MadGraph5_aMC@NLO

Unable to produce WZ events at NLO with semilep decays using the 5f scheme

Asked by Ankita Mehta on 2022-08-22

Dear experts,

We are trying to produce WZ events for the semileptonic decay channel where the W (Z) boson decays leptonically (hadronically). MG version 2.6.5 is used with madspin to handle Z decays.
This works flawlessly with 4f scheme but breaks down when we switch to 5f scheme.
The first error we got was “Poles do not cancel run cannot continue” and circumvented this by bypassing the check using the settings from FKS_params.dat. But then we end up in the situation where the pilot run stops after complaining about “widths of final state particles (e.g. top) have been set to 0 in the param_card.dat” We suspect the issue is due to top interference and but removing diagrams with top does not help resolve this.
Pasted blow are the process, run, madspin and FKS_params cards that we used for the generation and the produced log file and for the sake of completeness these are available here as well:
https://anmehta.web.cern.ch/anmehta/WVsemilep/WmToLNuWpToQQ_5f_amcatnloFxFx/

Could you please take a look and suggest a way out and please let us know if further information is needed from our end.

Best,
Meng & Ankita

==================process card==================
import model loop_sm-no_b_mass
define ell+ = e+
define ell- = e-
define vl = ve
define vl~ = ve~
generate p p > ell- vl~ w+ [QCD] @0
add process p p > ell- vl~ w+ j [QCD] @1

output WmToLNuWpToQQ_5f_amcatnloFxFx -nojpeg

==================madspin card==================
set ms_dir ./madspingrid
set Nevents_for_max_weigth 250 # number of events for the estimate of the max. weight
set max_weight_ps_point 400 # number of PS to estimate the maximum for each event
set max_running_process 1
decay w+ > j j
decay w- > j j
launch
==================FKS_params==================
#IRPoleCheckThreshold
-1.0d0
#PrecisionVirtualAtRunTime
-1d0
#NHelForMCoverHels
4
#VirtualFraction
1.0d0
#MinVirtualFraction
0.005d0
########run card#####
#***********************************************************************
tag_1 = run_tag ! name of the run
#***********************************************************************
# Number of events (and their normalization) and the required *
# (relative) accuracy on the Xsec. *
# These values are ignored for fixed order runs *
#***********************************************************************

