math domain error in MG5_aMC_v2_5_0_beta2

[Richard Ruiz]

Hey Folks,

Unsure if you guys caught this already but I found a small typo in the bin/internal/systematics.py script of MG5_aMC_v2_5_0_beta2 for LO processes. I caught this because I am using a model with massless b:

In Line 205-6, the b mass for the model is checked if nonzero and changes the *charm* by mistake:
            if bmass == 0:
                cmass = 4.7
            self.alpsrunner = Alphas_Runner(asmz, nloop, zmass, cmass, bmass)

Consequently, MG spits out the following output :
systematics.py", line 207, in __init__
    self.alpsrunner = Alphas_Runner(asmz, nloop, zmass, cmass, bmass)
  File "/.../MG5_aMC_v2_5_0_beta2/models/model_reader.py", line 264, in __init__
    t = 2 * math.log(bmass/zmass)
ValueError: math domain error

best,
richard

[Olivier Mattelaer (olivier-mattelaer)]

Thanks a lot.

Olivier