Improving alpha_QED(M_Z^2) and the charm mass by analytic continuation

Abstract

The standard determination of the QED coupling on the Z pole is performed using the latest available data for R. The direct application of analytic continuation techniques is found not to improve the accuracy of the value of α(M_Z^2). However they help to resolve an ambiguity in the values of R in the energy region \sqrt{s} < 2 GeV, which, in turn, reduces the uncertainty in α(M_Z^2). Moreover, they provide a sensitive determination of the mass of the charm quark. The favoured solution, which uses the inclusive data for R for \sqrt{s} < 2 GeV, has a pole mass m_c = 1.33-1.40 GeV and α^{-1}(M_Z^2) = 128.972 +/- 0.026; whereas if the sum of the exclusive channels is used to determine R in this region, we find α^{-1}(M_Z^2) = 128.941 +/- 0.029.

LaTeX, 23 pages, 7 eps figures, typos removed, accepted by Eur. Phys. J. C

Cited by in corpus (11)

• Predictions for g-2 of the muon and alpha_QED(M_Z^2)
• Present Status of Inclusive Rare B Decays
• Determination of ${\alpha }_s$ and heavy quark masses from recent measurements of $R(s)$
• The SM prediction of g-2 of the muon
• Results and Techniques of Multi-Loop Calculations
• A precise determination of the charm quark's mass in quenched QCD
• All-orders infrared freezing of observables in perturbative QCD
• Simple Formulae for Sin^2 theta_eff^lept, M_W, Gamma_l, and their Physical Applications
• Calculation of ${\bar{\alpha }}_{Q.E.D.}$ on the Z
• The Higgs puzzle: experiment and theory
• Basic Parameters and Some Precision Tests of the Standard Model