PowhegControl: adding feature for MadSpin decays (22.6) - AGENE-2165
This is a manual sweep of !58950 (merged) which did the same changes to 21.6.
This MR does a few modifications in PowhegControl related to MadSpin, as mentioned in AGENE-2165.
If the decays are done with MadSpin, using a model that contains "ckm" or "CKM" in its name, then the decay branching ratios for top and W are removed from the param_card before running MadSpin, so that MadSpin will recalculate them at LO using the model, possibly with special ckm matrix parameters.
If such a model is used, the Wolfenstein parameters block is written in the param_card. The four parameters can be set by the user in the joboption. The default values are:
PowhegConfig.Wolfenstein_lambda = 2.257000e-01
PowhegConfig.Wolfenstein_A = 8.140000e-01
PowhegConfig.Wolfenstein_rho = 1.350000e-01
PowhegConfig.Wolfenstein_eta = 3.490000e-01These correspond to the default values in the sm-zeromass_ckm model.
Finally, I removed the setting of widths and BRs for -6 and -24 in the param_card (whatever the model is), because MadSpin anyway always does the same for particle and anti-particle. So having two values for top and anti-top is confusing (even if we were always setting the same value), and useless.