Determination of the strong coupling αS from hadronic event shapes with $\mathcal{O}(\ensuremath {\alpha _{\mathrm {S}}}^{3})$ and resummed QCD predictions using JADE data

Abstract

Event Shape Data from e + e − annihilation into hadrons collected by the JADE experiment at centre-of-mass energies between 14 GeV and 44 GeV are used to determine the strong coupling α S . QCD predictions complete to next-to-next-to-leading order (NNLO), alternatively combined with resummed next-to-leading-log-approximation (NNLO + NLLA) calculations, are used. The combined value from six different event shape observables at the six JADE centre-of-mass energies using the NNLO calculations is The stability of the NNLO and NNLO + NLLA results with respect to missing higher order contributions, studied by variations of the renormalisation scale, is improved compared to previous results obtained with NLO + NLLA or with NLO predictions only. The observed energy dependence of α S agrees with the QCD prediction of asymptotic freedom and excludes absence of running with 99% confidence level.

Determination of α S using OPAL hadronic event shapes at $\sqrt{s} = 91\mbox{--}209~\mathrm{GeV}$ and resummed NNLO calculations

“…energies between √ s = 91 GeV and 206 GeV, using NNLO predictions and ALEPH data, were presented in [11]. This was followed by measurements between √ s = 14 GeV and √ s = 44 GeV [12] and between √ s = 91 GeV and √ s = 206 GeV [13] based on comparing JADE or ALEPH data with NNLO plus matched NLLA calculations. The strong coupling has also been determined at NNLO from the threejet rate at LEP [14].…”

“…The data sample is that of the OPAL Collaboration at LEP. Hadronization corrections are treated in the manner described in [2,11,12,15]. The study is based on the same measurements of event shape variables, the same fit ranges (except for y D 23 as discussed below), and the same Monte Carlo models for detector and hadronization corrections as those in [15].…”

Implications of an R-Scan for Charm Physics

“…The choice of the strong coupling constant α s , its central value as well as its error, is a matter of dispute. 16 In our analysis α s (M Z ) = 0.1189 ± 0.0020 has been adopted. The dependence of our result on α s can be directly deduced from the final result where the parametric α s -dependence affecting both the evaluation of m c (3 GeV) and its evolution from µ = 3 GeV to 126 GeV are combined.…”

Antenna subtraction at NNLO with hadronic initial states: double real initial-initial configurations

“…The antenna functions are derived systematically from physical matrix elements [47][48][49]. This formalism has been applied in the derivation of NNLO corrections to three-jet production in electron-positron annihilation [50][51][52][53][54] and related event shapes [55][56][57][58][59], which were used subsequently in precision determinations of the strong coupling constant [60][61][62][63][64][65][66][67][68][69][70]. The formalism can be extended to include massive fermions [71][72][73][74].…”