Regular Article - Theoretical Physics
Scattering of two and three physical pions at maximal isospin from lattice QCD
Extended Twisted Mass Collaboration
Helmholtz-Institut für Strahlen- und Kernphysik, University of Bonn, 53115, Bonn, Germany
2 Bethe Center for Theoretical Physics, University of Bonn, 53115, Bonn, Germany
3 High Performance Computing and Analytics Lab, University of Bonn, 53115, Bonn, Germany
4 Institute of Modern Physics, Chinese Academy of Sciences, 730000, Lanzhou, China
5 University of Chinese Academy of Sciences, 100049, Beijing, China
6 Instituto de Física Corpuscular, Universitat de València and CSIC, 46980, Paterna, Spain
Accepted: 2 May 2021
Published online: 20 May 2021
We present the first direct lattice QCD computation of two- and three- scattering quantities that includes an ensemble at the physical point. We study the quark mass dependence of the two-pion phase shift, and the three-particle interaction parameters. We also compare to phenomenology and chiral perturbation theory (ChPT). In the two-particle sector, we observe good agreement to the phenomenological fits in s- and d-wave, and obtain at the physical point from a direct computation. In the three-particle sector, we observe reasonable agreement at threshold to the leading order chiral expansion, i.e. a mildly attractive three-particle contact term. In contrast, we observe that the energy-dependent part of the three-particle quasilocal scattering quantity is not well described by leading order ChPT.
© The Author(s) 2021
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