Twist-3 contributions to $\gamma \gamma \to {\pi }^{+}{\pi }^{-},K^{+}{K}^{-}$ processes in perturbative QCD approach

Cong Wang, Jun-Kang He, Ming-Zhen Zhou

As one of the simplest hadronic processes, $\gamma \gamma \to M^{+}{M}^{-}$ ($M=\pi ,K$) could be a good testing ground for our understanding of the perturbative and nonperturbative structu…