The elastic I = 1/2, s- and p-wave kaon-pion scattering amplitudes are calculated using a single ensemble of anisotropic lattice QCD gauge field configurations with Nf = 2+1 flavors of dynamical Wilson-clover fermions at mπ = 230MeV. A large spatial extent of L = 3.7fm enables a good energy resolution while partial wave mixing due to the reduced symmetries of the finite volume is treated explicitly. The p-wave amplitude is well described by a Breit–Wigner shape with parameters mK⁎/mπ = 3.808(18) and gBWKKπ = 5.33(20) which are insensitive to the inclusion of d-wave mixing and variation of the s-wave parametrization. An effective range description of the near-threshold s-wave amplitude yields mπα0 = –0.353(25).

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Published in Nuclear Physics B, v. 932, p. 29-51.

© 2018 The Author(s). Published by Elsevier B.V.

This is an open access article published under the CC BY license (https://creativecommons.org/licenses/by/4.0/).

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Funded by SCOAP3.

This work was supported by the U.S. National Science Foundation under award PHY-1613449. Computing resources were provided by the Extreme Science and Engineering Discovery Environment (XSEDE) under grant number TG-MCA07S017. XSEDE is supported by National Science Foundation grant number ACI-1548562.