Systematics module running even though use_syst=False

[Cyril Becot]

Hey mg5amc folks,

We're trying to generate the following process and are seeing several puzzling things :

import model sm-no_b_mass
generate p p > w+{0} w+{0} j j QED=4 QCD=0, w+ > l+ vl @1
add process p p > w-{0} w-{0} j j QED=4 QCD=0, w- > l- vl~ @1

This is done using mg5amc v2.7.3. We generate first a gridpack for this process - and there everything seems fine. As I don't have lhapdf on my computer, I switched off the systematics module (use_syst = False in the run card attached).

Then we move to the event generation (with ./run.sh 5000 1), and got the error message below. Despite the error message, I do get the output LHE file with the requested number of events (at least on my own computer - I'll open another ticket about that in a minute). And I see no other errors/warnings. Of course, in the run_card of the gridpack use_syst is still set to False, so we are wondering why the error is triggered and whether it's not a bug

Kind regards
Cyril

Traceback (most recent call last):
  File "./madevent/bin/gridrun", line 86, in <module>
    cmd_line = cmd_interface.GridPackCmd(me_dir=root_path, nb_event=args[0], seed=args[1], gran=args[2])
  File "/home/cbecot/Travail/StandardModel/SameSignWW/MCStudies/PlayingWithMG_Pola/PrepareChatWithDresden/evt_gen/madevent/bin/internal/madevent_interface.py", line 6417, in __init__
    self.launch(nb_event, seed)
  File "/home/cbecot/Travail/StandardModel/SameSignWW/MCStudies/PlayingWithMG_Pola/PrepareChatWithDresden/evt_gen/madevent/bin/internal/madevent_interface.py", line 6530, in launch
    postcmd=False,printcmd=False)
  File "/home/cbecot/Travail/StandardModel/SameSignWW/MCStudies/PlayingWithMG_Pola/PrepareChatWithDresden/evt_gen/madevent/bin/internal/extended_cmd.py", line 1544, in exec_cmd
    stop = Cmd.onecmd_orig(current_interface, line, **opt)
  File "/home/cbecot/Travail/StandardModel/SameSignWW/MCStudies/PlayingWithMG_Pola/PrepareChatWithDresden/evt_gen/madevent/bin/internal/extended_cmd.py", line 1464, in onecmd_orig
    return func(arg, **opt)
  File "/home/cbecot/Travail/StandardModel/SameSignWW/MCStudies/PlayingWithMG_Pola/PrepareChatWithDresden/evt_gen/madevent/bin/internal/common_run_interface.py", line 1731, in do_systematics
    raise self.InvalidCmd, "The events was not generated with use_syst=True. Can not evaluate systematics error on this event file."
internal.InvalidCmd: The events was not generated with use_syst=True. Can not evaluate systematics error on this event file.

[Olivier Mattelaer (olivier-mattelaer)]

Thanks for letting me notice that.
The following patch should fix that issue (which is harmless) and will be release within the next version of the code (2.8.2).

Thanks,

Olivier