Multi Parton Amplitudes

An effort should now be done to bring v5 towards handling multiparton processes. We are not aiming to a full MadEvent independent solution and we would be already happy if we could build a code that could run in a reasonable time for pp>V+5partons (so to do V+4 jets at NLO), pp>5 partons (so to do 4 jets at NLO). In fact, we are trying to get something working up to 1/Nc^{2_ corrections (included). In this case we could go higher in multiplicity (up to pp> 7 partons so to do pp>6 jets at NLO).}

The main line of optimization concerns multi-gluon amplitudes. At this stage we focus only on these. The reason is simple: once two quark lines are included then any other multi-quark subproc is suppressed in the number of colors and also kinematically (the latter is not a theorem but by experience it is true).

We suggest to proceeed in steps.

First Step : getting a code for pp>X + n gluons exact at all 1/Nc^{n and compiling.}

This should be achieved rather easily, if we don't worry about SPEED (which we will in the next step, of course). Anyway is mandatory to have a code that can do |M|^{2 EXACTLY (at all orders in 1/Nc}n). Note that the current algorithm that gets the color matrix is already able to select powers in 1/Nc so this is not an issue.