MadGraph5_aMC@NLO

poles do not cancel in ee > bbww

Asked by Fabian Bach

Using aMC@NLO, I tried to compute the total NLO cross section for the process e+ e- > w+ b w- b~ near the ttbar threshold. To that end, I just did

generate e+ e- > w+ b w- b~ [QCD]
output ee_wbwb
launch

in the MG5 shell. I set the beam structure to '0' and each beam energy to '174'. I alwasy get

Error detected in "launch auto "
write debug file /home/fbach/tools/MG5_aMC_v2_2_1/ee_wbwb/run_01_tag_1_debug.log
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aMCatNLOError : Poles do not cancel, run cannot continue

I already tried both setting fixed_order=ON/OFF and the setting W width to zero as well as non-zero. Moreover, I already found ticket #256309 and tried to hack the 'energy = ' line as advocated there, but to no avail. The reasoning of #251302 should not be an issue here, as the tree level process is always well-defined EW, right?

Question information

Language:
English Edit question
Status:
Expired
For:
MadGraph5_aMC@NLO Edit question
Assignee:
marco zaro Edit question
Last query:
Last reply:
Revision history for this message
Fabian Bach (fabian-bach) said : 		#1

The debug.log file:

launch auto
Traceback (most recent call last):
  File "/home/fbach/tools/MG5_aMC_v2_2_1/madgraph/interface/extended_cmd.py", line 879, in onecmd
    return self.onecmd_orig(line, **opt)
  File "/home/fbach/tools/MG5_aMC_v2_2_1/madgraph/interface/extended_cmd.py", line 872, in onecmd_orig
    return func(arg, **opt)
  File "/home/fbach/tools/MG5_aMC_v2_2_1/madgraph/interface/amcatnlo_run_interface.py", line 1189, in do_launch
    self.compile(mode, options)
  File "/home/fbach/tools/MG5_aMC_v2_2_1/madgraph/interface/amcatnlo_run_interface.py", line 3749, in compile
    self.check_tests(test, this_dir)
  File "/home/fbach/tools/MG5_aMC_v2_2_1/madgraph/interface/amcatnlo_run_interface.py", line 3761, in check_tests
    return self.parse_check_poles_log(pjoin(dir, '%s.log' % test))
  File "/home/fbach/tools/MG5_aMC_v2_2_1/madgraph/interface/amcatnlo_run_interface.py", line 3796, in parse_check_poles_log
    raise aMCatNLOError('Poles do not cancel, run cannot continue')
aMCatNLOError: Poles do not cancel, run cannot continue
Value of current Options:
              web_browser : None
              text_editor : nano
        cluster_temp_path : None
       group_subprocesses : False
             syscalc_path : None
            cluster_queue : None
         madanalysis_path : None
                   lhapdf : lhapdf-config
ignore_six_quark_processes : False
                    pjfry : None
    loop_optimized_output : True
    cluster_status_update : (600, 30)
   automatic_html_opening : False
                    gauge : unitary
               hepmc_path : None
             pythia8_path : None
                hwpp_path : None
                  amcfast : amcfast-config
       cluster_retry_wait : 300
      output_dependencies : external
          pythia-pgs_path : None
                 mg5_path : /home/fbach/tools/MG5_aMC_v2_2_1
                  td_path : None
             delphes_path : None
              thepeg_path : None
             cluster_type : condor
      exrootanalysis_path : None
         fortran_compiler : None
                  nb_core : 4
                      OLP : MadLoop
              auto_update : 7
         cluster_nb_retry : 1
                 applgrid : applgrid-config
               eps_viewer : None
                  timeout : 60
                  fastjet : fastjet-config
                    golem : /home/fbach/tools/lib
      complex_mass_scheme : False
             cpp_compiler : None
             stdout_level : 20
                 run_mode : 2

Revision history for this message
Launchpad Janitor (janitor) said : 		#2

This question was expired because it remained in the 'Open' state without activity for the last 15 days.

Revision history for this message
marco zaro (marco-zaro) said : 		#3

Dear Fabian,
sorry for the delay in the answer, we have somehow lost your question.
You need to activate the complex mass scheme in order to generate consistently this process at NLO.
Just type
set complex_mass_scheme

before the generate and output command.
This should solve your problem.
All the best!

Marco