RECOLA: REcursive Computation of One-Loop Amplitudes

We present the Fortran95 program Recola for the perturbative computation of next-to-leading-order transition amplitudes in the Standard Model of particle physics. The code provides numerical results in the ’t Hooft–Feynman gauge. It uses the complex-mass scheme and allows for a consistent isolation of resonant contributions. Dimensional regularization is employed for ultraviolet and infrared singularities, with the alternative possibility of treating collinear and soft singularities in mass regularization. Recola supports various renormalization schemes for the electromagnetic and a dynamical Nf-flavour scheme for the strong coupling constant. The calculation of next-to-leading-order squared amplitudes, summed over spin and colour, is supported as well as the computation of colour- and spin-correlated leading-order squared amplitudes needed in the dipole subtraction formalism.