scholarly journals Charged Particles Multiplicity and Scaling Violation of Fragmentation Functions in Electron-Positron Annihilation

2016 ◽  
Vol 2016 ◽  
pp. 1-8
Author(s):  
Tooraj Ghaffary
Keyword(s):  
Center Of Mass ◽  
Charged Particles ◽  
Splitting Function ◽  
Annihilation Process ◽  
Center Of Mass Energy ◽  
Electron Positron Annihilation ◽  
Electron Positron ◽  
Momentum Spectra ◽  
Fragmentation Functions ◽  
Scaling Violations

By the use of data from the annihilation process of electron-positron in AMY detector at 60 GeV center of mass energy, charged particles multiplicity distribution is obtained and fitted with the KNO scaling. Then, momentum spectra of charged particles and momentum distribution with respect to the jet axis are obtained, and the results are compared to the different models of QCD; also, the distribution of fragmentation functions and scaling violations are studied. It is being expected that the scaling violations of the fragmentation functions of gluon jets are stronger than the quark ones. One of the reasons for such case is that splitting function of quarks is larger than splitting function of gluon.

Hadron Production by Electron-Positron Annihilation at 4-GeV Center-of-Mass Energy

1973 ◽  
Vol 30 (23) ◽  
pp. 1189-1192 ◽  
Author(s):  
A. Litke ◽  
G. Hanson ◽  
A. Hofmann ◽  
J. Koch ◽  
L. Law ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Center Of Mass ◽  
Hadron Production ◽  
Mass Energy ◽  
Center Of Mass Energy ◽  
Electron Positron Annihilation ◽  
Electron Positron

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.

Hadron Production by Electron-Positron Annihilation at 4-GeV Center- of-Mass Energy.

1973 ◽  
Vol 30 (26) ◽  
pp. 1349-1349 ◽  
Author(s):  
A. Litke ◽  
G. Hanson ◽  
A. Hofmann ◽  
J. Koch ◽  
L. Law ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Center Of Mass ◽  
Hadron Production ◽  
Mass Energy ◽  
Center Of Mass Energy ◽  
Electron Positron Annihilation ◽  
Electron Positron

Hadron Production by Electron - Positron Annihilation at 5 GeV Center - of Mass Energy

1974 ◽  
Vol 32 (8) ◽  
pp. 432-435 ◽  
Author(s):  
G. Tarnopolsky ◽  
J. Eshelman ◽  
M. E. Law ◽  
J. Leong ◽  
H. Newman ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Center Of Mass ◽  
Hadron Production ◽  
Mass Energy ◽  
Center Of Mass Energy ◽  
Electron Positron Annihilation ◽  
Electron Positron

Global analysis of π± and K± fragmentation functions and their application to top quark decays considering new BABAR and Belle experimental data

2017 ◽  
Vol 95 (1) ◽  
pp. 1-8 ◽  
Author(s):  
S. Mohammad Moosavi Nejad ◽  
M. Soleymaninia ◽  
A.N. Khorramian
Keyword(s):  
Top Quark ◽  
Initial Conditions ◽  
Global Analysis ◽  
Center Of Mass ◽  
Electron Positron Annihilation ◽  
Electron Positron ◽  
Quark Decays ◽  
Fragmentation Functions ◽  
Scaled Energy ◽  
Inclusive Electron

Recently, the Belle and BABAR collaborations published the single-inclusive electron–positron annihilation data at the center of mass energies ([Formula: see text]) of 10.52 and 10.54 GeV, respectively. These new data offer one the possibility to determine the nonperturbative initial conditions of fragmentation functions (FFs) much more accurately. Here, we extract the FFs of π± and K± particles at next-to-leading order (NLO) including these new data, which are in the regions of larger scaled-energy z and lower [Formula: see text]. However, the π± and K± FFs were calculated previously, but our new analysis shows that adding these new data, for instance, changes the (u, s) → π+ FFs in the large-z region while the s → π+ FF is also changed at low z. These new data also change the u → K+ FF at low z (z < 0.2) more than at large z, but the d → K+ FF is affected at z > 0.07. The FF of g → K+ is decreased everywhere, for example, about 25% at z = 0.01. We also apply, for the first time, the extracted FFs to make our predictions for the scaled-energy distributions of π± and K± inclusively produced in top quark decays at NLO.

