Negative constraints when generating SMEFTatNLO events with version 3.0.4-qcdonly

Bug #1918942 reported by matteo maltoni on 2021-03-12
This bug affects 1 person
Affects Status Importance Assigned to Milestone
marco zaro

Bug Description

Hi MadGraph experts,

I tried to generate events for the process p p > w+ w- w+ [QCD] using the SMEFTatNLO model. The version I used is the 3.0.4-qcdonly one. I got the following error:

Error detected in "generate p p > w+ w- w+ [QCD]"
write debug file MG5_debug
If you need help with this issue please contact us on
str :
 Automatic process-order determination lead to negative constraints:
 QED: 9, QCD: -6
 Please specify the coupling orders from the command line.

However, the error doesn't show up if I specify the coupling orders explicitly, like this:

generate p p > w+ w- w+ QCD=2 QED=3 [QCD]

Since I know that this version is still under developement, I thought that maybe this is important to mention.

Here below, you can find the debug file:

set group_subprocesses Auto
set ignore_six_quark_processes False
set low_mem_multicore_nlo_generation False
set complex_mass_scheme False
set include_lepton_initiated_processes False
set gauge unitary
set loop_optimized_output True
set loop_color_flows False
set max_npoint_for_channel 0
set default_unset_couplings 99
set max_t_for_channel 99
set zerowidth_tchannel True
set nlo_mixed_expansion True
import model sm
define p = g u c d s u~ c~ d~ s~
define j = g u c d s u~ c~ d~ s~
define l+ = e+ mu+
define l- = e- mu-
define vl = ve vm vt
define vl~ = ve~ vm~ vt~
import model SMEFTatNLO
define p = 21 2 4 1 3 -2 -4 -1 -3 5 -5 # pass to 5 flavors
define j = p
generate p p > w+ w- w+ [QCD]
Traceback (most recent call last):
  File "/home/matteo/Scrivania/3.0.4-qcdonly/madgraph/interface/", line 1544, in onecmd
    return self.onecmd_orig(line, **opt)
  File "/home/matteo/Scrivania/3.0.4-qcdonly/madgraph/interface/", line 1493, in onecmd_orig
    return func(arg, **opt)
  File "/home/matteo/Scrivania/3.0.4-qcdonly/madgraph/interface/", line 278, in do_generate
    return self.cmd.do_generate(self, line, *args, **opts)
  File "/home/matteo/Scrivania/3.0.4-qcdonly/madgraph/interface/", line 4699, in do_generate
    self.do_add(" ".join(args))
  File "/home/matteo/Scrivania/3.0.4-qcdonly/madgraph/interface/", line 229, in do_add
    return self.cmd.do_add(self, line, *args, **opts)
  File "/home/matteo/Scrivania/3.0.4-qcdonly/madgraph/interface/", line 522, in do_add
    raise MadGraph5Error('\nAutomatic process-order determination lead to negative constraints:\n' + \
Automatic process-order determination lead to negative constraints:
QED: 9, QCD: -6
Please specify the coupling orders from the command line.
                          MadGraph5_aMC@NLO Options
        complex_mass_scheme : False
    default_unset_couplings : 99
                      gauge : unitary
         group_subprocesses : Auto
  ignore_six_quark_processes : False
  include_lepton_initiated_processes : False
           loop_color_flows : False
      loop_optimized_output : True
  low_mem_multicore_nlo_generation : False
     max_npoint_for_channel : 0
          max_t_for_channel : 99
        nlo_mixed_expansion : True
               stdout_level : 10 (user set)
         zerowidth_tchannel : True

                         MadEvent Options
     automatic_html_opening : True
                    nb_core : None
        notification_center : True
                   run_mode : 2

                      Configuration Options
                        OLP : MadLoop
         auto_convert_model : False
                auto_update : 7
         cluster_local_path : None
           cluster_nb_retry : 1
              cluster_queue : None (user set)
         cluster_retry_wait : 300
               cluster_size : 100
      cluster_status_update : (600, 30)
          cluster_temp_path : None
               cluster_type : condor
                    collier : None (user set)
               cpp_compiler : None
             crash_on_error : False
               delphes_path : ./Delphes
                 eps_viewer : None
        exrootanalysis_path : ./ExRootAnalysis
              f2py_compiler : None
          f2py_compiler_py2 : None
          f2py_compiler_py3 : None
                    fastjet : None (user set)
           fortran_compiler : None
                      golem : None (user set)
                 hepmc_path : None (user set)
                  hwpp_path : None (user set)
                     lhapdf : /home/matteo/Scrivania/3.0.4-qcdonly/HEPTools/lhapdf6_py3/bin/lhapdf-config (user set)
                 lhapdf_py2 : None
                 lhapdf_py3 : /home/matteo/Scrivania/3.0.4-qcdonly/HEPTools/lhapdf6_py3/bin/lhapdf-config (user set)
          madanalysis5_path : None (user set)
           madanalysis_path : ./MadAnalysis
  mg5amc_py8_interface_path : None (user set)
                      ninja : /home/matteo/Scrivania/3.0.4-qcdonly/HEPTools/lib (user set)
        output_dependencies : external
                   pineappl : pineappl
            pythia-pgs_path : ./pythia-pgs
               pythia8_path : None (user set)
                    samurai : None
               syscalc_path : ./SysCalc
                    td_path : ./td
                text_editor : None
                thepeg_path : None (user set)
                    timeout : 60
                web_browser : None

Changed in mg5amcnlo:
assignee: nobody → marco zaro (marco-zaro)
marco zaro (marco-zaro) wrote :

Hi Matteo,

thanks for reporting the bug.
Indeed, one was getting negative constraints because the coupling hierarchy of QCD and QED was hardcoded to be 1 and 2 respectively.
Instead, for the SMEFTatNLO model, the hierarchy is 2,4.
It has been fixed in the 3.0.4-qcdonly branch, at rev 996

Please let us know if this work for you.


Changed in mg5amcnlo:
status: New → Fix Committed
matteo maltoni (matteo-maltoni) wrote :

Hi Marco,

Thank you for your answer.

It seems to me that it's working now, the diagrams that it generated for the process are the ones I expected.

Please let me know if you need any other check by my side.



Changed in mg5amcnlo:
status: Fix Committed → Fix Released
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