2004/01/05 by M. Beneke, Μ. Beneke, A. P. Chapovsky +5
Mathematics · Physics and Astronomy · #Effective field theory #Gauge theory #High-Energy Particle Collisions Research #Mathematics #Particle physics theoretical and experimental studies #Perturbation theory (quantum mechanics) #Physics #Propagator #Quantum Chromodynamics and Particle Interactions #Quantum electrodynamics #Quantum mechanics #Scalar (mathematics) #Scattering #Theoretical physics #Yukawa potential #hep-ph
paper · pdf · doi:10.1016/j.nuclphysb.2004.03.016
published as Nucl.Phys. B686 (2004) 205-247 · 45 pages
arxiv created 2004/01/05 · openalex publication_date 2004/04/10 · arxiv updated 2010/04/05 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
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, Gamma. The effective theory allows calculations to be systematically arranged into a series in g2 and Gamma/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 Gamma/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.