Related papers: Alpha_s: from DIS to LEP
Precise measurements of the $B_s^0 - \overline{B}_s^0$ mixing parameters provide a powerful test of the Standard Model, offering potential hints to new physics. The LHCb collaboration has performed updated measurements of the $CP$-violating…
Searches for spacetime variations of fundamental constants have entered an era of unprecedented precision. New, high quality quasar spectra require increasingly refined analytic methods. In this article, a continuation in a series to…
The strong coupling constant is the least known of the coupling constants in the standard model. Nevertheless it appears in the calculations of cross sections of all the processes at the LHC. We present a review of the strong coupling…
Theoretical predictions of top-quark cross sections depend on the values of the parameters of the quantum chromodynamics Lagrangian, such as the strong coupling constant and the mass of the top quark, but also on parameters of the…
A novel method to extract the QCD coupling alpha_s from the energy evolution of the moments of the parton-to-hadron fragmentation functions at low fractional hadron momentum z, is presented. The evolution of the moments (multiplicity, peak,…
The measurement of the eta_b mass, together with a QCD result for the hyperfine splitting E_{HFS}=M_{Upsilon(1S)}-M_{eta_b}, allows us to determine the strong coupling constant alpha_s at a low energy scale. The result…
For standard model (SM) processes involving top quarks, such as top quark-antiquark pair production or single top quark production, the theoretical predictions depend on fundamental parameters of the SM like the top quark mass. Using the…
We present a measurement of the strong coupling alpha_S using data collected with the JADE detector at centre-of-mass energies between 14 and 44 GeV. The three-jet rate as a function of the transition parameter ycut is determined using the…
A high precision determination of the strong coupling constant in the MS-bar scheme at the Z-mass scale, using low energy quantities, namely pion/kaon decay constants and masses, as experimental input is presented. The computation employs…
Measurements which probe the energy dependence of $\alpha_s$, the coupling strength of the strong interaction, are reviewed. Jet counting in $e^+ e^-$ annihilation, combining results obtained in the centre of mass energy range from 22 to…
Selected topics on precision tests of the Standard Model of the Electroweak and the Strong Interaction at the LEP $e^+e^-$ collider are presented, including an update of the world summary of measurements of $\alpha_s$, representing the…
Using recently developed methods for the evaluation of five-loop amplitudes in perturbative QCD, corrections of order alpha_s^4 for the cross section of electron-positron annihilation into hadrons and for the decay rates of the Z-boson and…
The brief overview of the definite determinations of the QCD coupling constant $\alpha_s$ from the characteristics of deep-inelastic scattering processes is given.
There have been several important recent developments in precision electroweak tests. These include: the new LEP energy scan during the 1993 run; the first high-precision results on the left-right asymmetry from the SLD Collaboration at…
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…
Details are provided how GAPP evaluates the strong coupling constant from Z and tau decays and the corresponding uncertainties.
We summarize the results of recent determinations of $\alpha_s(M_Z^2)$ in NNLO QCD analyses of the deep-inelastic world data.
We test the consistency of several independent astrophysical measurements of fundamental dimensionless constants. In particular, we compare direct measurements of the fine-structure constant $\alpha$ and the proton-to-electron mass ratio…
New physics contributions to B_s-\bar{B}_s mixing can be parametrized by the size (r_s^2) and the phase (2\theta_s) of the total mixing amplitude relative to the Standard Model amplitude. The phase has so far been unconstrained. We first…
We investigate the occurrence of power terms in the running QCD coupling by analysing non-perturbative measurements of alpha_s (p) at low momenta obtained from the lattice three-gluon vertex. Our exploratory study provides some evidence for…