The complex-mass scheme and unitarity in perturbative quantum field theory

We investigate unitarity within the complex-mass scheme, a convenient universal scheme for perturbative calculations involving unstable particles in quantum field theory which guarantees exact gauge invariance. Since this scheme requires one to introduce complex masses and complex couplings, the Cut...

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Veröffentlicht in:	The European physical journal. C, Particles and fields Particles and fields, 2015-08, Vol.75 (8), p.1-16, Article 377
Hauptverfasser:	Denner, Ansgar, Lang, Jean-Nicolas
Format:	Artikel
Sprache:	eng
Schlagworte:	Analysis Astronomy Astrophysics and Cosmology Collisions (Nuclear physics) Couplings Cutting Elementary Particles Gauge invariance Hadrons Heavy Ions Mathematical analysis Measurement Science and Instrumentation Nuclear Energy Nuclear Physics Physics Physics and Astronomy Quantum Field Theories Quantum Field Theory Quantum theory Regular Article - Theoretical Physics Scalars String Theory
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Beschreibung
Zusammenfassung:	We investigate unitarity within the complex-mass scheme, a convenient universal scheme for perturbative calculations involving unstable particles in quantum field theory which guarantees exact gauge invariance. Since this scheme requires one to introduce complex masses and complex couplings, the Cutkosky cutting rules, which express perturbative unitarity in theories of stable particles, are no longer valid. We derive corresponding rules for scalar theories with unstable particles based on Veltman’s largest-time equation and prove unitarity in this framework.
ISSN:	1434-6044 1434-6052
DOI:	10.1140/epjc/s10052-015-3579-2