%0 Journal Article
%T Scattering of two and three physical pions at maximal isospin from lattice QCD Extended Twisted Mass Collaboration
%A Fischer, M.
%A Kostrzewa, B.
%A Liu, L. M.
%A Romero-Lopez, F.
%A Ueding, M.
%A Urbach, C.
%J European Physical Journal C
%D 2021
%V 81
%N 5
%I Springer
%@ 1434-6044
%G English
%F Fischer_etal2021
%O WOS:000680425500003
%O exported from refbase (https://references.ific.uv.es/refbase/show.php?record=4900), last updated on Wed, 11 Aug 2021 09:00:48 +0000
%X We present the first direct N-f = 2 lattice QCD computation of two- and three-pi(+) 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 M(pi)a(0) = -0.0481(86) 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.
%R 10.1140/epjc/s10052-021-09206-5
%U https://arxiv.org/abs/2008.03035
%U https://doi.org/10.1140/epjc/s10052-021-09206-5
%P 436 - 19pp