Australian Natl Univ, Res Sch Phys Sci, Dept Theoret Phys, Canberra, ACT 2601, Australia
; CCAST, World Lab, Ctr Theoret Phys, Beijing 100080, Peoples R China
; Acad Sinica, Inst High Energy Phys, Beijing 100039, Peoples R China
; Guangxi Normal Univ, Dept Phys, Guilin 54100, Peoples R China
; Sch Zhejiang Light Ind, Dept Phys, Hangzhou 310015, Peoples R China
A hybrid quark-hadron model is used to describe high energy pion-alpha scattering. The parameters for the quark regime are determined by fitting pion-proton elastic scattering data. The energy dependence of both the first and the second diffraction minima in the pion-alpha elastic scattering cross section is predicted. It is found that the quark degrees of freedom in pion-nucleon interaction plays a significant role, particularly at high momentum transfer.