Single leptoquark production associated with hard photon emission in ep collisions at high energies

In this paper we consider single leptoquark resonance production associated with the emission of a hard photon. We have obtained analytical formulæ for differential and total cross sections for the cases of scalar and vector leptoquarks. We have found that in reactions with scalar leptoquarks there is no photon radiation in some directions depending on the leptoquark electric charge (the radiative amplitude zero — the RAZ effect). For vector leptoquarks the exact RAZ is present only in the case of Yang-Mills coupling. We propose to use the RAZ effect to determine the types of leptoquarks. We conclude also that this effect opens a possibility to measure the leptoquark anomalous magnetic moment.