Radiative zeros and extra neutral gauge bosons at lepton-hadron colliders.

Abstract

We consider the process ${e}^{\ifmmode\pm\else\textpm\fi{}}$p\ensuremath{\rightarrow}${e}^{\ifmmode\pm\else\textpm\fi{}}$\ensuremath{\gamma}X. In the first section, we look for radiative zeros and find that they are absent in ${e}^{\mathrm{\ensuremath{-}}}$p collisions but possibly observable in ${e}^{+}$p collisions. In the second section we investigate the effects of the exchange of an extra neutral gauge boson on the process at hand. We find that, given appropriate cuts and using expected luminosities at the DESY ep collider HERA, a 2-standard-deviation effect could arise from a light neutral gauge boson. Z' masses up to \ensuremath{\sim}300 GeV/${c}^{2}$ could be probed at the 1-standard-deviation level.