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    • Keywords


      Transverse momenta; three-jet rate; event shapes.

    • Abstract


      The hadronic events from the $e^+ e^−$ annihilation data at the centre-of-mass energies ranging from 60 to 197 GeV were studied. The AMY and OPAL Collaborations offered a unique opportunity to test QCD by measuring the energy dependence of different observables. The coupling constant, $\alpha_s$, was measured by two different methods: first by employing the three-jet observables. Combining all the data, the value of as at next-to-next leading order (NNLO) was determined to be $0.117 \pm 0.004$(hard) ± 0.006(theo). Secondly, from the event-shape distributions, the strong coupling constant, $\alpha_s$, was extracted at NNLO and it’s evaluation was tested with the energy scale. The results were consistent with the running of $\alpha_s$, expected from QCD predictions. Averaging over different observables, $\alpha_s$ was determined to be $0.115 \pm 0.007$(hard) $\pm 0.003$(theo).

    • Author Affiliations


      Mohammad Ebrahim Zomorrodian1 Alireza Sepehri1 Tooraj Ghaffary1 Parvin Eslami1

      1. Department of Physics, Ferdowsi University of Mashhad, Mashhad 91775-1436, Khorasane, Razavi, Iran
    • Dates

  • Pramana – Journal of Physics | News

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      Posted on July 25, 2019

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