Effective theory calculation of resonant high-energy scattering

M. Beneke, A. P. Chapovsky, A. Signer, G. Zanderighi

Research output: Contribution to journalArticlepeer-review

83 Scopus citations

Abstract

Tests of the Standard Model and its hypothetical extensions require precise theoretical predictions for processes involving massive, unstable particles. It is well-known that ordinary weak-coupling perturbation theory breaks down due to intermediate singular propagators. Various pragmatic approaches have been developed to deal with this difficulty. In this paper we construct an effective field theory for resonant processes utilizing the hierarchy of scales between the mass of the unstable particle, M, and its width, Γ. The effective theory allows calculations to be systematically arranged into a series in g2 and Γ/M, and preserves gauge invariance in every step. We demonstrate the applicability of this method by calculating explicitly the inclusive line shape of a scalar resonance in an Abelian gauge-Yukawa model at next-to-leading order in Γ/M and the weak couplings. We also discuss the extension to next-to-next-to-leading order and compute an interesting subset of these corrections.

Original languageEnglish
Pages (from-to)205-247
Number of pages43
JournalNuclear Physics, Section B
Volume686
Issue number1-2
DOIs
StatePublished - 10 May 2004
Externally publishedYes

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