get_amplitude_rcl¶

get_amplitude_rcl(npr, order, colour, hel, pow=None, gs=None)

Extracts a specific contribution to the amplitude of the process with process number npr, according to the values of pow, order, colour and hel.

Parameters: npr (int) – process number order (str) – loop-order of the contribution order = ‘LO’: tree squared amplitude order = ‘NLO’: loop squared amplitude order = ‘NLO-D4’: loop squared amplitude, bare loop contribution order = ‘NLO-CT’: loop squared amplitude, counterterms contribution order = ‘NLO-R2’: loop squared amplitude, rational terms contribution colour (int[l]) – colour structure which is a vector of type integer and length l, where each position in the vector corresponds to one of the l external particles of process npr (ordered as in the process definition). For colourless particles, incoming quarks and outgoing anti-quarks, the corresponding entry in colour must be 0. For all other particles (gluons, outgoing quarks and incoming anti-quarks), the entries must be, without repetition, the positions of the gluons, incoming quarks and outgoing anti-quarks in the process definition. hel (int[l]) – helicity (array) with entries: left-handed fermions/antifermions: -1 right-handed fermions/antifermions: +1 logitudinal vector bosons: 0 transverse vector bosons: -1, +1 scalar particles: 0 pow/gs (int[]) – array with values representing the powers in fundamental couplings in the order as dictated by the model file, e.g. [2, 3] $$\equiv g_\mathrm{s}^2 e^3$$, or, if supported by the model, the power in terms of $$g_\mathrm{s}$$ only (power in $$e$$ is determined automatically from the underlying process) (Ar, Ai) (float, float)