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 |
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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 |

Depositing User: | Francis Jayakanth |

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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