Higher-order tree-level amplitudes in the nonlinear sigma model
| Autor: | Bijnens, Johan, Kampf, Karol, Sjö, Mattias |
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| Rok vydání: | 2019 |
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| Druh dokumentu: | Working Paper |
| DOI: | 10.1007/JHEP11(2019)074 |
| Popis: | 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, $\mathcal{O}(p^2)$, to 6 legs at next-to-next-to-next-to-leading order, $\mathcal{O}(p^8)$. 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. Comment: 47 pages, the file flavour-order.pdf contains the expressions for two more amplitudes and the diagrams for all calculated ones |
| Databáze: | arXiv |
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