Beneke, M. and Chapovsky, A. P. and Signer, A. and Zanderighi, G. (2004) 'Effective theory calculation of resonant high-energy scattering.', Nuclear physics B., 686 (1-2). pp. 205-247.
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.
|Keywords:||Modified perturbation-theory, 2-loop propagator integrals, Collinear effective theory, Heavy unstable particles, Effective field-theory, Fermion-loop scheme, W-pair production, Nonfactorizable corrections, Radiative-corrections, Feynman-integrals.|
|Full text:||PDF - Other (416Kb)|
|Publisher Web site:||http://dx.doi.org/10.1016/j.nuclphysb.2004.03.016|
|Record Created:||06 May 2008|
|Last Modified:||05 Aug 2011 16:16|
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