dipole alpha dependence of massive dipole subtraction broken

[marek]

Running pp->Wbb production with massive b-quarks renders the subtraction dependent on the choice of DIPOLE_ALPHA, or more specifically DIPOLE_ALPHA_FF. All other dipole alphas, dipole kappa and dipole-nf-gluon splittings parameters seem to work:

dal     dal_ii  dal_if  dal_fi  dal_ff  dkap    dgnf            xs (BIRS)

1.                                                              7.76 +- 0.05 pb
0.1                                                             6.86 +- 0.04 pb
0.01                                                            6.55 +- 0.15 pb

1.      0.1                                                     7.76 +- 0.05 pb
1.      0.01                                                    7.76 +- 0.05 pb

1.                              0.1                             6.85 +- 0.05 pb
1.                              0.01                            6.34 +- 0.08 pb

1.              0.1                                             7.72 +- 0.05 pb
1.              0.01                                            7.61 +- 0.12 pb

1.                      0.1                                     7.74 +- 0.05 pb
1.                      0.01                                    7.65 +- 0.12 pb

1.                                              5               7.75 +- 0.05 pb 
1.                                              4               7.76 +- 0.05 pb

1.                                      10.                     7.76 +- 0.05 pb
1.                                      1.                      7.76 +- 0.05 pb
1.                                      0.1                     7.76 +- 0.05 pb            
1.                                      0.01                    7.76 +- 0.05 pb

Curiously, ee->bb seems to work.

dal_ff           xs (BIRS)

1.              -4.229 +- 0.004 pb
0.1             -4.233 +- 0.012 pb
0.01            -4.337 +- 0.118 pb