English

Hadronic contribution to the QED running coupling $\alpha(M_{Z}^2)$

High Energy Physics - Phenomenology 2015-06-11 v4 High Energy Physics - Lattice

Abstract

We introduce a model independent method for the determination of the hadronic contribution to the QED running coupling, ΔαHAD(MZ2)\Delta\alpha_{\text{HAD}}(M_{Z}^{2}), requiring no e+ee^+e^- annihilation data as input. This is achieved by calculating the heavy-quark contributions entirely in perturbative QCD, whilst the light-quark resonance piece is determined using available lattice QCD results. Future reduction in the current uncertainties in the latter shall turn this method into a valuable alternative to the standard approach. Subsequently, we find that the precision of current determinations of ΔαHAD(MZ2)\Delta\alpha_{\text{HAD}}(M_{Z}^{2}) can be improved by some 20% by computing the heavy-quark pieces in PQCD, whilst using e+ee^+e^- data only for the low-energy light-quark sector. We obtain in this case ΔαHAD(MZ2)=275.7(0.8)×104\Delta\alpha_{\text{HAD}}(M_{Z}^{2})=275.7(0.8) \times 10^{-4}, which currently is the most precise value of ΔαHAD(MZ2)\Delta\alpha_{\text{HAD}}(M_{Z}^{2}).

Keywords

Cite

@article{arxiv.1209.4802,
  title  = {Hadronic contribution to the QED running coupling $\alpha(M_{Z}^2)$},
  author = {S. Bodenstein and C. A. Dominguez and K. Schilcher and H. Spiesberger},
  journal= {arXiv preprint arXiv:1209.4802},
  year   = {2015}
}

Comments

A misprint in Eq. (6) has been corrected

R2 v1 2026-06-21T22:09:01.225Z