Possible generation of $\pi$-condensation in a free space by collisions between photons and protons

Abstract

A sharply peaked structure is found in the angular distribution of emitted $\pi^+$ mesons from the photon-proton collisions. It offers a possible way for generating a $\pi^+$-condensation in free space. To make the stimulated emission of $\pi^+$-mesons efficient, a ring resonator is designed.