Related papers: $\alpha_s$ at Zinnowitz 2004
We analyze the effect of $\pi^2$-terms in the QCD perturbative expansions for the s-channel effective coupling and observables, the effect known from the 80s. We remind that these terms can be collected into specific functions -- strong…
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…
We review the determinations of the QCD coupling $\alpha_s$ from the inclusive and exclusive modes of $\tau$-decays. The most recent $\tau$-data provide the average value $ \alpha_ s \left(M^2_\tau \right)\simeq 0.347\pm 0.030 $…
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 study the energy spectrum of bottomonium in perturbative QCD, taking alpha_s(Mz)=0.1181 +/- 0.0020 as input and fixing m_b^{MSbar}(m_b^{MSbar}) on the Upsilon(1S) mass. Contrary to wide beliefs, perturbative QCD reproduces reasonably…
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.
Being a determination at low energies, the analysis of hadronic tau decay data provides a rather precise determination of the strong coupling alpha_s after evolving the result to M_Z. At such a level of precision, even small…
If quantum chromodynamics (QCD) is renormalized by minimal subtraction (MS), at higher orders, the strong coupling constant alpha_s and the quark masses m_q exhibit discontinuities at the flavour thresholds, which are controlled by…
We show that the dependence of the total energy of the atoms on their atomic number follows a q-exponential (function proposed by C. Tsallis), for almost all elements of the periodic table. The result is qualitatively explained in terms of…
Quantum Chromodynamics predicts that the strong coupling strength $\alpha_s$ decreases with increasing energy or momentum transfer, and vanishes at asymptotically high energies. The history and the status of experimental tests of asymptotic…
This article is part of the "Review of Particle Physics" by the Particle Data Group and reviews the current status of quantum chromodynamics and the strong coupling constant $\alpha_s$. The latest updates as of August 2023 are included.
Corrections of order $\alpha_s^4$ for the axial singlet contributions for the decay rates of the $Z$-boson into hadrons are evaluated in the limit of the heavy top quark mass. Combined with recently finished ${\cal O}(\alpha_s^4)$…
The energy dependence of Tsallis statistics parameters is presented for charged pions produced at beam energies ranging between 6.3 GeV and 7 TeV. It is found that deviations from Boltzmann statistics are monotonically growing with beam…
We show that standard next-to-leading order (NLO) perturbative QCD analyses used to extract $\alpha_{s}$ from LEP data do not serve to disentangle the completely unknown renormalization scheme (RS) invariant next-NLO (NNLO) and higher-order…
We investigate the uncertainty in the value of the strong coupling $\alpha_S(M_Z^2)$ when allowing it to be a free parameter in the recent MMHT global analyses of deep-inelastic and related hard scattering data that was undertaken to…
We discuss our present knowledge of $\alpha_s$, the fundamental running coupling or effective charge of Quantum Chromodynamics (QCD). A precise understanding of the running of $\alpha_s(Q^2) $ at high momentum transfer, $Q$, is necessary…
We directly fit the experimentally measured energy dependence of the average value of 1-Thrust, <1-T>, over the e^+e^- centre-of-mass energy range Q=14 - 172 GeV to the QCD expectation obtained by integrating up the evolution equation for…
The first in m/M and fourth in Z\alpha (pure recoil) correction to a hydrogen energy level is found. This correction comprises two contributions, one coming from the atomic scale, the other from distances of the Compton wavelength order.…
We update our previous work on an analysis of the electroweak data by including new and partly preliminary data available up to the 1996 summer conferences. The new results on the Z partial decay widths into b and c hadrons now offer a…
The QCD running coupling $\alpha_s(Q^2)$ sets the strength of the interactions of quarks and gluons as a function of the momentum transfer $Q$. The $Q^2$ dependence of the coupling is required to describe hadronic interactions at both large…