Renormalon resummation and exponentiation of soft and collinear gluon radiation in the thrust distribution

Summary, in English

The thrust distribution in e⁺e^- annihilation is calculated exploiting its exponentiation property in the two-jet region t=1-T≪1. We present a general method (DGE) to calculate a large class of logarithmically enhanced terms, using the dispersive approach in renormalon calculus. Dressed Gluon Exponentiation is based on the fact that the exponentiation kernel is associated primarily with a single gluon emission, and therefore the exponent is naturally represented as an integral over the running coupling. Fixing the definition of Λ is enough to guarantee consistency with the exact exponent to next-to-leading logarithmic accuracy. Renormalization scale dependence is avoided by keeping all the logs. Sub-leading logs, that are usually neglected, are factorially enhanced and are therefore important. Renormalization-group invariance as well as infrared renormalon divergence are recovered in the sum of all the logs. The logarithmically enhanced cross-section is evaluated by Borel summation. Renormalon ambiguity is then used to study power corrections in the peak region Qt≳Λ, where the hierarchy between the renormalon closest to the origin (~1/Qt) and others (~1/(Qt)ⁿ) starts to break down. The exponentiated power-corrections can be described by a shape-function, as advocated by Korchemsky and Sterman. Our calculation suggests that the even central moments of the shape-function are suppressed. Good fits are obtained yielding α_s^MS(M_Z)=0.110±0.001, with a theoretical uncertainty of ~5%.

• Author: Einan Gardi; Johan Rathsman
• Publishing year: 2001-08-20
• Language: English
• Pages: 123-182
• Publication/Series: Nuclear Physics B
• Volume: 609
• Issue: 1-2
• Links: http://dx.doi.org/10.1016/S0550-3213(01)00284-X
• Document type: Journal article
• Publisher: North-Holland
• Topic: Subatomic Physics
• Keywords: 12.38.Cy; 13.87.-a
• Status: Published
• ISBN/ISSN/Other: ISSN: 0550-3213