Version 2 (modified by 14 years ago) ( diff ) | ,
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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/Nc2 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/Ncn 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/Ncn). 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.
Attachments (2)
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matrix2.f
(21.7 KB
) - added by 14 years ago.
This is an example of a different format for matrix.f that wil allow compilation even for high multiplicities
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nexper.f
(2.2 KB
) - added by 14 years ago.
A routine to generate the next permutation
Download all attachments as: .zip