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The LEP experiments have measured event shapes using data taken at e+e- center-of-mass energies ranging from 91 GeV to 209 GeV. Using the final LEP event shape measurements, a combined value of the strong coupling constant alpha_s(M_Z) has…

High Energy Physics - Experiment · Physics 2017-08-23 Stefan Soldner-Rembold

We present a new determination of the strong coupling constant $\alpha_s$ from a global QCD analysis CT25 of parton distribution functions (PDFs) that incorporates high-precision experimental measurements from the Run-2 of the Large Hadron…

High Energy Physics - Phenomenology · Physics 2026-03-18 Alim Ablat , Sayipjamal Dulat , Marco Guzzi , Joey Huston , Kirtimaan Mohan , Pavel Nadolsky , Dan Stump , C. -P. Yuan

We present a new determination of the strong coupling constant alpha_s through the scaling violations in the fragmentation functions for charged pions, charged kaons, and protons. In our fit we include the latest e+e- annihilation data from…

High Energy Physics - Phenomenology · Physics 2009-10-31 B. A. Kniehl , G. Kramer , B. Pötter

The QCD coupling alpha_s is determined from a combined analysis of experimental e+e- and e-p jet data confronted to theoretical predictions of the energy evolution of the parton-to-hadron fragmentation functions (FFs) moments…

High Energy Physics - Phenomenology · Physics 2015-06-23 Redamy Pérez-Ramos , David d'Enterria

Measurements of transverse energy$-$energy correlations and their associated azimuthal asymmetries in multijet events are presented. The analysis is performed using a data sample corresponding to 139 $\mbox{fb\(^{-1}\)}$ of proton$-$proton…

High Energy Physics - Experiment · Physics 2023-08-15 ATLAS Collaboration

Event shape distributions in $e^+e^-$ annihilation are determined from the DELPHI data taken between 183 and 207\gev. From these the strong coupling $\alpha_s$ is extracted with several techniques. Together with the results from other LEP2…

High Energy Physics - Phenomenology · Physics 2008-11-26 Oliver Passon

We extract the value of the strong coupling constant alpha_s from a single-parameter pointlike fit to the photon structure function F_2^gamma at large x and Q^2 and from a first five-parameter full (pointlike and hadronic) fit to the…

High Energy Physics - Phenomenology · Physics 2009-11-07 S. Albino , M. Klasen , S. Soldner-Rembold

Since 1995, LEP has steadily increased the center of mass energy of the colliding beams, from the M_Z resonance to 133, 161 and 172 GeV. New measurements of the strong coupling constant, alpha_s, at these energies have been performed by the…

High Energy Physics - Experiment · Physics 2008-02-03 S. Marti i Garcia

New results from measurements of the strong coupling constant $\alpha_s(M_Z)$ at LEP are presented. In particular, a new LEP combination of results based on event-shape variables has become available, where a new method for the estimation…

High Energy Physics - Experiment · Physics 2009-11-07 G. Dissertori

We present the first fully analytic calculation of the Quantum Chromodynamics (QCD) event shape observable Energy-Energy Correlation in electron-positron annihilation at Next-To-Leading Order (NLO). This result sheds light on the analytic…

High Energy Physics - Phenomenology · Physics 2018-07-20 Lance J. Dixon , Ming-xing Luo , Vladyslav Shtabovenko , Tong-Zhi Yang , Hua Xing Zhu

We study the matching of the next-to-leading logarithmic approximation (NLLA) onto the fixed next-to-next-to-leading order (NNLO) calculation for event shape distributions in electron-positron annihilation. The resulting theoretical…

High Energy Physics - Phenomenology · Physics 2008-11-26 T. Gehrmann , G. Luisoni , H. Stenzel

We have conducted the first simultaneous global fit of the strong coupling constant $\alpha_s$ and the Collins-Soper (CS) kernel using the energy-energy correlators (EEC) of $e^{+} e^{-}$ collisions in the back-to-back limit. This analysis,…

High Energy Physics - Phenomenology · Physics 2024-11-27 Zhong-Bo Kang , Jani Penttala , Congyue Zhang

We present a comprehensive study of the determination of the strong coupling from $\tau$ decay, using the most recent release of the experimental ALEPH data. We critically review all theoretical strategies used in previous works and put…

High Energy Physics - Phenomenology · Physics 2016-09-08 Antonio Pich , Antonio Rodríguez-Sánchez

We present a novel method for precisely determining the running QCD coupling constant $\alpha_s(Q^2)$ over a wide range of $Q^2$ from event shapes for electron-positron annihilation measured at a single annihilation energy $\sqrt{s}$. The…

High Energy Physics - Phenomenology · Physics 2019-11-20 Sheng-Quan Wang , Stanley J. Brodsky , Xing-Gang Wu , Jian-Ming Shen , Leonardo Di Giustino

We report on a complete calculation of electroweak production of top quark pairs in $e^+e^-$ annihilation at next-to-next-to-leading order in Quantum Chromodynamics. Our setup is fully differential and can be used to calculate any…

High Energy Physics - Phenomenology · Physics 2015-01-07 Jun Gao , Hua Xing Zhu

The QCD coupling alpha_s is determined at NLO*+NMLLA accuracy from the comparison of experimental jet data to theoretical predictions of the energy-evolution of the parton-to-hadron fragmentation function moments (multiplicity, peak, width,…

High Energy Physics - Phenomenology · Physics 2014-10-20 David d'Enterria , Redamy Pérez-Ramos

We use a recently proposed non-perturbative model, based on an effective strong coupling constant and free from tunable parameters, to study c-flavoured hadron production in e+e- annihilation. Charm-quark production is described in the…

High Energy Physics - Phenomenology · Physics 2010-03-25 Gennaro Corcella , Giancarlo Ferrera

We present a measurement of the strong coupling alpha_S using the three-jet rate measured with the Durham algorithm in e+e- -annihilation using data of the JADE experiment at centre-of-mass energies between 14 and 44 GeV. Recent theoretical…

High Energy Physics - Experiment · Physics 2015-06-05 Jochen Schieck , Siegfried Bethke , Stefan Kluth , Christoph Pahl , Zoltan Trocsanyi , the JADE Collaboration

The first measurement of two-particle angular correlations for charged particles produced in $e^+e^-$ annihilation up to $\sqrt{s}$ = 209 GeV is presented. Hadronic $e^+e^-$ data, archived at center-of-mass energies ranging from 91 to 209…

High Energy Physics - Experiment · Physics 2024-01-30 Yu-Chen Chen , Yen-Jie Lee , Yi Chen , Paoti Chang , Chris McGinn , Tzu-An Sheng , Gian Michele Innocenti , Marcello Maggi

The strong coupling constant is one of the fundamental parameters of the standard model of particle physics. In this review I will briefly summarise the theoretical framework, within which the strong coupling constant is defined and how it…

High Energy Physics - Experiment · Physics 2016-10-12 G. Dissertori