Related papers: $R_{e^+ e^-}$ and an effective QCD charge
I survey a number of interesting tests of quantum chromodynamics at the amplitude level which can be carried out in electron-positron annihilation and in photon-photon collisions at low energy, including measurements of fundamental…
A pedagogical review is given of precise tests of QCD in electron-positron annihilation. Emphasis is placed on measurements that have served to establish QCD as the correct theory of strong interactions, as well as measurements of the…
The Modified Leading Log Approximation of QCD and the local parton hadron duality picture are shown to give a fully satisfactory description of data on charged particle energy spectra in $e^+e^-$ annihilation. The analysis of data in terms…
We begin with short review of the analytic approach (AA) to QCD recently developed and applied to the process of $e^+e^-$ annihilation into hadrons at low energies. Besides summary of the theoretical description of smeared experimental data…
An evaluation of the effective QED coupling at the scale M_Z is presented. It employs the predictions of perturbative QCD for the cross section of electron positron annihilation into hadrons up to order \alpha_s^2, including the full quark…
Electron-positron annihilation into hadrons plus an energetic photon from initial state radiation allows the hadronic cross-section to be measured over a wide range of energies. The full next-to-leading order QED corrections for the…
The string+${}^3P_0$ model of spin-dependent hadronization is applied to the fragmentation of a string stretched between a quark and an antiquark with entangled spin states, assumed to be produced in the $e^+e^-$ annihilation process. The…
We discuss the use of the optimization procedure based on the Principle of Minimal Sensitivity to the third-order calculation of {\mbox{${R_{e^+e^-}}$}}. The effective coupling constant remains finite allowing us to apply the…
The new result for the third-order QCD corrections to R_{e^+e^-}, unlike the old, incorrect result, is nicely compatible with the principle-of-minimal-sensitivity optimization method. Moreover, it leads to infrared fixed-point behaviour:…
Theory results on precision measurements in electron-positron annihilation at low and high energies are collected. These cover pure QCD calculations as well as mixed electroweak and QCD results, involving light and heavy quarks. The impact…
We re-evaluate the non-perturbative contribution to the thrust distribution in $e^+e^-\to$ hadrons, in the light of the latest experimental data and the recent NNLO perturbative calculation of this quantity. By extending the calculation to…
In this paper, we employ chiral effective field theory to study the process of electron-positron annihilation into four pions in the low energy region within $E_{c.m.}\leq 0.6$ GeV. The prediction of the cross section is obtained through…
We present a novel method for precisely determining the QCD running coupling from $R_{\rm uds}$ measurements in electron-positron annihilation. When calculating the fixed-order perturbative QCD (pQCD) approximant of $R_{\rm uds}$, its…
A detailed investigation of the theoretical ambiguities present in the QCD description of photon production in $e^+e^-$ annihilation is given. It is pointed out that in a well-defined perturbative analysis it is necessary to subtract the…
The explicit expression for the R-ratio of electron-positron annihilation into hadrons, which properly accounts for all the effects due to continuation of the spacelike perturbative results into the timelike domain, is obtained at an…
We have studied hadronic events from e+e- annihilation data at centre-of-mass energies of sqrt{s}=172, 183 and 189 GeV. The total integrated luminosity of the three samples, measured with the OPAL detector, corresponds to 250 pb^-1. We…
The excitation curve of e+e- annihilation into four charged pions in the rho(770) region is calculated using three existing models with rho mesons and pions in intermediate states supplemented by Feynman diagrams with the a_1(1260)pi…
Multiparticle production in hadron and lepton interactions still attracts our attention. Simulation by using Monte Carlo event generators is performed before planning any experiment. But it often overestimates (or underestimates)…
We present a comprehensive global analysis of Energy-Energy Correlation (EEC) data in electron-positron annihilation into hadrons, spanning a wide range of center-of-mass energies ($7.7\,\,\text{GeV}\!\leq\!\sqrt{s}\!\leq\!…
Experimental data on the total cross section of $e^+ e^-$ annihilation into hadrons are confronted with QCD and the operator product expansion using finite energy sum rules. Specifically, the power corrections in the operator product…