  1500 = nevents ! Number of unweighted events requested
0.001 = req_acc ! Required accuracy (-1=auto determined from nevents)
   -1 = nevt_job! Max number of events per job in event generation.
                 ! (-1= no split).
average = event_norm ! Normalize events to sum or average to the X sect.
#***********************************************************************
# Number of points per itegration channel (ignored for aMC@NLO runs) *
#***********************************************************************
0.01 = req_acc_FO ! Required accuracy (-1=ignored, and use the
                     ! number of points and iter. below)
# These numbers are ignored except if req_acc_FO is equal to -1
5000 = npoints_FO_grid ! number of points to setup grids
4 = niters_FO_grid ! number of iter. to setup grids
10000 = npoints_FO ! number of points to compute Xsec
6 = niters_FO ! number of iter. to compute Xsec
#***********************************************************************
# Random number seed *
#***********************************************************************
     0 = iseed ! rnd seed (0=assigned automatically=default))
#***********************************************************************
# Collider type and energy *
#***********************************************************************
    1 = lpp1 ! beam 1 type (0 = no PDF)
    1 = lpp2 ! beam 2 type (0 = no PDF)
6500 = ebeam1 ! beam 1 energy in GeV
6500 = ebeam2 ! beam 2 energy in GeV
#***********************************************************************
# PDF choice: this automatically fixes also alpha_s(MZ) and its evol. *
#***********************************************************************
lhapdf = pdlabel ! PDF set
$DEFAULT_PDF_SETS = lhaid ! if pdlabel=lhapdf, this is the lhapdf number
#***********************************************************************
# Include the NLO Monte Carlo subtr. terms for the following parton *
# shower (HERWIG6 | HERWIGPP | PYTHIA6Q | PYTHIA6PT | PYTHIA8) *
# WARNING: PYTHIA6PT works only for processes without FSR!!!! *
#***********************************************************************
  PYTHIA8 = parton_shower
#***********************************************************************
# Renormalization and factorization scales *
# (Default functional form for the non-fixed scales is the sum of *
# the transverse masses of all final state particles and partons. This *
# can be changed in SubProcesses/set_scales.f) *
#***********************************************************************
F = fixed_ren_scale ! if .true. use fixed ren scale
F = fixed_fac_scale ! if .true. use fixed fac scale
91.188 = muR_ref_fixed ! fixed ren reference scale
91.188 = muF1_ref_fixed ! fixed fact reference scale for pdf1
91.188 = muF2_ref_fixed ! fixed fact reference scale for pdf2
#***********************************************************************
# Renormalization and factorization scales (advanced and NLO options) *
#***********************************************************************
F = fixed_QES_scale ! if .true. use fixed Ellis-Sexton scale
91.188 = QES_ref_fixed ! fixed Ellis-Sexton reference scale
1 = muR_over_ref ! ratio of current muR over reference muR
1 = muF1_over_ref ! ratio of current muF1 over reference muF1
1 = muF2_over_ref ! ratio of current muF2 over reference muF2
1 = QES_over_ref ! ratio of current QES over reference QES
#***********************************************************************
# Reweight flags to get scale dependence and PDF uncertainty *
# For scale dependence: factor rw_scale_up/down around central scale *
# For PDF uncertainty: use LHAPDF with supported set *
#***********************************************************************
.true. = reweight_scale ! reweight to get scale dependence
  0.5 = rw_Rscale_down ! lower bound for ren scale variations
  2.0 = rw_Rscale_up ! upper bound for ren scale variations
  0.5 = rw_Fscale_down ! lower bound for fact scale variations
  2.0 = rw_Fscale_up ! upper bound for fact scale variations
$DEFAULT_PDF_MEMBERS = reweight_PDF ! reweight to get PDF uncertainty
#***********************************************************************
# Merging - WARNING! Applies merging only at the hard-event level. *
# After showering an MLM-type merging should be applied as well. *
# See http://amcatnlo.cern.ch/FxFx_merging.htm for more details. *
#***********************************************************************
3 = ickkw ! 0 no merging, 3 FxFx merging
#***********************************************************************
#
#***********************************************************************
# BW cutoff (M+/-bwcutoff*Gamma) *
#***********************************************************************
15 = bwcutoff
#***********************************************************************
# Cuts on the jets *
# Jet clustering is performed by FastJet.
# When matching to a parton shower, these generation cuts should be *
# considerably softer than the analysis cuts. *
# (more specific cuts can be specified in SubProcesses/cuts.f) *
#***********************************************************************
   1 = jetalgo ! FastJet jet algorithm (1=kT, 0=C/A, -1=anti-kT)
1.0 = jetradius ! The radius parameter for the jet algorithm
  15 = ptj ! Min jet transverse momentum
  -1 = etaj ! Max jet abs(pseudo-rap) (a value .lt.0 means no cut)
#***********************************************************************
# Cuts on the charged leptons (e+, e-, mu+, mu-, tau+ and tau-) *
# (more specific gen cuts can be specified in SubProcesses/cuts.f) *
#***********************************************************************
   0 = ptl ! Min lepton transverse momentum
  -1 = etal ! Max lepton abs(pseudo-rap) (a value .lt.0 means no cut)
   0 = drll ! Min distance between opposite sign lepton pairs
