Small fraction of unstable PS points

Asked by Josh Kunkle

Hello,

I've generated gridpacks for the process

p p > a a a [QCD] @0 ; p p > a a a j [QCD] @1

using model loop_sm-no_b_mass

and with ickkw = 3 (FXFX merging)

After the processing finished I get a report that includes 30 not rescued unstable points, here is the output

      Summary:
      Process p p > a a a [QCD] @0 ; p p > a a a j [QCD] @1
      Run at p-p collider (6500.0 + 6500.0 GeV)
      Total cross-section: 1.528e+01 +- 3.2e-02 pb
      Number of events generated: 1500
      Parton shower to be used: PYTHIA8
      Fraction of negative weights: 0.16
      Total running time : 893h 11m
  Number of loop ME evaluations (by MadLoop): 2283614
    Stability unknown: 0
    Stable PS point: 2238954
    Unstable PS point (and rescued): 44630
    Unstable PS point (and not rescued): 30
    Only double precision used: 2238954
    Quadruple precision used: 44660
    Initialization phase-space points: 0
    Reduction methods used:
      > CutTools (double precision) 2107218
      > IREGI 131736
      > CutTools (quadruple precision) 44630
      > Not identified (CTModeRun != -1) 30
  Total number of unstable PS point detected: 30 (0.00%)
    Maximum fraction of UPS points in channel processtmp/SubProcesses/P1_dxg_aaadx/GF10 (0.01%)

It points to the log file SubProcesses/P1_dxg_aaadx/GF10/UPS.log and here are the contents,

 ===== EPS # 1 =====
 mu_r = 45.740862420486629
 alpha_S = 0.14866301770815049
 MadLoop return code, pole check and accuracy reported 420 F 1.1236056751862959E-003
 helicity (MadLoop only) 0 1
 1/eps**2 expected from MadFKS= -1.6850084357123357E-011
 1/eps**2 obtained in MadLoop = -2.3714755692699274E-012
 1/eps expected from MadFKS= -8.0535838645496787E-012
 1/eps obtained in MadLoop = -6.9541743892298382E-013
 finite obtained in MadLoop = 2.0706916949898217E-012
 Accuracy estimated by MadLop = 1.1236056751862959E-003
 1 0.486224135151909E+02 0.000000000000000E+00 0.000000000000000E+00 0.486224135151909E+02 0.000000000000000E+00
 2 0.486224135151909E+02 -0.000000000000000E+00 -0.000000000000000E+00 -0.486224135151909E+02 0.000000000000000E+00
 3 0.186576265014998E+02 -0.142453375457708E+01 0.172448514566429E+02 0.697802468395305E+01 0.000000000000000E+00
 4 0.400893010165081E+02 -0.238486955021526E+02 -0.294485358946087E+02 -0.130834059977419E+02 0.000000000000000E+00
 5 0.115673089563457E+02 0.847652843801766E-01 0.110695460224575E+02 -0.335568207594437E+01 0.000000000000000E+00
 6 0.269305905560281E+02 0.251884639723495E+02 0.113413841550823E+01 0.946106338973323E+01 0.000000000000000E+00

I understand from other posts that it is probably OK to use this gridpack, so I post this for your information, but please let me know if not.

Question information

Language:
English Edit question
Status:
Solved
For:
MadGraph5_aMC@NLO Edit question
Assignee:
Valentin Hirschi Edit question
Last query:
Last reply:
Revision history for this message
Valentin Hirschi (valentin-hirschi) said :
#1

Yes this is fine to use your sample given that only 30 PS points were unstable out of 2M.
Thank you for reporting them though.