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arXiv · 2008.03035

Scattering of two and three physical pions at maximal isospin from lattice QCD

Matthias Fischer·Bartosz Kostrzewa·Liuming Liu·Fernando Romero-López·Martin Ueding·Carsten Urbach
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Abstract

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.

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Matthias Fischer, Bartosz Kostrzewa, Liuming Liu, Fernando Romero-López, Martin Ueding, Carsten Urbach. 2020-08-07. Scattering of two and three physical pions at maximal isospin from lattice QCD. https://doi.org/10.1140/epjc/s10052-021-09206-5

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