Next-to-next-to-leading order calculation of the strong coupling constant e???e?‘? by using moments of event-shape variables

摘要

The next-to-next-to-leading order (NNLO) quantum chromodynamics (QCD) correction to the first three moments of the four event-shape variables in electrona€“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 (e???e?‘?) 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 e???e?‘? $(M_{Z^{?°}})$ = 0.1248 ?± 0.0009 $({ ext{exp.}})_{-0.0144}^{+0.0283} ({ ext{theo.}})$ is obtained.