[Madgraph] setting of W mass does not work

[Zehvogel]

Setting the mass for the Z works, as does setting the width for the W, but setting the W mass in the same does not work and produces a warning. I have no experience with Madgraph (or much Generator experience in general) but after googling a bit it looks like Madgraph always recalculates MW itself from MZ, aEWM1 and gf.

So k4gen should probably do something different when a user tries to set the W mass than now :)

set MZ 91.1876
INFO: modify param_card information BLOCK mass with id (23,) set to 91.1876 
set WZ 2.4952
INFO: modify param_card information BLOCK decay with id (23,) set to 2.4952 
set MW 80.379
WARNING: invalid set command MW 80.379  
set WW 2.085
INFO: modify param_card information BLOCK decay with id (24,) set to 2.085 

[apricePhy]

Hi, The problem is setting consistent EW schemes across all generators is not that trivial and has to be approached delicately. For example, MG is very strict in what the user can and cannot set. So to overcome this for testing, we choose to replicate the MG scheme in the other generators, which requires setting MW. Work is ongoing to implement a scheme setter, which would hopefully avoid messages like the above.