scholarly journals Azimuthal asymmetries from 𝜃 vacuum

2019 ◽  
Vol 34 (18) ◽  
pp. 1950095 ◽  
Author(s):  
Weihua Yang
Keyword(s):  
Quantum Chromodynamics ◽  
Azimuthal Asymmetry ◽  
Annihilation Process ◽  
Parity Symmetry ◽  
Electron Positron Annihilation ◽  
Electron Positron ◽  
Fragmentation Functions ◽  
Azimuthal Asymmetries ◽  
Inclusive Electron ◽  
Event Basis

We present the complete azimuthal asymmetries at leading twist in terms of fragmentation functions in dihadron production semi-inclusive electron–positron annihilation process. When the nontrivial [Formula: see text] vacuum is taken into consideration, the parity symmetry of quantum chromodynamics is violated. As a consequence of the [Formula: see text] [Formula: see text]-odd effects, [Formula: see text]-odd fragmentation functions would contribute to the azimuthal asymmetries. Azimuthal asymmetry coming from two interference terms with opposite signs vanishes when sum over many events. This symmetry only survives on the event-by-event basis. Azimuthal asymmetry coming from two interference terms with same signs survives and can be measured to extract the [Formula: see text]-odd fragmentation functions. We also present the hadron polarizations.

scholarly journals Double Charmonium Productions in Electron-Positron Annihilation Using Bethe-Salpeter Approach

2019 ◽  
Vol 2019 ◽  
pp. 1-6
Author(s):  
Hluf Negash ◽  
Shashank Bhatnagar
Keyword(s):  
Positron Annihilation ◽  
Cross Sections ◽  
Production Cross ◽  
Center Of Mass ◽  
Theoretical Models ◽  
Final States ◽  
Charmonium Production ◽  
Center Of Mass Energy ◽  
Electron Positron Annihilation ◽  
Electron Positron

We calculate the double charmonium production cross-section within the framework of 4×4 Bethe-Salpeter Equation in the electron-positron annihilation, at center of mass energy s=10.6GeV, that proceeds through the exchange of a single virtual photon. In this calculation, we make use of the full Dirac structure of 4D BS wave functions of these charmonia, with the incorporation of all the Dirac covariants (both leading and subleading). The calculated cross-sections for the double charmonium productions for final states, (J/Ψ,ηc), (Ψ′,ηc), (J/Ψ,ηc′), and (Ψ′,ηc′), are close to experimental data and in broad agreement with results of other theoretical models.

RADIATIVE DECAYS OF PSEUDOSCALAR (P) AND VECTOR (V) MESONS AND THE PROCESSES e+e- → ηρ(ω) AND e+e- → ϕη(η')

2009 ◽  
Vol 24 (14) ◽  
pp. 2629-2638 ◽  
Author(s):  
YU. M. BYSTRITSKIY ◽  
E. A. KURAEV ◽  
M. SEČANSKÝ ◽  
M. K. VOLKOV
Keyword(s):  
Experimental Data ◽  
Center Of Mass ◽  
Radiative Decays ◽  
Recent Experimental Data ◽  
Vector Mesons ◽  
Quark Confinement ◽  
Center Of Mass Energy ◽  
Njl Model ◽  
Electron Positron Annihilation ◽  
Electron Positron

Radiative decays of pseudoscalar and vector mesons are calculated in the frames of chiral Nambu–Jona-Lasinio (NJL) model. We use triangle quark loops of anomalous type. During the evaluation of this loop integrals we used two methods. In the first method we neglect the dependence of external momenta. In that case we reproduce the Wess–Zumino–Witten terms of effective chiral meson Lagrangian. In the second method we take into account the momenta dependence of loop integrals omitting their imaginary part. This enables us to take into account quark confinement. The application of both methods are in qualitative agreement with each other and with experimental data. The second method allows us to describe the electron–positron annihilation with production pseudoscalar and vector mesons in center-of-mass energy range from 1 to 5 GeV. Comparisons with the recent experimental data are presented.

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