How to set up the mass of c quark and its decay width?
In the param_card.dat of default model before the values of some masses and decay widths (for example, those of c quark) is written:
## Dependent parameters, given by model restrictions.
## Those values should be edited following the
## analytical expression. MG5 ignores those values
## but they are important for interfacing the output of MG5
## to external program such as Pythia.
It seems that it means that by changing the mass and the decay width of the c quark in param_card I will not really change them for MadGraph simulations. I have few questions.
1) Could you please tell me what is the proper way for changing the values of c mass and decay width? Is there a simple way to do this (say, downloading some specific model, changing some values in a piece of code and so on)?
2) I am interested in the process
p p > c c~, c > e+ ve s
and it seems to me that in this process I can "imitate" the c quark by the top quark with changed mass and decay width in param_card. The process which imitates (1) is
p p > t t~, t > e+ ve b,
where b mass is also set to zero. Is it meaningful? If yes, then is it possible?
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