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Determinations of alpha_S at sqrt{s}= 14 to 44 GeV using Resummed Calculations

P. A. Movilla Fernandez

TL;DR

This work re-analyzes JADE $e^+e^-$ data from $\sqrt{s}=14$–44 GeV to determine $\alpha_s$ using $O(\alpha_S^2)$+NLLA predictions for event shapes, with hadronisation corrections from Pythia. It demonstrates that resummed QCD describes low-energy PETRA data, enabling the first $\alpha_s$ determinations at 14 and 22 GeV and confirming the QCD running of the strong coupling. The energy-dependent results are consistent with perturbative QCD expectations, and a combined $\alpha_s(M_Z)=0.1213\pm0.0006$ is obtained after including higher-order effects. Overall, the analysis extends QCD validations to lower energies and highlights the viability of resummed calculations for precision $\alpha_s$ measurements in the non-perturbative regime.

Abstract

The strong coupling constant alpha_S is determined using recently re-analysed e+e- annihilation data collected by the JADE experiment at sqrt{s}= 14 to 44 GeV. The measurements are based on O(alpha_S**2)+NLLA predictions for various event shape observables. The calculations are found to describe reliably data at the lowest energies of the e+e- continuum where non-perturbative contributions become important. The results for alpha_S are in good agreement with the QCD expectation for the running of the strong coupling constant. This is the first determination of alpha_S at sqrt{s}= 14 and 22 GeV based on resummed QCD predictions.

Determinations of alpha_S at sqrt{s}= 14 to 44 GeV using Resummed Calculations

TL;DR

This work re-analyzes JADE data from –44 GeV to determine using +NLLA predictions for event shapes, with hadronisation corrections from Pythia. It demonstrates that resummed QCD describes low-energy PETRA data, enabling the first determinations at 14 and 22 GeV and confirming the QCD running of the strong coupling. The energy-dependent results are consistent with perturbative QCD expectations, and a combined is obtained after including higher-order effects. Overall, the analysis extends QCD validations to lower energies and highlights the viability of resummed calculations for precision measurements in the non-perturbative regime.

Abstract

The strong coupling constant alpha_S is determined using recently re-analysed e+e- annihilation data collected by the JADE experiment at sqrt{s}= 14 to 44 GeV. The measurements are based on O(alpha_S**2)+NLLA predictions for various event shape observables. The calculations are found to describe reliably data at the lowest energies of the e+e- continuum where non-perturbative contributions become important. The results for alpha_S are in good agreement with the QCD expectation for the running of the strong coupling constant. This is the first determination of alpha_S at sqrt{s}= 14 and 22 GeV based on resummed QCD predictions.

Paper Structure

This paper contains 5 sections, 4 figures, 1 table.

Table of Contents

  1. Introduction
  2. Data Samples and MC Simulation
  3. Event Shapes at PETRA Energies
  4. Measurements of $\alpha_\mathrm{S}$
  5. Conclusions

Figures (4)

  • Figure 1: Hadron level distributions for $C$ at $\sqrt{s}$ = 14 to 44 GeV compared with the predictions of various QCD event generators (left). The error bars denote the total errors. Also shown are the detector correction factors $K_i$ and the normalised differences $\delta_i$ between model and data (right).
  • Figure 2: Fits of $\mathcal{O}(\alpha_\mathrm{S}^2)$+NLLA to $B_T$ at $\sqrt{s}$ = 14 to 44 GeV (left). Hadronisation corrections $K_i$ and model uncertainties are shown as well as the dependence of the results for $\alpha_\mathrm{S}$ and the $\chi^2/\mathrm{d.o.f.}$ on the variation of the fit range (right).
  • Figure 4: $\alpha_\mathrm{S}$-values derived from this analysis compared with corresponding results at higher energies. Also shown is the QCD expectation for the world average of $\alpha_\mathrm{S}$Bet00.
  • Figure :