The Formula of the Differential Cross Section for the Trident Production

The differential cross section for the lepton trident production in the Coulomb field of nucleus is calculated using a standard technique of quantum electrodynamics. Eight diagrams are taken into account in calculation. Cross section formula in the text is expressed in the form which is most suitable for any type of numerical calculation. Since the formula is expressed in order to make the calculation of individual diagram possible, one can easily evaluate the contribution of certain diagram to cross section at a given experimental geometry. Propagator terms are expressed separately from the others making the modification of this part possible. Numerical calculation of the formula at a given experimental geometry shows a complete agreement with the one of the formula derived independently by Henry.