Abstract
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=230 MeV. A large spatial extent of L=3.7 fm 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 gK⁎KπBW=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 mπa0=−0.353(25).
Highlights
Elastic Kπ scattering amplitudes are essential to several current frontiers in the phenomenology of the Standard Model of particle physics
The theoretical formalism to extract form factors correctly treating the unstable nature of the K∗ is well known [4, 5] and requires the elastic p-wave Kπ scattering amplitude calculated in this work
In this work 22 finite-volume Kπ energies calculated from an Nf = 2 + 1 lattice QCD simulation are employed to determine the I = 1/2, S = 1 elastic s- and p-wave Kπ scattering amplitudes
Summary
Elastic Kπ scattering amplitudes are essential to several current frontiers in the phenomenology of the Standard Model of particle physics. Existing lattice calculations of these form factors do not treat the K∗ as a unstable particle [2,3]. The theoretical formalism to extract form factors correctly treating the unstable nature of the K∗ is well known [4, 5] and requires the elastic p-wave Kπ scattering amplitude calculated in this work. The amplitudes calculated in this work may provide information on the quark-mass dependence of these resonance poles and confront expectations from chiral effective theories [7,8,9,10,11,12]
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