K pi scattering for isospin 1/2 and 3/2 in lattice QCD

TL;DR

This paper uses lattice QCD to simulate K pi scattering in different isospin channels, extracting phase shifts and identifying resonance states, providing insights consistent with experimental data.

Contribution

It presents a novel lattice QCD simulation of K pi scattering in both s-wave and p-wave channels for isospins 1/2 and 3/2, including resonance identification.

Findings

Qualitative agreement with experimental phase shifts.

Identification of resonance states like K_0^*(1430) and K*(892).

Extraction of scattering lengths and effective ranges.

Abstract

We simulate K pi scattering in s-wave and p-wave for both isospins I=1/2, 3/2 using quark-antiquark and meson-meson interpolating fields. We extract the elastic phase shifts delta at several values of the K-pi relative momenta. The resulting phases exhibit qualitative agreement with the experimental phases in all four channels. We express the s-wave phase shifts near threshold in terms of the scattering length and the effective range. Our K pi system has zero total momentum and is simulated on a single ensemble with two dynamical quarks, so results apply for mpi=266 MeV and mK=552 MeV in our simulation. The backtracking contractions in both I=1/2 channels are handled by the use of Laplacian-Heavyside smeared quarks within the distillation method. Elastic phases are extracted from the energy levels using Luscher's relations. In all four channels we observe the expected K(n)pi(-n) scattering states, which are shifted due to the interaction. In both attractive I=1/2 channels we observe additional states that are related to resonances; we attribute them to K_0^*(1430) in s-wave and K*(892), K*(1410) and K*(1680) in p-wave.