Consider the interaction ete t (i give the formula for how the interaction rate at a collider depends geometrical cross section of the beams (ii) draw the tree-level feynman diagram for this interaction, clearly labelling all fundamental particles and the initial and final states (iii) list the gauge bosons that may act as propagators at tree-level for this interaction list the gauge bosons that may not act as propagators for this interactions and state why they can not (iv) state how the cross-section and therefore the probability of the interaction depend on the matrix element m. explain how the matrix element is composed, and give the general prop- agator term. state which propagator would dominate at centre-of-mass energies of 1 gev and 90 gev.