Production of W+W- + jets

Asked by lenzip on 2020-06-18

Dear Experts,
I would like to produce W+W- + jets with FxFx merging with jet multiplicity ideally up to 3, or whatever is the maximum achievable.

I am setting up the gridpack production with simple WW production with no jets with the cards below (*) (planning to decay the Ws with madspin), buy I get error in (**) on the process initiated by bs:
Can you help me understand what I am doing wrong?
Many thanks in advance
Giulio (CMS)

(*)
proc_card:
import model loop_sm-no_b_mass

define p = p b b~
define j = j b b~

define ell+ = e+ mu+ ta+
define ell- = e- mu- ta-

generate p p > w+ w- / h [QCD] @0
#add process p p > w+ w- j / h[QCD] @1
#add process p p > w+ w- j j / h [QCD] @2
#add process p p > w+ w- j j j / h [QCD] @3

output WWTo2L2Nu_0123j_5f_FXFX -nojpeg

run_card:
#***********************************************************************
# MadGraph5_aMC@NLO *
# *
# run_card.dat aMC@NLO *
# *
# This file is used to set the parameters of the run. *
# *
# Some notation/conventions: *
# *
# Lines starting with a hash (#) are info or comments *
# *
# mind the format: value = variable ! comment *
#***********************************************************************
#
#*******************
# Running parameters
#*******************
#
#***********************************************************************
# Tag name for the run (one word) *
#***********************************************************************
  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
 292200 = 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
 .true. = reweight_PDF ! reweight to get PDF uncertainty
 292201 = PDF_set_min ! First of the error PDF sets
 292302 = PDF_set_max ! Last of the error PDF sets
#***********************************************************************
# 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 *
#***********************************************************************
  20 = 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
#***********************************************************************

(**)
INFO: Compiling P0_uux_wpwm_no_h...
INFO: Compiling P0_ddx_wpwm_no_h...
INFO: Compiling P0_bbx_wpwm_no_h...
INFO: Compiling P0_uxu_wpwm_no_h...
INFO: Compiling P0_dxd_wpwm_no_h...
INFO: Compiling P0_bxb_wpwm_no_h...
INFO: P0_bxb_wpwm_no_h done.
INFO: P0_dxd_wpwm_no_h done.
INFO: P0_ddx_wpwm_no_h done.
INFO: P0_uxu_wpwm_no_h done.
INFO: P0_bbx_wpwm_no_h done.
INFO: P0_uux_wpwm_no_h done.
INFO: Checking test output:
INFO: P0_uux_wpwm_no_h
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-05)
INFO: P0_ddx_wpwm_no_h
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-05)
INFO: P0_bbx_wpwm_no_h
INFO: Result for test_ME:
INFO: Passed.
INFO: Result for test_MC:
INFO: Passed.
INFO: Result for check_poles:
Error detected in "launch -n pilotrun"
write debug file /afs/cern.ch/work/l/lenzip/generators/genproductions/bin/MadGraph5_aMCatNLO/WWTo2L2Nu_0123j_5f_FXFX/WWTo2L2Nu_0123j_5f_FXFX_gridpack/work/processtmp/pilotrun_tag_1_debug.log
If you need help with this issue please contact us on https://answers.launchpad.net/mg5amcnlo
aMCatNLOError : Poles do not cancel, run cannot continue
quit

Question information

Language:
English Edit question
Status:
Answered
For:
MadGraph5_aMC@NLO Edit question
Assignee:
marco zaro Edit question
Last query:
2020-06-18
Last reply:
2020-06-18

This is not possible in 5 flavor due to the presence of resonances in the real (the top).
The Plugin MadSTR can be an option, but you need to check the paper to see if that plugin is compatible with FxFx.
If you want to use that plugin, I can assign this question to the associated author.

Cheers,

Olivier

lenzip (lenzip) said : #2

Dear Olivier,
Thanks for your answer.
Two follow-ups:
- is +4 jets achievable, or up to which multiplicity at NLO can I
reasonably go?
- I am not aware of what MadSTR is, if you can assign my question to the
author I would be glad.
Thanks
Giulio

On 18/06/20 15:35, Olivier Mattelaer wrote:
> Your question #691384 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/691384
>
> Status: Open => Answered
>
> Olivier Mattelaer proposed the following answer:
> This is not possible in 5 flavor due to the presence of resonances in the real (the top).
> The Plugin MadSTR can be an option, but you need to check the paper to see if that plugin is compatible with FxFx.
> If you want to use that plugin, I can assign this question to the associated author.
>
> Cheers,
>
> Olivier
>

marco zaro (marco-zaro) said : #3

Hi,
MadSTR is a plugin for the treatment of resonances which appear at NLO (see https://arxiv.org/abs/1907.04898, sect 5 for details)

For your case, I do not think it is a viable option, because it is supposed to only subtract resonances that appear in the NLO correction.
So for example if you compute
p p > w+ w-
It will subtract the top resonance in the real emission g b > w+ w- b
However, when you consider the sample with one extra jet
p p > w+ w- j
MadSTR will not identify resonances at the LO.

Now, in principle, since the top never appears in the final state, you should be able to run keeping WT !=0 and using the complex-mass scheme. However, you will have the tw contribution in the 1-jet sample, and the ttbar one in the two-jet sample. The presence of resonances will further complicate the integration of the process, and needs to be dealt with care when matching to the shower, in general (see e.g https://arxiv.org/abs/1603.01178). Also, I don't know if FxFx works with resonances

So, in the end, I think the best and simplest way is to use the 4FS.

Let me know if you need further help or clarifications.

Best wishes,

Marco

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