation by high-energy photons in a periodically deformed single crystal with a complex base. The formula for the corresponding differential cross-section is derived for an arbitrary deformation field. The conditions are specified under which the influence of the deformation is considerable. The case is considered in detail when the photon enters into the crystal at small angles with respect to a crystallographic axis. The results of the numerical calculations are presented for SiO 2 single crystal and Moliere parametrization of the screened atomic potentials in the case of the deformation field generated by the acoustic wave of S type. In dependence of the parameters, the presence of deformation can either enhance or reduce the pair creation cross-section. This can be used to control the parameters of the positron sources for storage rings and colliders.

COHERENT PAIR PRODUCTION IN CRYSTALS IN PRESENCE OF ACOUSTIC WAVES

2010 ◽  
Vol 25 (supp01) ◽  
pp. 47-54
Author(s):  
A. R. MKRTCHYAN ◽  
A. A. SAHARIAN ◽  
V. V. PARAZIAN
Keyword(s):  
Single Crystal ◽  
Pair Production ◽  
Cross Section ◽  
Acoustic Waves ◽  
High Energy ◽  
Deformation Field ◽  
Crystallographic Axis ◽  
Electron Positron ◽  
Coherent Pair ◽  
Electron Positron Pair

Coherent electron-positron pair production by high-energy photons is investigated in a periodically deformed single crystal with a complex base. The formula for the corresponding differential cross-section is derived for an arbitrary deformation field. The conditions are specified under which the influence of the deformation is considerable. The case is considered in detail when the photon enters into the crystal at small angles with respect to a crystallographic axis. The results of the numerical calculations are presented for SiO 2 single crystal in the case of the deformation field generated by the acoustic wave of the S type. It is shown that, in dependence of the parameters, the presence of deformation can either enhance or reduce the pair creation cross-section.

scholarly journals ON THE THEORY OF COHERENT PAIR PRODUCTION IN CRYSTALS IN THE PRESENCE OF ACOUSTIC WAVES

2002 ◽  
Vol 17 (39) ◽  
pp. 2571-2580 ◽  
Author(s):  
A. R. MKRTCHYAN ◽  
A. A. SAHARIAN ◽  
L. SH. GRIGORYAN ◽  
B. V. KHACHATRYAN
Keyword(s):  
Differential Cross Section ◽  
Cross Section ◽  
Acoustic Waves ◽  
High Energy ◽  
Pair Creation ◽  
Wave Number ◽  
Electron Positron ◽  
Coherent Pair ◽  
Electron Positron Pair ◽  
Coherent Part

The influence of hypersonic waves excited in a single crystal is investigated on the process of electron–positron pair creation by high-energy photons. The coherent part of the corresponding differential cross-section is derived as a function of the amplitude and wave number of the hypersound. The values of the parameters are specified for which the latter affects remarkably on the pair creation cross-section. It is shown that under certain conditions the presence of hypersonic waves can result in enhancement of the process cross-section.

scholarly journals COHERENT BREMSSTRAHLUNG IN PERIODICALLY DEFORMED CRYSTALS WITH A COMPLEX BASE

2009 ◽  
Vol 23 (20n21) ◽  
pp. 2573-2584 ◽  
Author(s):  
A. R. MKRTCHYAN ◽  
A. A. SAHARIAN ◽  
V. V. PARAZIAN
Keyword(s):  
Differential Cross Section ◽  
Single Crystal ◽  
Cross Section ◽  
Differential Cross ◽  
High Energy ◽  
Deformation Field ◽  
Crystallographic Axis ◽  
High Energy Electrons ◽  
Coherent Bremsstrahlung

In the present paper, we investigate coherent bremsstrahlung of high energy electrons moving in a periodically deformed single crystal with a complex base. The formula for corresponding differential cross-section is derived for an arbitrary deformation field. The conditions are discussed under which the influence of the deformation is important. The case is considered in detail when the electron enters into the crystal at small angles with respect to a crystallographic axis. It is shown that in dependence of the parameters, the presence of the deformation can either enhance or reduce the bremsstrahlung cross-section.

scholarly journals ON THE INFLUENCE OF ACOUSTIC WAVES ON COHERENT BREMSSTRAHLUNG IN CRYSTALS

2004 ◽  
Vol 19 (02) ◽  
pp. 99-109 ◽  
Author(s):  
A. A. SAHARIAN ◽  
A. R. MKRTCHYAN ◽  
V. V. PARAZIAN ◽  
L. SH. GRIGORYAN
Keyword(s):  
Differential Cross Section ◽  
Single Crystal ◽  
Cross Section ◽  
Differential Cross ◽  
Acoustic Waves ◽  
Crystallographic Axis ◽  
Relativistic Electrons ◽  
Sinusoidal Wave ◽  
Coherent Bremsstrahlung

We investigate the coherent bremsstrahlung by relativistic electrons in a single crystal excited by hypersonic vibrations. The formula for the corresponding differential cross-section is derived in the case of a sinusoidal wave. The conditions are specified under which the influence of the hypersound is essential. The case is considered in detail when the electron enters into the crystal at small angles with respect to a crystallographic axis. It is shown that in dependence of the parameters, the presence of hypersonic waves can either enhance or reduce the bremsstrahlung cross-section.

Vector meson production in electron positron annihilation process

2021 ◽  
pp. 2150120
Author(s):  
Weihua Yang ◽  
Fei Huang
Keyword(s):  
Differential Cross Section ◽  
Vector Meson ◽  
Positron Annihilation ◽  
Cross Section ◽  
Differential Cross ◽  
High Energy ◽  
Annihilation Process ◽  
Electron Positron Annihilation ◽  
Electron Positron ◽  
Fragmentation Functions

When tunneling events induced by nontrivial configurations of the quantum chromodynamics gauge fields are taken into consideration, parity violating quantities emerge. Based on this consideration, parity-odd fragmentation functions can be introduced in the high energy reactions. In this paper, we calculate the differential cross-section in terms of both the parity-even and parity-odd fragmentation functions in semi-inclusive electron positron annihilation process. Semi-inclusive implies that not only a vector meson in one jet but also the back-to-back jet is measured in this reaction. According to the differential cross-section, we further calculate the azimuthal asymmetries and hadron polarizations in terms of fragmentation functions. A method of measuring the parity violating effects in the semi-inclusive annihilation process is suggested.

Vacuum polarization and particle creation in the presence of a potential step

2016 ◽  
Vol 31 (02n03) ◽  
pp. 1641031 ◽  
Author(s):  
S. P. Gavrilov ◽  
D. M. Gitman
Keyword(s):  
Electric Potential ◽  
Canonical Quantization ◽  
Particle Creation ◽  
Pair Creation ◽  
Dirac Field ◽  
Potential Step ◽  
Electron Positron ◽  
Physical Impact ◽  
Particle Interpretation ◽  
Electron Positron Pair

We consider QED with strong external backgrounds that are concentrated in restricted space areas. The latter backgrounds represent a kind of spatial x-electric potential steps for charged particles. They can create particles from the vacuum, the Klein paradox being closely related to this process. We describe a canonical quantization of the Dirac field with x-electric potential step in terms of adequate in- and out-creation and annihilation operators that allow one to have consistent particle interpretation of the physical system under consideration and develop a nonperturbative (in the external field) technics to calculate scattering, reflection, and electron-positron pair creation. We resume the physical impact of this development.

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