QCD Analysis of hadronic tau lepton decays
Diploma paper written at the Johannes Gutenberg-Universitaet Mainz.
hep-ph↗
arXiv subjects
F. Krajewski
Publications and source records attributed to F. Krajewski.
Determination of the strange quark mass from Cabibbo-suppressed tau decays with resummed perturbation theory in an effective scheme
We present an analysis of the m_s^2-corrections to Cabibbo-suppressed tau lepton decays employing contour improved resummation within an effective scheme which is an essential new feature as compared to previous analyses. The whole perturbative QCD dynamics of the tau-system is described by the beta-function of the effective coupling constant and by two gamma-functions for the effective mass parameters of the strange quark in different spin channels. We analyze the stability of our results with regard to high-order terms in the perturbative expansion of the renormalization group functions. A numerical value for the strange quark mass in the MS scheme is extracted m_s(M_τ)=130\pm 27_{exp}\pm 9_{th} MeV. After running to the scale 1 GeV this translates into m_s(1 GeV)=176 \pm 37_{exp}\pm 13_{th} MeV.
hep-ph↗
Strong coupling constant from $τ$ decay within renormalization scheme invariant treatment
We extract a numerical value for the strong coupling constant α_s from the τ-lepton decay rate into nonstrange particles. A new feature of our procedure is the explicit use of renormalization scheme invariance in analytical form in order to perform the actual analysis in a particular renormalization scheme. For the reference coupling constant in the \MSsch-scheme we obtain α_s(M_τ)= 0.3184 \pm 0.0060_{exp} which corresponds to \al_s(M_Z)= 0.1184 \pm 0.0007_{exp} \pm 0.0006_{hq mass}. This new numerical value is smaller than the standard value from $τ$-data quoted in the literature and is closer to \al_s(M_Z)-values obtained from high energy experiments.
hep-ph↗
Asymptotic structure of perturbative series for $τ$ lepton decay observables: $m_s^2$ corrections
In a previous paper we performed an analysis of asymptotic structure of perturbation theory series for semileptonic $τ$-lepton decays in massless limit. We extend our analysis to the Cabibbo suppressed $ΔS=1$ decay modes of the $τ$ lepton. In particular we address the problem of $m_s^2$ corrections to theoretical formulas. The properties of the asymptotic behavior of the finite order perturbation theory series for the coefficient functions of the $m_s^2$ corrections are studied.
hep-ph↗
Asymptotic structure of perturbative series for tau lepton observables
We analyze tau lepton decay observables, namely moments of the hadronic spectral density in the finite energy interval (0,M_τ), within finite order perturbation theory including α_s^4 corrections. The start of asymptotic growth of perturbation theory series is found at this order in a scheme invariant manner. We establish the ultimate accuracy of finite order perturbation theory predictions and discuss the construction of optimal observables.
hep-ph↗