Single top production at HERA in the Standard Model and its minimal supersymmetric extension Original Research Article

The H1 Collaboration at the DESY electron–proton collider HERA has observed, in photoproduction and neutral-current deep-inelastic scattering, an unexpected excess of events with isolated leptons and missing transverse momentum, especially at large values of hadronic transverse momentum—a signature typical for single top-quark production. This observation is being substantiated in the HERA II run. Motivated by this, we evaluate the cross section of single top-quark photo- and electroproduction both in the Standard Model and its minimal supersymmetric extension, considering both minimal and non-minimal flavour-violation scenarios in the latter case.