V+jets NLO Madspin crash in gridpack

Asked by Andreas on 2018-02-12


I am encountering a problem when trying to produce events from a gridpack that makes use of MadSpin.
I run 2.6.0 and the process is W+jets @ NLO with "decay V > q q" (also using bias weighting). Cards are at [1].

The initial run completes fine, but when I try to run from the gridpack, I get a crash (Logs at [2] and [3]).
Specifically, the crash happens on line 644 of madspin_interface.py, on this command:

    decay2['path'] = decay2['path'].replace(generate_all.path_me, self.options['ms_dir'])

It appears that this happens because one of the decay dicts in madspin.pkl has these contents:

    decay2 = {'matrix_element': None, 'finals': None, 'br': 1.1102230246251565e-16, 'base_order': None, 'path': None, 'decay_tag': None, 'decay_struct': None}

So basically 0 BR, but all other attributes set to None. If I add a simple check to avoid this crash, everything runs fine:

    if( not decay2['path'] ):
        decay2['path'] = decay2['path'].replace(generate_all.path_me, self.options['ms_dir'])

I also verified that the wanted decays of W->qq are present (printing path, branching and tag):

./madspingrid/full_me/SubProcesses/P2_uxcx_wmguxsx_wm_dux 0.3163456 ('wm_dux',)
./madspingrid/full_me/SubProcesses/P2_uxcx_wmguxsx_wm_dcx 0.01690461 ('wm_dcx',)
./madspingrid/full_me/SubProcesses/P2_uxcx_wmguxsx_wm_sux 0.01690412 ('wm_sux',)
./madspingrid/full_me/SubProcesses/P2_uxcx_wmguxsx_wm_scx 0.3163456 ('wm_scx',)
./madspingrid/full_me/SubProcesses/P2_uxcx_wmguxsx_wm_bux 3.802001e-06 ('wm_bux',)
./madspingrid/full_me/SubProcesses/P2_uxcx_wmguxsx_wm_bcx 0.0005602024 ('wm_bcx',)

Is it safe to just skip the pathologic decay or is this indicative of an underlying problem that needs to be understood?



[1] https://github.com/cmantill/genproductions/tree/mg26x/bin/MadGraph5_aMCatNLO/cards/production/13TeV/WJetsToQQ_5f_NLO_FXFX_bias
[2] Log of gridpack generation: http://cmantill.web.cern.ch/cmantill/gridpack_generationWJetsbias.log
[3] Log showing the error: http://cmantill.web.cern.ch/cmantill/cmsgrid_tag_1_debug.log

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