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Event shape; quantum chromodynamics; next-to-next-to-leading order correction.

The next-to-next-to-leading order (NNLO) quantum chromodynamics (QCD) correction to the first three moments of the four event-shape variables in electron–positron annihilation, the thrust, heavy jet mass, wide, and total jet broadening, is computed. It is observed that the NNLO correction gives a better agreement between the theory and the experimental data. Also, by using the above observables, the strong coupling constant ($\alpha_{s}$) is determined and how much its value is affected by the NNLO correction is demonstrated. By combining the results for all variables at different centre-of-mass energies $\alpha_{s} (M_{Z^{\circ}}) = 0.1248 \pm 0.0009 ({\text{exp.}})_{-0.0144}^{+0.0283} ({\text{theo.}})$ is obtained.

Samira Shoeibi Mohsenabadi¹ Mohammad Ebrahim Zomorrodian¹

1. Department of Physics, Ferdowsi University of Mashhad, Mashhad 91775-1436, Iran

Published

November 2013

Manuscript received

22 April 2013

Manuscript revised

4 August 2013

Accepted

13 August 2013

Early published

18 October 2013