If electron-positron annihilation into fermion-antifermion pairs were only mediated by a virtual photon... more than one answer possible

1. the cross-section would be proportional to the square of the fine structure constant.

2 the cross-section would be inversely proportional to the square of the total center-of-mass energy of the electron-positron pair.

3 the angular distribution of the final state particles would be symmetric in the forward and backward direction.

4 the cross-section would not have a peak at s equal to the mass of the Z boson squared.