Related papers: QCD at LEP
Experimental tests of QCD predictions for event shape distributions combining contributions from hard and soft processes are discussed. The hard processes are predicted by perturbative QCD calculations. The soft processes cannot be…
A complete numerical solution of the evolution equation for parton multiplicities in quark and gluon jets with initial conditions at threshold is presented. Data on both hadron and jet multiplicities in e+e- annihilation are well described…
Deep inelastic e^+ scattering data, taken with the H1 detector at HERA, are used to study the event shape variables thrust, jet broadening and jet mass in the current hemisphere of the Breit frame over a large range of momentum transfers Q…
The implementation of QED initial-state radiative corrections in the process of four-fermion production at LEP200 and higher-energy e+e- colliders is discussed. Because of the presence of charged-current processes, this is a nontrivial…
The results of evaluation of mixed QED X QCD corrections to R(s) in e^+e^- annihilation and R_{\tau} in hadronic decay of the \tau lepton to O(\alpha^n\alpha_s^m), m+n \leq 3, are presented. The net effect on \alpha_s(M_Z) from the Z decay…
Precision studies of QCD at electron-positron colliders are based on measurements of event shapes and jet rates. To match the high experimental accuracy, theoretical predictions to next-to-next-to-leading order (NNLO) in QCD are needed for…
We present results obtained from a study of the structure of hadronic events recorded by the L3 detector at various centre-of-mass energies. The distributions of event shape variables and the energy dependence of their mean values are…
We present next-to-leading order QCD predictions for single-inclusive and di-jet observables, relevant to the collisions of two on-shell photons, obtained with a recently completed computation based upon the subtraction method. We compare…
The astounding Physics results obtained with high-energy colliders in the last two decades owe much to an impressive progress in the understanding of the dynamics of strong interactions. I give here a personal overview of how the advance in…
Interactions between the products of the hadronic decays of different Ws in WW pair events can occur at several stages: from the colour rearrangement between the quarks coming from the primary branching, to the gluon exchange during the…
A summary of results obtained from e^+e^- annihilations at LEP is given. The precision measurements around the Z resonance, the results from charged gauge boson production and searches for new particles are reviewed. Particular emphasis is…
Jet and di-jet production are studied in collisions of quasi-real photons collected during the LEP2 program at e+e- center-of-mass energies from 189 to 209 GeV. OPAL reports good agreement of NLO perturbative QCD with the measured…
Final-state interactions and interference phenomena that could affect the value of the W mass reconstructed from hadronic WW decays at LEP2 are reviewed, and possible areas for future investigation are identified.
Radiative returns to the Z resonance (Zgamma events) provide a method to determine the centre-of-mass energy of the high energy e+e- colliders and already at LEP2. The method is applied for the data collected with the ALEPH detector in 1997…
The process e+e- to nu barnu + gamma with a distinctive ``photon-plus-missing-energy'' signal can serve as an important tool to search for new physics at LEP2. It can be exploited to measure the WW gamma coupling, or to search for weakly…
A short review of the history and a 'slide-show' of QCD tests in $e^+e^-$ annihilation is given. The world summary of measurements of $\alpha_s$ is updated.
An overview of the latest results of the LEP collaborations on QCD measurements in photon-photon collisions is presented, including measurements of the total hadronic cross-section, the production of heavy quarks and dijets and the…
The process e+ e- -> n gamma with n>=2 is studied at centre-of-mass energies ranging from \root(s)=192 to 208 GeV. The data sample corresponds to a total integrated luminosity of 427 1/pb. The total and differential cross sections are found…
We discuss non-perturbative QCD contributions to jet observables, computing their dependence on the jet radius R, and on the colour and transverse momentum of the parton initiating the jet. We show, using analytic QCD models of power…
We introduce and motivate the method of effective chsrges, and consider how to implement an all-orders resummation of large kinematical logarithms in this formalism. Fits for QCD \Lambda and power corrections are performed for the e+e-…