Contour-improved versus fixed-order perturbation theory in hadronic τ decays
نویسندگان
چکیده
منابع مشابه
Contour-improved versus fixed-order perturbation theory in hadronic τ decays
The hadronic decay rate of the τ lepton serves as one of the most precise determinations of the QCD coupling αs. The dominant theoretical source of uncertainty at present resides in the seeming disparity of two approaches to improving the perturbative expansion with the help of the renormalisation group, namely fixed-order and contourimproved perturbation theory. In this work it is demonstrated...
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The determination of αs from hadronic τ decays is revisited, with a special emphasis on the question of higher-order perturbative corrections and different possibilities of resumming the perturbative series with the renormalisation group: fixed-order (FOPT) vs. contour-improved perturbation theory (CIPT). The difference between these approaches has evolved into a systematic effect that does not...
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We consider the determination of αs from τ hadronic decays, by investigating the contourimproved (CI) and the fixed-order (FO) renormalization group summations in the frame of a new perturbation expansion of QCD, which incorporates in a systematic way the available information about the divergent character of the series. The new expansion functions, which replace the powers of the coupling, are...
متن کاملOn the determination of αs from hadronic τ decays with contour-improved, fixed order and renormalon-chain perturbation theory
One of the largest theoretical uncertainties assigned to the strong coupling constant αs as determined from hadronic tau decays stems from the differences in the results for Fixed Order Perturbation Theory (FOPT), Contour Improved Perturbation Theory (CIPT) and Renormalon Chain Perturbation Theory (RCPT). It is often argued that the three methods differ in the treatment of higher orders only an...
متن کاملR(s) and hadronic τ-Decays in Order α4 s
Three important physical observables, namely, the ratio R(s) = σ(e e→hadrons) σ(e+e−→μ+μ−) , the hadronic decay rate of the Z-boson and the semileptonic branching ratio of the τ -lepton are expressed through the vector and axial-vector current correlators (see, e. g. reviews [4,5]). Perturbative QCD provides reliable predictions for these correlators in the continuum, i.e. sufficiently above th...
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ژورنال
عنوان ژورنال: Journal of High Energy Physics
سال: 2005
ISSN: 1029-8479
DOI: 10.1088/1126-6708/2005/09/058