I want to do jet matching with a b-tagged jets in the final state. So as an excise, I generated p p > t b~ j + p p > t b~ j j which works. However when I use 5 flavor scheme, generating pb pb > j b + pb pb > b j j, it failed with the following error: Command "generate_events run_01" interrupted with error: Exception : program /Users/Hongkai/Documents/Software/MG5_aMC_v2_6_5/test10/Events/run_01/PY8_parallelization/run_PY8.sh 0 launch ends with non zero status: 139. Stop all computation Please report this bug on https://bugs.launchpad.net/mg5amcnlo More information is found in '/Users/Hongkai/Documents/Software/MG5_aMC_v2_6_5/test10/run_01_tag_1_debug.log'. Please attach this file to your report. The details are in the attached log files. Is there any way to use 5-flavor scheme to do this sort of matching? Thank you very much!
Hi,
What you did does not make that much sense to me.
1) you need to use a 5 flavor model (like loop_sm-no_bmass) (I bet that you are using a 4 flavor model for the above)
In such model "p" contains automatically the "b" quark.
2) for 5 flavor computation, you also need to include "b" quark in the "j" tag. This is also automatic if you use a 5 flavor model.
3) In 5 flavor computation you also have to set some parameter in the run_card to 5 flavor (again this is automatic if you use 5 flavor)
4) For such computation, you should not specify directly "b" quark in the final state. The reason is that from QCD point of view, since all the quarks are massless, you have the same divergencies for all of them (the mass does not protect the soft and colinear divergencies anymore) and therefore in order to have a meaningfull matching, you have to include all the diagram equivalent to the parton-shower.
So My first advise, is (clearly) to retry with a proper model. If then you still face the same issue. Please contact Stefan Prestel who is responsible for that part of the code in PY8.
Cheers,
Olivier