The Lambda filter is used in the new generation of MC sample in order to improve the efficiency and save the space of disk.
The filter is based on the StMCFIlter.
The Lambda filter request the event includes one Lambda or anti-Lambda at least.
The event generated from pythia goes into the filter and then will be stored in the output file (fzd file) if passes the filter.
The power of the filter is about 0.01 and varying in each hard pT and Lambda pT interval.
The time of running bfc chain is saved a lot.

In the kumac file, the command 

exec StRoot/StMCFilter/loadlibs.kumac

gfilt Lambda

is used for calling the filter.