WHIZARD 2 fails to integrate VBF channels correctly

[Juergen Reuter]

The setup for VBF does not integrate with the same result as in WHIZARD 1, Helac or Sherpa. The process is e1, E1 => e1, E1, u, U, d, D, the result from WHIZARD 1 is 0.6521(55) fb. The WHIZARD 2 result however is 0.866(35) fb where the integration is stuck and does not improve at all:

| Initializating integration for process arsch:
| Phase space file 'arsch.phs' not found.
| Generating phase space configuration ...
| ... done.
| ... found 795 phase space channels, collected in 55 groves.
| Phase space: found 1051 equivalences between channels.
| Wrote phase-space configuration file 'arsch.phs'.
| iterations = 5:100000, 25:200000
| Applying user-defined cuts.
| Creating VAMP integration grids:
| Using phase-space channel equivalences.
| 100000 calls, 795 channels, 14 dimensions, 12 bins, stratified = T
| Integrating process 'arsch':
|=============================================================================|
| It      Calls  Integral[fb]  Error[fb]   Err[%]    Acc  Eff[%]   Chi2 N[It] |
|=============================================================================|
   1     100000  5.7038854E-01  9.58E-02   16.80   53.13*   1.21
   2     100000  5.4088309E-01  5.46E-02   10.09   31.90*   0.78
   3     100000  6.9953138E-01  6.56E-02    9.38   29.66*   0.24
   4     100000  9.0424999E-01  1.75E-01   19.33   61.12    0.17
^[[1;5C   5     100000  8.3137084E-01  1.26E-01   15.17   47.97*   0.05
|-----------------------------------------------------------------------------|
   5     500000  6.3176528E-01  3.60E-02    5.69   40.26    0.05    2.30   5
|-----------------------------------------------------------------------------|
   6     200000  8.3751280E-01  1.54E-01   18.34   82.00    0.02
   7     200000  8.7231558E-01  1.45E-01   16.60   74.25*   0.02
   8     200000  8.2172036E-01  4.00E-02    4.87   21.78*   0.01
   9     200000  8.4897070E-01  3.68E-02    4.33   19.36*   0.01
  10     200000  8.6302096E-01  3.54E-02    4.10   18.32*   0.01
  11     200000  8.6603706E-01  3.53E-02    4.08   18.23*   0.02
  12     200000  8.6603852E-01  3.53E-02    4.08   18.23*   0.03
  13     200000  8.6604215E-01  3.53E-02    4.08   18.23*   0.02
  14     200000  8.6608253E-01  3.53E-02    4.08   18.23*   0.00
  15     200000  8.6612555E-01  3.53E-02    4.08   18.23*   0.01
  16     200000  8.6612643E-01  3.53E-02    4.08   18.23*   0.04
  17     200000  8.6612643E-01  3.53E-02    4.08   18.23*   0.02
  18     200000  8.6612645E-01  3.53E-02    4.08   18.23*    NaN
  19     200000  8.6612647E-01  3.53E-02    4.08   18.23*    NaN

I attach the corresponding SINDARIN input file as well as the WHIZARD 1 input and output files.

[Juergen Reuter]

W1 output

[Juergen Reuter]

Process definition

[Juergen Reuter]

WHIZARD 1 cut file

[Juergen Reuter]

WHIZARD 1 input file

[Juergen Reuter]

WHIZARD 2 SINDARIN file