2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/179662We compute total cross sections for charm and bottom photoproduction at HERA energies, and discuss the relevant theoretical uncertainties. In particular we discuss the problems arising from the small-$x$ region, the uncertainties in the gluon parton density, and the uncertainties in the hadronic component of the cross section. Total electroproduction cross sections, calculated in the Weizsäcker-Williams approximation, are also given.20 pages, Latex and style files tarred, gzipped and uuencoded; 10 postscript figures appended at the end (look for %%%%figures) as tarred, gzipped and uuencoded fileHigh Energy Physics - Phenomenologytext