   0 = drll_sf ! Min distance between opp. sign same-flavor lepton pairs
   0 = mll ! Min inv. mass of all opposite sign lepton pairs
  4 = mll_sf ! Min inv. mass of all opp. sign same-flavor lepton pairs
#***********************************************************************
# Photon-isolation cuts, according to hep-ph/9801442 *
# When ptgmin=0, all the other parameters are ignored *
#***********************************************************************
  10 = ptgmin ! Min photon transverse momentum
  -1 = etagamma ! Max photon abs(pseudo-rap)
0.4 = R0gamma ! Radius of isolation code
1.0 = xn ! n parameter of eq.(3.4) in hep-ph/9801442
1.0 = epsgamma ! epsilon_gamma parameter of eq.(3.4) in hep-ph/9801442
.true. = isoEM ! isolate photons from EM energy (photons and leptons)
#***********************************************************************
# Maximal PDG code for quark to be considered a jet when applying cuts.*
# At least all massless quarks of the model should be included here. *
#***********************************************************************
5 = maxjetflavor
#***********************************************************************
================== excerpt from the log file==========================
INFO: Using LHAPDF v6.2.1 interface for PDFs
INFO: Compiling source...
INFO: ...done, continuing with P* directories
INFO: Compiling directories...
INFO: Compiling on 14 cores
INFO: Compiling P0_uux_emvexwp...
INFO: Compiling P0_ddx_emvexwp...
INFO: Compiling P0_uxu_emvexwp...
INFO: Compiling P0_dxd_emvexwp...
INFO: Compiling P0_bbx_emvexwp...
INFO: Compiling P1_gu_emvexwpu...
INFO: Compiling P0_bxb_emvexwp...
INFO: Compiling P1_gd_emvexwpd...
INFO: Compiling P1_gux_emvexwpux...
INFO: Compiling P1_gdx_emvexwpdx...
INFO: Compiling P1_gb_emvexwpb...
INFO: Compiling P1_gbx_emvexwpbx...
INFO: Compiling P1_ug_emvexwpu...
INFO: Compiling P1_uux_emvexwpg...
INFO: P0_ddx_emvexwp done.
INFO: Compiling P1_dg_emvexwpd...
INFO: P0_uxu_emvexwp done.
INFO: Compiling P1_ddx_emvexwpg...
INFO: P0_bxb_emvexwp done.
INFO: Compiling P1_uxg_emvexwpux...
INFO: P0_dxd_emvexwp done.
INFO: Compiling P1_uxu_emvexwpg...
INFO: P0_uux_emvexwp done.
INFO: Compiling P1_dxg_emvexwpdx...
INFO: P0_bbx_emvexwp done.
INFO: Compiling P1_dxd_emvexwpg...
INFO: P1_uux_emvexwpg done.
INFO: Compiling P1_bg_emvexwpb...
INFO: P1_gd_emvexwpd done.
INFO: Compiling P1_bbx_emvexwpg...
INFO: P1_gbx_emvexwpbx done.
INFO: Compiling P1_bxg_emvexwpbx...
INFO: P1_gu_emvexwpu done.
INFO: Compiling P1_bxb_emvexwpg...
INFO: P1_gb_emvexwpb done.
INFO: P1_gux_emvexwpux done.
INFO: P1_ug_emvexwpu done.
INFO: P1_gdx_emvexwpdx done.
INFO: P1_dxd_emvexwpg done.
INFO: P1_ddx_emvexwpg done.
INFO: P1_uxu_emvexwpg done.
INFO: P1_uxg_emvexwpux done.
INFO: P1_dg_emvexwpd done.
INFO: P1_dxg_emvexwpdx done.
INFO: P1_bbx_emvexwpg done.
INFO: P1_bxb_emvexwpg done.
INFO: P1_bg_emvexwpb done.
INFO: P1_bxg_emvexwpbx done.
INFO: Checking test output:
INFO: P0_uux_emvexwp
INFO: Result for test_ME:
INFO: Passed.
INFO: Result for test_MC:
INFO: Passed.
INFO: Result for check_poles:
INFO: Poles successfully cancel for 20 points over 20 (tolerance=-1.0e+00)
INFO: P0_ddx_emvexwp
INFO: Result for test_ME:
INFO: Passed.
INFO: Result for test_MC:
INFO: Passed.
INFO: Result for check_poles:
INFO: Poles successfully cancel for 20 points over 20 (tolerance=-1.0e+00)
INFO: P0_uxu_emvexwp
INFO: Result for test_ME:
INFO: Passed.
INFO: Result for test_MC:
INFO: Passed.
INFO: Result for check_poles:
INFO: Poles successfully cancel for 20 points over 20 (tolerance=-1.0e+00)
INFO: P0_dxd_emvexwp
INFO: Result for test_ME:
INFO: Passed.
INFO: Result for test_MC:
INFO: Passed.
INFO: Result for check_poles:
INFO: Poles successfully cancel for 20 points over 20 (tolerance=-1.0e+00)
INFO: P0_bbx_emvexwp
INFO: Result for test_ME:
INFO: Passed.
INFO: Result for test_MC:
INFO: Passed.
INFO: Result for check_poles:
INFO: Poles successfully cancel for 20 points over 20 (tolerance=-1.0e+00)
INFO: P0_bxb_emvexwp
INFO: Result for test_ME:
INFO: Passed.
INFO: Result for test_MC:
INFO: Passed.
INFO: Result for check_poles:
INFO: Poles successfully cancel for 20 points over 20 (tolerance=-1.0e+00)
INFO: P1_gu_emvexwpu
INFO: Result for test_ME:
INFO: Passed.
INFO: Result for test_MC:
INFO: Passed.
INFO: Result for check_poles:
INFO: Poles successfully cancel for 20 points over 20 (tolerance=-1.0e+00)
INFO: P1_gd_emvexwpd
INFO: Result for test_ME:
INFO: Passed.
INFO: Result for test_MC:
INFO: Passed.
INFO: Result for check_poles:
INFO: Poles successfully cancel for 20 points over 20 (tolerance=-1.0e+00)
INFO: P1_gux_emvexwpux
INFO: Result for test_ME:
INFO: Passed.
INFO: Result for test_MC:
INFO: Passed.
INFO: Result for check_poles:
INFO: Poles successfully cancel for 20 points over 20 (tolerance=-1.0e+00)
INFO: P1_gdx_emvexwpdx
INFO: Result for test_ME:
INFO: Passed.
INFO: Result for test_MC:
INFO: Passed.
INFO: Result for check_poles:
INFO: Poles successfully cancel for 20 points over 20 (tolerance=-1.0e+00)
INFO: P1_gb_emvexwpb
INFO: Result for test_ME:
INFO: Output of the failing test:
==== LHAPDF6 USING DEFAULT-TYPE LHAGLUE INTERFACE ====
LHAPDF 6.2.1 loading /cvmfs/cms.cern.ch/slc7_amd64_gcc700/external/lhapdf/6.2.1-pafccj3/share/LHAPDF/NNPDF31_nnlo_as_0118_mc_hessian_pdfas/NNPDF31_nnlo_as_0118_mc_hessian_pdfas_0000.dat
NNPDF31_nnlo_as_0118_mc_hessian_pdfas PDF set, member #0, version 1; LHAPDF ID = 325300
Enter 0 to compute MC/MC(limit)
       1 to compute MC/ME(limit)
       2 to compute ME/ME(limit)
Enter xi_i, y_ij to be used in coll/soft tests
  Enter -2 to generate them randomly
Enter number of tests for soft and collinear limits
A PDF is used, so alpha_s(MZ) is going to be modified
Old value of alpha_s from param_card: 0.11799999999999999
New value of alpha_s from PDF lhapdf : 0.11800208008122040
Give FKS configuration number ("0" loops over all)

