t-channel unitarity and photon cross sections Original Research Article

We analyse the consequences of t-channel unitarity for the photon hadronic cross sections. We show that γ(∗)p and γ(∗)γ(∗) elastic amplitudes must include the complex-j plane singularities associated with hadronic elastic amplitudes, and give the characteristics of possible new singularities. We also show that several different models of hadronic total cross sections can be used to predict the LEP data from the HERA measurements.