Determination of alpha(s)(M-tau(2)) from improved fixed order perturbation theory

Abbas, Gauhar and Ananthanarayan, B and Caprini, Irinel (2012) Determination of alpha(s)(M-tau(2)) from improved fixed order perturbation theory. In: PHYSICAL REVIEW D, 85 (9).

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Abstract

We revisit the extraction of alpha(s)(M-tau(2)) from the QCD perturbative corrections to the hadronic tau branching ratio, using an improved fixed-order perturbation theory based on the explicit summation of all renormalization-group accessible logarithms, proposed some time ago in the literature. In this approach, the powers of the coupling in the expansion of the QCD Adler function are multiplied by a set of functions D-n, which depend themselves on the coupling and can be written in a closed form by iteratively solving a sequence of differential equations. We find that the new expansion has an improved behavior in the complex energy plane compared to that of the standard fixed-order perturbation theory (FOPT), and is similar but not identical to the contour-improved perturbation theory (CIPT). With five terms in the perturbative expansion we obtain in the (MS) over bar scheme alpha(s)(M-tau(2)) = 0.338 +/- 0.010, using as input a precise value for the perturbative contribution to the hadronic width of the tau lepton reported recently in the literature.

Item Type:	Journal Article
Publication:	PHYSICAL REVIEW D
Publisher:	AMER PHYSICAL SOC
Additional Information:	Copy right for this article belongs to American Physical Society
Keywords:	HADRONIC TAU-DECAYS;RENORMALIZATION-GROUP IMPROVEMENT; QUANTUM CHROMODYNAMICS;SCALE DEPENDENCE;QCD PREDICTIONS; BETA-FUNCTION;LEPTON DECAY
Department/Centre:	Division of Physical & Mathematical Sciences > Centre for High Energy Physics
Date Deposited:	14 Jul 2012 07:08
Last Modified:	14 Jul 2012 07:08
URI:	http://eprints.iisc.ac.in/id/eprint/44693

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