gg into 4 leptons

Asked by Giacomo Magni on 2020-05-19

I'm trying to simulate that process:

     import model SMEFTatNLO_U2_2_U3_3_cG_4F_LO_UFO-NLO
     generate g g > mu- vm~ e+ ve [noborn=QCD] QED=4 NP=0 @1
     add process g g > mu+ vm e- ve~ [noborn=QCD] QED=4 NP=0 @2
     output myfolder
     launch myfolder

Everything goes fine, except for this warning:

 ^[[1;34mWARNING: Channel G1//data/theorie/gmagni/ATLAS_WW/gg_WW_SMlimit_massless_NLO_ATLAScut/SubProcesses/P2_gg_lvllvl has a very low efficiency of unweighting. Might not be possible to reach target ^[[0m

The simulation goes on but then I got this error:

INFO: Refine results to 100000
INFO: Generating 100000.0 unweighted events.
INFO: Effective Luminosity 1491346.36418 pb^-1
INFO: need to improve 2 channels
Current estimate of cross-section: 0.077110859531 +- 0.000209939353442
INFO: Idle: 0, Running: 2, Completed: 0 [ current time: 21h21 ]
INFO: Idle: 1, Running: 1, Completed: 1 [ 3s ]
^[[1;34mWARNING: float division by zero ^[[0m
^[[1;34mWARNING: float division by zero ^[[0m
INFO: Idle: 0, Running: 0, Completed: 4 [ 3.1s ]
float division by zero
Cluster Error detected. Do you want to clean the queue? ("c"=continue the run anyway) [^[[4my^[[0m, n, c]
^[[1mThe answer to the previous question is not set in your input file^[[0m
^[[1mUse y value^[[0m

The log file reports:

Traceback (most recent call last):
  File "/data/theorie/gmagni/ATLAS_WW/tmp/madgraph/interface/", line 1515, in onecmd
    return self.onecmd_orig(line, **opt)
  File "/data/theorie/gmagni/ATLAS_WW/tmp/madgraph/interface/", line 1464, in onecmd_orig
    return func(arg, **opt)
  File "/data/theorie/gmagni/ATLAS_WW/tmp/madgraph/interface/", line 2469, in do_generate_events
    self.run_generate_events(switch_mode, args)
  File "/data/theorie/gmagni/ATLAS_WW/tmp/madgraph/interface/", line 6963, in new_fct
    original_fct(obj, *args, **opts)
  File "/data/theorie/gmagni/ATLAS_WW/tmp/madgraph/interface/", line 2529, in run_generate_events
    self.exec_cmd('refine %s' % nb_event, postcmd=False)
  File "/data/theorie/gmagni/ATLAS_WW/tmp/madgraph/interface/", line 1544, in exec_cmd
    stop = Cmd.onecmd_orig(current_interface, line, **opt)
  File "/data/theorie/gmagni/ATLAS_WW/tmp/madgraph/interface/", line 1464, in onecmd_orig
    return func(arg, **opt)
  File "/data/theorie/gmagni/ATLAS_WW/tmp/madgraph/interface/", line 3508, in do_refine
  File "/data/theorie/gmagni/ATLAS_WW/tmp/madgraph/interface/", line 5552, in monitor
    self.cluster.wait(self.me_dir, update_status, update_first=update_first)
  File "/data/theorie/gmagni/ATLAS_WW/tmp/madgraph/various/", line 2807, in worker
    returncode = exe(*arg, **opt)
  File "/data/theorie/gmagni/ATLAS_WW/tmp/madgraph/madevent/", line 1465, in combine_iteration
    n_target_combined = (needed_event-nunwgt) / efficiency
ZeroDivisionError: float division by zero

I'm running on multicore mode on a desktop.
What can I do to fix this?

Thank you for your help,

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You should have more precise information in

Without looking at such log file, it seems to be either a numerical issue or a pure model issue



Giacomo Magni (gmagni) said : #2

Hi Olivier,
yes something was wrong in /SubProcesses/P2_gg_lvllvl/G1 because there is no .lhe file.

I attached you the link to the log file.

The result.dat file reports:

    0.23007E-02 0.19861E-03 0.19861E-03 2 113861683 9 2 0.86930E+03 0.39260E+05 0.23007E-02 0.0 0.0 0

And the input_app.txt:

        1000 1 1 !Number of events and max and min iterations
   0.02 !Accuracy
  -2 !Grid Adjustment 0=none, 2=adjust
  1 !Suppress Amplitude 1=yes
  1 !Helicity Sum/event 0=exact

Thank you very much for your help.


G1 seems fine actually.

By the way which technical cut did you use to kill the 0 pt for the W in this channel?
If you do not put cut on the PT of the W this is likely divergent.

This might be related to your issue actually.



Giacomo Magni (gmagni) said : #4

so that may be the issue, I set only:

ptl 10
etal 2.5


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