Single dilepton production ate+e−,eγ, and γγ colliders

We calculate the cross sections for the single production of doubly charged dileptons, both scalar and vector, at ${\mathit{e}}^{+}$ ${\mathit{e}}^{\mathrm{-}}$, eγ, and γγ colliders at √s =500 GeV and 1 TeV. The eγ mode is by far the most promising—dileptons whose coupling is as weak as ∼${10}^{\mathrm{-}4}$ ${\mathrm{\alpha }}_{\mathrm{em}}$ can be observed, for masses virtually up to the kinematic limit. Dileptons of mass up to √s can also be seen in ${\mathit{e}}^{+}$ ${\mathit{e}}^{\mathrm{-}}$ and γγ colliders, for couplings of order ${\mathrm{\alpha }}_{\mathrm{em}}$. In all three colliders, most of the cross section comes from events in which the only particles detected are ${\mathit{e}}^{\mathrm{-}}$ ${\mathit{e}}^{\mathrm{-}}$ (or ${\mathrm{\mu }}^{\mathrm{-}}$ ${\mathrm{\mu }}^{\mathrm{-}}$ or ${\mathrm{\tau }}^{\mathrm{-}}$ ${\mathrm{\tau }}^{\mathrm{-}}$), the decay products of the dilepton, yielding an unmistakable experimental signature.