$K pi$ scattering and the $K^*(892)$ resonance in 2+1 flavor QCD

In this project, we will compute the form factors relevant for $B to K^*(to K pi)ell^+ell^-$ decays. To map the finite-volume matrix elements computed on the lattice to the infinite-volume $B to K pi$ matrix elements, the $K pi$ scattering amplitude needs to be determined using Luschers method. Here we present preliminary results from our calculations with $2+1$ flavors of dynamical clover fermions. We extract the $P$-wave scattering phase shifts and determine the $K^*$ resonance mass and the $K^* K pi$ coupling for two different ensembles with pion masses of $317(2)$ and $178(2)$ MeV.