Related papers: QCD at LEP
In this Report, QCD results obtained from a study of hadronic event structure in high energy e^+e^- interactions with the L3 detector are presented. The operation of the LEP collider at many different collision energies from 91 GeV to 209…
New results from measurements of the strong coupling constant $\alpha_s(M_Z)$ at LEP are presented. In particular, a new LEP combination of results based on event-shape variables has become available, where a new method for the estimation…
Studies of hadronic final states of $e^+e^-$ annihilations, observed at the Large Electron Positron Collider LEP at CERN, are reviewed. The topics included cover measurements of $\alpha_s$, hadronic event shapes and hadronisation studies,…
In the events of the type $e^+e^- \rightarrow W^+W^- \rightarrow$ 4 jets, $e^+e^- \rightarrow t\bar{t} \rightarrow bW^+\bar{b}W^-$, particle production could depend in a non-trivial way on the kinematics of the process. It is shown that QCD…
We review the current status of analyses of multijet final states in e+e- annihilation. Results for jet observables from LEP 1, LEP 2 and from the reanalysis of the PETRA experiment JADE will be presented. A determination of the b-quark…
A remarkable number of studies have been performed at LEP in the field of two-photon physics in the last four years. These results represent a very important contribution to the understanding of strong interactions at low energies. In…
Data from electron positron annihilations at different center of mass energies are collected by the four LEP experiments. Direct tests of hard QCD are performed by measuring and analysing event shape observables.
In quark-antiquark pair production at LEP, many features of the hadronic final state can be predicted by QCD. Using data collected by the OPAL experiment, we present the statistical distributions of fourteen "event shape observables," which…
I review few recent QCD results in $e^+e^-$, $ep$ and $p\bar{p}$ collisions. Furthermore, I discuss recent studies in power suppressed effects, ongoing progress in next-to-next-to-leading QCD calculations, and some recent puzzling results…
Studies of event shape observables at PETRA and LEP energies are presented. Previously published determinations of the strong coupling constant \alpha_s at \sqrt{s} = 35 and 44 GeV are complemented using new resummed QCD calculations for…
A combination of measurements of alpha_s in e+e- annihilation at LEP is presented. Distributions of various event-shape variables measured by ALEPH, DELPHI, L3 and OPAL at centre-of-mass energies from 41 GeV to 206 GeV are analysed in a…
We have investigated some observable consequences of colour reconnection in the reaction e+e- -> W+ W- -> q_1 qbar_2 q_3 qbar_4. We use a measure based on the momentum structure of the event, comparing reconnected events with `standard'…
I will attempt to survey some selected physics issues on QCD interconnection phenomena in the processes $e^+e^-\to W^+W^-\to$ 4 jets and $e^+e^-\to t\bar t \to b W^+\bar b W^-$. Possible consequences for LEP2 and future linear $e^+e^-$…
Recent experimental results on color coherence phenomena from e+e-, ep, and ppbar collisions are presented. The data are compared to analytic perturbative QCD calculations based on the modified leading logarithm approximation and the local…
This talk contains a subjective selection of interesting results on Z$^0$ decays, presented by the LEP and SLC groups. The emphasis is on soft and semihard QCD physics. Results are put in a theoretical context, and the limits of our current…
The size of non-perturbative corrections to event shape observables is predicted to fall like powers of the inverse centre of mass energy. These power corrections are investigated for different observables from $e^+e^-$-annihilation…
The analyses of recent LEP data provide us with a rich ground for pQCD and LPHD tests. A number of non-trivial effects predicted in the framework of MLLA are experimentally verified. Recent measurements also enrich our knowledge about the…
We summarise the latest experimental QCD studies based on data from LEP. Measurements of the quark and gluon jet fragmentation functions are discussed, including a new algorithm to infer the properties of unbiased gluon jets. We describe a…
In the reaction e+e- -> WW -> (q_1 qbar_2)(q_3 qbar_4) the usual hadronization models treat the colour singlets q_1 qbar_2 and q_3 qbar_4 coming from two W bosons independently. However, since the final state partons may coexist in space…
The effects of the final state interaction phenomenon known as colour reconnection are investigated at centre-of-mass energies in the range sqrt(s) ~ 189-209 GeV using the OPAL detector at LEP. Colour reconnection is expected to affect…