Order alpha**4(s) QCD Corrections to Z and tau Decays

Jan, 2008
5 pages
Published in:
  • Phys.Rev.Lett. 101 (2008) 012002
e-Print:
Report number:
  • SFB-CPP-08-04,
  • TTP08-01

Citations per year

2004200920142019202401020304050
Abstract: (arXiv)
Using recently developed methods for the evaluation of five-loop amplitudes in perturbative QCD, corrections of order alpha_s^4 for the cross section of electron-positron annihilation into hadrons and for the decay rates of the Z-boson and the tau-lepton into hadrons are evaluated. The new terms lead to a significant stabilization of the perturbative series, to a reduction of the theory uncertainly in the strong coupling constant alpha_s, as extracted from these measurements, and to a small shift of the central value, moving two central values closer together. The agreement between two values of alpha_s measured at vastly different energies constitutes a striking test of asymptotic freedom. Combining the results from Z and tau decays we find alpha_s(M_Z)=0.1198 \pm 0.0015 as one of the most precise and presently only NNNLO result for the strong coupling constant.
  • 13.35.Dx
  • 13.85.Lg
  • 12.38.Bx
  • electron positron: annihilation
  • hadron: electroproduction
  • Z0: hadronic decay
  • Z0: width
  • tau: hadronic decay
  • tau: width
  • cross section
Loading ...