Electroproduction of supersymmetric particles and gauge bosons

The electroproduction of scalar leptons and gauginos at HERA and at supercollider energies is studied. In particular, the channel $\text{ep}\text{→}\text{e}\text{(→}\text{e}\text{+}\text{γ}\text{)}\text{γ}\text{X}$ is analyzed in full detail. The exa analytic expressions for the cross section and the spectrum of the final electron are derived and evaluated for $\text{√s ? 0.15?3}\text{TeV}$ and different values of the scalar electron and photino masses. Since the exact formulae are relatively complicated, simplified expressions in the Weizsäcker-Williams approximation are also given and their accuracy is discussed by comparison with the exact formulae. The standard processes $\text{ep}\text{→}\text{Z}\text{(→ v}\text{v}\text{)}\text{eX and ep}\text{→}\text{W}\text{(→}\text{e}\text{v}\text{)v}\text{X}$ which also lead to one final electron and two invisible particles are considered in parallel. The corresponding cross sections and distributions are discussed in comparison with the supersymmetric signal. The Z⁰ cross section is found to be quite smaller than was reported previously. To clarify this point the Z⁰ production at the leptonic vertex was computed both exactly and in the Weizsäcker-Williams approximation with quite consistent results.