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.

scholarly journals Experimental Review of ΛΛ¯ Production

Symmetry ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 144
Author(s):  
Xiaorong Zhou ◽  
Liang Yan ◽  
Rinaldo Baldini Ferroli ◽  
Guangshun Huang
Keyword(s):  
Positron Annihilation ◽  
Cross Section ◽  
Production Cross ◽  
High Energy ◽  
Threshold Region ◽  
Initial State ◽  
Precision Data ◽  
Electron Positron Annihilation ◽  
Electron Positron ◽  
State Radiation

Exclusive hyperon-antihyperon production provides a unique insight for understanding of the intrinsic dynamics when strangeness is involved. In this paper, we review the results of ΛΛ¯ production via different reactions from various experiments, e.g., via p¯p annihilation from the LEAR experiment PS185, via electron-positron annihilation using the energy scan method at the CLEO-c and BESIII experiments and the initial-state-radiation approach utilized at the BaBar experiment. The production cross section of ΛΛ¯ near the threshold is sensitive to QCD based prediction. Experimental high precision data for p¯p→Λ¯Λ close to the threshold region is obtained. The cross section of e+e−→ΛΛ¯ is measured from its production threshold to high energy. A non-zero cross section for e+e−→ΛΛ¯ near threshold is observed at BaBar and BESIII, which is in disagreement with the pQCD prediction. However, more precise data is needed to confirm this observation. Future experiments, utilizing p¯p reaction such as PANDA experiment or electron-positron annihilation such as the BESIII and BelleII experiments, are needed to extend the experimental data and to understand the ΛΛ¯ production.

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.

Resonant production of electron-positron pairs by a hard gamma-ray on a nucleus in an external electromagnetic field

2020 ◽  
Vol 35 (03) ◽  
pp. 2040025 ◽  
Author(s):  
Nikita R. Larin ◽  
Victor V. Dubov ◽  
Sergei P. Roshchupkin
Keyword(s):  
Electromagnetic Field ◽  
Differential Cross Section ◽  
External Field ◽  
Cross Section ◽  
Differential Cross ◽  
Gamma Ray ◽  
Structure Constant ◽  
External Electromagnetic Field ◽  
Electron Positron ◽  
Resonant Production

The resonant production of electron-positron pairs by a hard gamma-ray on nucleus in an external electromagnetic field is studied theoretically. The main property of this process is that the initial process of the second order in the fine structure constant in an external field effectively splits into two successive processes of the first order due to the fact that in resonant conditions intermediate virtual electron (positron) becomes a real particle. One of these processes is a single-photoproduction of electron-positron pair in a laser field (laser-stimulated Breit-Wheeler process) another is a laser-assisted scattering of electron (positron) on nucleus (laser-assisted Mott scattering). It is shown that the resonances are possible only for the energies of the initial hard gamma-ray more than the characteristic threshold energy. Resonant differential cross section of this process is obtained. It is shown that the resonant differential cross section can significantly exceed the corresponding cross section without an external field. The obtained results may be experimentally verified using the facilities of pulsed laser radiation (SLAC, FAIR, XFEL, ELI, XCELS).

THE FORWARD PEAK OF ELASTIC HARDON-HADRON SCATTERING AND UNITARITY BOUNDS FOR THE DIFFERENTIAL CROSS-SECTION

1992 ◽  
Vol 07 (21) ◽  
pp. 1905-1913 ◽  
Author(s):  
M. KAWASAKI ◽  
T. MAEHARA ◽  
M. YONEZAWA
Keyword(s):  
Differential Cross Section ◽  
Cross Section ◽  
Differential Cross ◽  
Scattering Amplitude ◽  
High Energy ◽  
Forward Peak ◽  
Forward Scattering Amplitude ◽  
Interaction Radius ◽  
Interaction Range ◽  
Small Momentum

Unitarity bounds for the differential cross-section of high-energy elastic hadron-hadron scattering are obtained under the constraints of fixed total cross-section σt, elasticity x, real part to imaginary part ratio ρ of the forward scattering amplitude, and forward slope b by assuming a finite interaction range. The obtained upper bound has an observed curvature structure at small momentum transfers and is nearly saturated by the experimental data of pp and [Formula: see text] scattering at −t=0−0.3 (GeV/c)2 in the energy region [Formula: see text] , if we take the interaction radius scaled as [Formula: see text].

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