S-matrix bootstrap for effective field theories: massless pions
Andrea Guerrieri (Instituto de Física Téorica, UNESP, ICTP South American Institute for Fundamental Research, Rua Dr. Bento Teobaldo Ferraz 271, São Paulo, 01140-070, Brazil, School of Physics and Astronomy, Tel Aviv University, Ramat Aviv, Tel Aviv, 69978, Israel); João Penedones (Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), Rte de la Sorge, BSP 728, Lausanne, CH-1015, Switzerland); Pedro Vieira (Perimeter Institute for Theoretical Physics, 31 Caroline St N, Waterloo, ON, N2L 2Y5, Canada, Instituto de Física Téorica, UNESP, ICTP South American Institute for Fundamental Research, Rua Dr. Bento Teobaldo Ferraz 271, São Paulo, 01140-070, Brazil)
We use the numerical S-matrix bootstrap method to obtain bounds on the two leading Wilson coefficients (or low energy constants) of the chiral lagrangian controlling the low-energy dynamics of massless pions. This provides a proof of concept that the numerical S-matrix bootstrap can be used to derive non-perturbative bounds on massless EFTs in more than two spacetime dimensions.