Higher-order tree-level amplitudes in the nonlinear sigma model

A bstract We present a generalisation of the flavour-ordering method applied to the chiral nonlinear sigma model with any number of flavours. We use an extended Lagrangian with terms containing any number of derivatives, organised in a power-counting hierarchy. The method allows diagrammatic computa...

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Bibliographic Details
Published in:	The journal of high energy physics 2019-11, Vol.2019 (11), p.1-46, Article 74
Main Authors:	Bijnens, Johan, Kampf, Karol, Sjö, Mattias
Format:	Article
Language:	eng
Subjects:	Amplitudes Chiral Lagrangians Classical and Quantum Gravitation Effective Field Theories Elementary Particles Field theory Flavors Fysik High energy physics Kinematics Legs Methods Natural Sciences Naturvetenskap Physical Sciences Physics Physics and Astronomy Quantum Field Theories Quantum Field Theory Quantum Physics Quantum theory Regular Article - Theoretical Physics Relativity Theory Scattering Amplitudes Spon- taneous Symmetry Breaking String Theory Subatomic Physics Subatomär fysik Symmetry
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Summary:	A bstract We present a generalisation of the flavour-ordering method applied to the chiral nonlinear sigma model with any number of flavours. We use an extended Lagrangian with terms containing any number of derivatives, organised in a power-counting hierarchy. The method allows diagrammatic computations at tree-level with any number of legs at any order in the power-counting. Using an automated implementation of the method, we calculate amplitudes ranging from 12 legs at leading order, O ( p 2 ), to 6 legs at next-to- next-to-next-to-leading order, O ( p 8 ). In addition to this, we generalise several properties of amplitudes in the nonlinear sigma model to higher orders. These include the double soft limit and the uniqueness of stripped amplitudes.
ISSN:	1029-8479 1029-8479