The gridpack seems sometimes very large in size? Can I improve on this?

The MadGraph code (and also the gridpack) has a directory for each subprocess contributing to a process. For process with many external legs, for example when using matching, the number of subprocesses can be very large. This makes the size of the gridpack large. There are two ways to reduce the size of the gridpacks:

Dynamic Libraries

Each of the subprocess directories in the gridpack has a separate madevent executable. They are build from the subprocess dependent part in that particular subprocess directory as well as an independent part containing the MODEL files, HELAS and integration routines. This is included in each executable via a set of Libraries. By default they are linked statically to the madevent executables, such that each of these executables can be used independently from the libraries.

However, when running over the grid, the use of dynamic libraries is recommended. Instead of compiling with

./bin/compile,

the command

./bin/compile dynamic

can be used to create dynamic libraries and link them appropriately. This reduces the size of the gridpack, but generates exactly the same events as with static libraries.

For more technical details on setting up and running the gridpacks, see here.

The Chopper

TheChopper-pl is a perl script that removes subprocesses of which the sum contributes less then a given percentage to the total cross section. It can be found in the

./madevent/bin/

directory of the gridpack. For more details on how to use it click on this link.

-- Main.RikkertFrederix - 02 Mar 2009