Browsing by Author "Helset, Andreas"
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Item New factorization relations for nonlinear sigma model amplitudes(American Physical Society, 2019-02-15) Bjerrum-Bohr, Niels Emil Jannik; Gomez, Humberto; Helset, AndreasWe obtain novel factorization identities for nonlinear sigma model amplitudes using a new integrand in the Cachazo-He-Yuan double-cover prescription. We find that it is possible to write very compact relations using only longitudinal degrees of freedom. We discuss implications for on shell recursion. © 2019 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the »https://creativecommons.org/licenses/by/4.0/» Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP 3 .Item Scattering equations and a new factorization for amplitudes. Part II. Effective field theories(Springer Verlag, 2019-05-01) Gomez, Humberto; Helset, AndreasWe continue the program of extending the scattering equation framework by Cachazo, He and Yuan to a double-cover prescription. We discuss how to apply the double-cover formalism to effective field theories, with a special focus on the non-linear sigma model. A defining characteristic of the double-cover formulation is the emergence of new factorization relations. We present several factorization relations, along with a novel recursion relation. Using the recursion relation and a new prescription for the integrand, any non-linear sigma model amplitude can be expressed in terms of off-shell three-point amplitudes. The resulting expression is purely algebraic, and we do not have to solve any scattering equation. We also discuss soft limits, boundary terms in BCFW recursion, and application of the double-cover prescription to other effective field theories, like the special Galileon theory. © 2019, The Author(s).