Related papers: Strong Coupling Constant from the Photon Structure…
The latest experimental and theoretical developments in the high-precision determination of the strong coupling $\alpha_s$ are briefly reviewed. Six groups of observables: (i) lattice QCD data, (ii) hadronic $\tau$ decays, (iii)…
We present in analytic form the matching conditions for the strong coupling constant alpha_s^(n_f)(mu) at the flavour thresholds to three loops in the modified minimal-subtraction scheme. Taking into account the recently calculated…
We present an up-to-date analysis for a precise determination of the effective fine structure constant and discuss the prospects for future improvements. We advocate to use a determination monitored by the Adler function which allows us to…
Hadronic event shape distributions are determined from data in e+e- collisions between 183 and 207 GeV. From these the strong coupling alpha_s is extracted in O(alpha_s^2), NLLA and matched O(alpha_s^2)+NLLA theory. Hadronisation…
We determine the strong coupling constant $\alpha_s(M_Z)$ from the static QCD potential by matching a lattice result and a theoretical calculation. We use a new theoretical framework based on operator product expansion (OPE), where…
Determinations of the strong coupling strength, $\alpha_s$, are summarised and a new world average value of $\alpha_s (M_Z)$ is determined, using a new method of pre-averaging results within classes of measurements like hadronic $\tau$…
Motivated by recent preliminary results from the SLD Collaboration on the measurement of angle-dependent B-Bbar energy correlations in Z^0 -> b bbar events, we propose a class of observables that can be computed as a power expansion in the…
The prospects for the measurement of the strong coupling constant alpha_msbar(M_Z) to a relative uncertainty of 1% are discussed. Particular emphasis is placed on the implications relating to future High Energy Physics facilities.
Hadronic final states with a hard isolated photon are studied using data taken at centre-of-mass energies around the mass of the Z0 boson with the OPAL detector at LEP. The strong coupling alpha S is extracted by comparing data and QCD…
The current status of measurements of the strong coupling constant from different reactions is reviewed. Including new results presented at the 1996 ICHEP conference, a global average alpha_s(Mz) = 0.118 +- 0.003 is obtained.
The prediction of the strong coupling constant in grand unified theories is reviewed, first in the standard model, then in the supersymmetric version. Various corrections are considered. The predictions in both supergravity-induced and…
Results are presented from a study of the structure of high energy hadronic events recorded by the L3 detector at sqrt(s)>192 GeV. The distributions of several event shape variables are compared to resummed O(alphaS^2) QCD calculations. We…
We present results by the ALPHA collaboration for the $\Lambda$-parameter in 3-flavour QCD and the strong coupling constant at the electroweak scale, $\alpha_s(m_Z)$, in terms of hadronic quantities computed on the CLS gauge configurations.…
The strong coupling constant alpha_S is determined using recently re-analysed e+e- annihilation data collected by the JADE experiment at sqrt{s}= 14 to 44 GeV. The measurements are based on O(alpha_S**2)+NLLA predictions for various event…
We present a first attempt to experimentally extract an effective strong coupling constant that we define to be a low Q2 extension of a previous definition by S. Brodsky et al. following an initial work of G. Grunberg. Using Jefferson Lab…
In this work we present lattice calculations of the masses of P-wave mesons using Monte Carlo simulations. Our valence fermions are defined by the Wilson action. Our gauge fields are generated with both dynamical staggered fermions at a…
The precision measurements of the strong coupling constant, alphas, and its energy-scale dependence carried out at HERA by the H1 and ZEUS Collaborations are reviewed. An average value of alphas(Mz) = 0.1186 +- 0.0011 (exp.) +- 0.0050 (th.)…
Hadronic final states with a hard isolated photon are studied using data taken at centre-of-mass energies around $\Mz$ with the OPAL detector at LEP. The strong coupling $\as$ is extracted by fitting event shape variables for the reduced…
The spectral functions of the vector current and the axial-vector current have been measured in hadronic tau decays using the OPAL detector at LEP. Within the framework of the Operator Product Expansion a simultaneous determination of the…
A summary is given of the current status of measurements of the strong coupling constant $\alpha_s$ performed at LEP. These include measurements from inclusive observables as well as from event shape variables. Recent results based on power…