Exotic quark production at DESY HERA energies.

Abstract

In this paper we present a study of the production and decay of exotic heavy quarks in the fermion--mirror-fermion, vector singlet, and vector doublet models. A Monte Carlo final-state reconstruction of events is given for kinematical distributions. At energies reached at DESY HERA we show that exotic quarks in the mass range 100--150 GeV, and with mixing angles of the order of ${\mathrm{sin}}^{2}$\ensuremath{\theta}=0.05, can be clearly dominant over the standard ``top'' quark production. We discuss experimental cuts that can eliminate the ``bottom'' background. We compare the theoretical predictions of the three models above in order to indicate a way to establish the origin of a possible experimental signal of an exotic quark. Even if no such signal is found, HERA can still improve the experimental bounds on exotic objects, although there is some model dependence on the estimates of total cross sections.