Final State Radiation¶

Along with computing decay spectra, hazma is able to compute final state radiation spectra from decays of off-shell mediators (scalar, psuedo-scalar, vector or axial-vector.) The relavent diagrams for such processes are

Scalar mediator

Vector mediator

Computing the matrix elements squared of these diagrams (including diagrams with the photon attached to the other fermion leg) and integrating over all variables except the photon energy yields \(d\sigma(M^*\to\mu^{+}\mu^{-}\gamma)/dE\). To compute \(dN/dE\), we divide \(d\sigma(M^*\to\mu^{+}\mu^{-}\gamma)/dE\) by \(\sigma(M^*\to\mu^{+}\mu^{-})\).