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We present a determination of the strong coupling constant $\alpha_s(m_Z)$ based on the NNPDF3.1 determination of parton distributions, which for the first time includes constraints from jet production, top-quark pair differential…

High Energy Physics - Phenomenology · Physics 2018-07-10 Richard D. Ball , Stefano Carrazza , Luigi Del Debbio , Stefano Forte , Zahari Kassabov , Juan Rojo , Emma Slade , Maria Ubiali

The problem of determination of $\alpha_{s}$ and the condensates from the moments of invariant mass distribution in the semileptonic tau decays is considered. It is investigated how the extracted values of alpha_s(m^{2}_{tau}) and the…

High Energy Physics - Phenomenology · Physics 2009-10-30 P. A. Raczka

The measurement of the trilinear couplings A in the part of the Lagrangian which breaks supersymmetry softly will be a difficult experimental task. In this report the heavy Higgs decays H,A -> stau_1 stau_2 to stau pairs are investigated…

High Energy Physics - Phenomenology · Physics 2009-01-07 S. Y. Choi , H. -U. Martyn , P. M. Zerwas

We have applied so-called `optimised' perturbation theory to resolve the renormalisation-scale (mu) ambiguity of exact O(alpha_s^2) QCD calculations of event shape observables in e+e- --> hadrons. We fitted the optimised predictions for 15…

High Energy Physics - Phenomenology · Physics 2009-10-28 P. N. Burrows , H. Masuda , D. Muller , Y. Ohnishi

We review recent work to determine the strange quark mass m_s as well as the proposal to determine |V_{us}| using hadronic tau decay data. The recent update of the strange spectral function by OPAL and their moments of the invariant mass…

High Energy Physics - Phenomenology · Physics 2016-09-06 Elvira Gamiz , Matthias Jamin , Antonio Pich , Joaquim Prades , Felix Schwab

An update of measurements of the strong coupling constant $\alpha_s$ is given, representing the status of September 2002. The results convincingly prove the energy dependence of $\alpha_s$ and are in excellent agreement with the…

High Energy Physics - Experiment · Physics 2011-03-23 Siegfried Bethke

In this paper we fix our attention, on hadron structure, and show that also the strong interaction strength alpha_S, ordinarily called the "(perturbative) coupling--constant square}", can be evaluated within our theory, and found to…

General Physics · Physics 2011-04-15 Erasmo Recami , Tonin-Zanchin , Antonino Del Popolo , Mario Gambera

We describe the determination of the strong coupling constant $\alpha_s(M_Z^2)$ and of the charm-quark mass $m_c(m_c)$ in the $\bar{\rm MS}$-scheme, based on the QCD analysis of the unpolarized World deep-inelastic scattering data. At NNLO…

High Energy Physics - Phenomenology · Physics 2015-06-16 S. Alekhin , J. Blümlein , S. Moch

This paper describes a measurement of the Michel parameters, \eta, \rho, \xi, \xi\delta, and the average \nu_{\tau} helicity, h_{\nu_{\tau}}, in tau lepton decays together with the first measurement of the tensor coupling in the weak…

High Energy Physics - Experiment · Physics 2010-05-28 The DELPHI Collaboration , P. Abreu

Sufficiently inclusive observables in the decay of the tau lepton can be calculated using the methods of perturbative QCD. These include the asymmetry parameter $A_\tau$ that determines that angular distribution of the total hadron momentum…

High Energy Physics - Phenomenology · Physics 2009-10-30 Eric Braaten

We present the first determination of the strong coupling constant from a fit of next-to-next-to-leading order QCD predictions to event-shape variables, measured in $e^+e^-$ annihilations at LEP. The data have been collected by the ALEPH…

High Energy Physics - Phenomenology · Physics 2008-12-30 G. Dissertori , A. Gehrmann-De Ridder , T. Gehrmann , E. W. N. Glover , G. Heinrich , H. Stenzel

We extend our recent analytic study of the strong coupling $\alpha_{\rm eff}$ in the nonperturbative and near-perturbative regimes~\cite{deTeramond:2024ikl} by imposing rigorous renormalization-group results from asymptotically free gauge…

High Energy Physics - Phenomenology · Physics 2025-05-27 Guy F. de Teramond , Arpon Paul , Hans Gunter Dosch , Stanley J. Brodsky , Alexandre Deur , Tianbo Liu , Raza Sabbir Sufian

Precise measurements of the lepton properties provide stringent tests of the Standard Model and accurate determinations of its parameters. We overview the present status of tau physics, highlighting the most recent developments, and discuss…

High Energy Physics - Phenomenology · Physics 2014-03-05 Antonio Pich

A critical review of hadronic tau decay data based determinations of |V_{us}| is given, focussing on the impact of the slow convergence of the integrated D=2 OPE series for the conventional flavor-breaking sum rule determination and the…

High Energy Physics - Phenomenology · Physics 2011-09-20 Kim Maltman

The pure leptonic or semileptonic character of tau decays makes them a good laboratory to test the structure of the weak currents and the universality of their couplings to the gauge bosons. The hadronic $\tau$ decay modes constitute an…

High Energy Physics - Phenomenology · Physics 2011-04-15 A. Pich

The strong coupling alpha_s is a fundamental parameter of the Standard Model. In comparison to parameters like alpha_em and M_Z it is relatively poorly known. However the precision of alpha_s measurements has improved dramatically in recent…

High Energy Physics - Phenomenology · Physics 2007-05-23 W. J. Stirling

We present a strong coupling constant extraction at Next-to-Leading Order QCD accuracy using ATLAS Z+2,3,4 jets data. This is the first extraction using processes with a dependency to high powers of the coupling constant. We obtain values…

High Energy Physics - Phenomenology · Physics 2018-03-21 Mark Johnson , Daniel Maître

We discuss the ratio of hadronic to leptonic tau-decays, that can be expanded in an operator product expansion. The sensitivity to the strange mass is increased, if only the flavor-breaking difference of strange to non-strange currents is…

High Energy Physics - Phenomenology · Physics 2007-05-23 Felix Schwab

We present a new QCD sum rule with high sensitivity to the continuum regions of charm and bottom quark pair production. Combining this sum rule with existing ones yields very stable results for the MS-bar quark masses, m_c(m_c) and…

High Energy Physics - Phenomenology · Physics 2008-11-26 Jens Erler , Mingxing Luo

The determination of alpha_s from hadronic tau decays is impeded by the fact that two choices for the renormalisation group resummation, namely fixed-order (FOPT) and contour-improved perturbation theory (CIPT), yield systematically…

High Energy Physics - Phenomenology · Physics 2015-05-20 Matthias Jamin