MadGraph5_aMC@NLO

Command "generate_events " interrupted with error

Asked by Andre Sznajder

Hi,
I am using the Madgraph VERSION 5.2.2.3 to generate the process :

define p = g u c d s b u~ c~ d~ s~ b~
define j = p
define l+ = e+ mu+
define l- = e- mu-
define vl = ve vm
define vl~ = ve~ vm~
generate p p > l+ l- l+ vl j j QED=6 QCD=0 @ 1
add process p p > l+ l- l- vl~ j j QED=6 QCD=0 @ 2

The generate_events process failed with the error bellow. How can I find out what's going on and what's the offending cut ?
The only cuts I have changed are ptj>20 , ptl>10 , etaj < 6.5 , etal < 2.5 , deltaeta > 2.0 , mll>4 and mjj>300 !

...
STOP 1
Command "generate_events " interrupted with error:
MadEventError : Error detected Stop running: Error: grouping of subprocesses not consistent with setcuts.f. Either change your cuts and/or turn grouping of subprocesses off.

Please report this bug on https://bugs.launchpad.net/madgraph5
More information is found in '/uscms/home/sznajder/work/generators/MG5_aMC_v2_2_2/WZ_QED6_QCD0_lllv/run_01_tag_1_debug.log'.
Please attach this file to your report.
quit
INFO:

Cheers,
Andre

Question information

Language:
English Edit question
Status:
Answered
For:
MadGraph5_aMC@NLO Edit question
Assignee:
Rikkert Frederix Edit question
Last query:
Last reply:
Revision history for this message
Rikkert Frederix (frederix) said : 		#1

Dear Andre,

It's probably the invariant mass cut on the leptons. According to the code, this should be applied only on *same-flavour* lepton pairs (with opposite charge). Since the grouping of the subprocesses combines same and opposite flavour leptons, the code cannot apply this cut consistently. You either have to remove this cut (and replace it with another one to remove the possible IR singularity) or to turn the grouping of the subprocesses off. Or you could also generate the processes with all the lepton flavours separately, i.e.,

generate p p > e+ e- e+ ve j j qed=6 qcd=0 @1
add process p p > e+ e- mu+ vm j j qed=6 qcd=0 @2
add process p p > mu+ mu- e+ ve j j qed=6 qcd=0 @3
etc. etc.

by specifying the @1, @2, @3 etc, the code will not (try to) group these processes together.

Best regards,
Rikkert

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