=================================================

NEW FKS CONFIGURATION:
FKS configuration number is 1
FKS partons are: i= 7 j= 1
with PDGs: i= 21 j= 21

Enter graph number (iconfig), '0' loops over all graphs
Using random seed offsets: 1 , 11 , 0
with seed 32
Ranmar initialization seeds 10730 9417
tau_min 1 1 : 0.80419E+02 -- 0.17584E+03
tau_min 2 1 : 0.80419E+02 -- 0.17584E+03
tau_min 3 1 : 0.95419E+02 0.95419E+02 0.17584E+03
tau_min 4 1 : 0.80419E+02 -- 0.17584E+03
tau_min 5 1 : 0.80419E+02 -- 0.17584E+03
tau_min 6 1 : 0.80419E+02 -- 0.17584E+03
tau_min 7 1 : 0.80419E+02 -- 0.17584E+03
tau_min 8 1 : 0.80419E+02 -- 0.17584E+03
tau_min 9 1 : 0.80419E+02 -- 0.17584E+03
tau_min 10 1 : 0.80419E+02 -- 0.17584E+03

Soft tests done for (Born) config 1
Failures: 85
Soft test 1 FAILED. Fraction of failures: 0.85

Collinear tests done for (Born) config 1
Failures: 100
Collinear test 1 FAILED. Fraction of failures: 1.00

=================================================

NEW FKS CONFIGURATION:
FKS configuration number is 2
FKS partons are: i= 7 j= 2
with PDGs: i= 21 j= 5