Can HERA see aneu→ecsignal of a virtual leptoquark?

Virtual leptoquarks could be detected at the DESY ep collider HERA through some nonstandard effects. Here we explore the possibility that virtual leptoquarks could be discovered via eu→ec scattering, assuming an integrated luminosity of 200 ${\mathrm{pb}}^{\mathrm{-}1}$ and charm identification efficiency of 1%. We study the implications of low-energy data for the leptoquark couplings and find that the most relevant bound for the HERA cross sections comes from inclusive c→${\mathit{e}}^{+}$ ${\mathit{e}}^{\mathrm{-}}$+any. This bound implies that the eu→ec cross sections for virtual leptoquarks are just too small for observation of the signal. With an improvement by a factor of ∼2 on the luminosity or on the charm identification it could be possible to see virtual leptoquarks with maximum couplings up to ∼1.5–2 TeV. However, the prospects for discovering the virtual particles if their couplings are somewhat below present bounds are very dim. We point out that this cross section could be very large for leptoquarks lighter than HERA’s kinematical limit, and if such a leptoquark is discovered we recommend searching for a possible eu→ec signal. Our results may also serve as an update on the maximum cross sections for leptoquark-mediated eu→μc scattering.