I want to calculate the matrix element of Z0 decay into a fermion, antofermion pair given the propagator, vertex element and fermi's golden rule.
But somewthing is going wrong.
First the propagator has a term 1/Mz^2 so
the MatrixElement^2 will go like 1/Mz^4.
but the vertex factor has...
Can somebody help me out? I'm reading about formulas for cross sections for spin1 particles but I don't understand the delta functions, in calculating the 2particle pahse space psi
For example the interaction; A+B -> C+D has the formula;
psi= (2pi)^2 delta(Pa+Pb-Pc-Pd) d3Pc d3Pd / 4EcEd...