block hidden & block mass

Hi,

Since I'm not an author of the model that you are using. (do not know which one you are using actualy)
It would not be possible to comment on "why the model is implemented like that"

I can only describe the param_card as written in your email.

According to the card, the mass of the particle with pdg 1023 (the zp particle)
is not a free parameter of the model.
MG5aMC will therefore not read that information.

According to the card, the parameter is given by an analytical expression which forces him to be equal to the
mZDinput input parameter defined as part of the hidden block.
As said above, do not ask me why the model author decides to do it in that way.

Therefore when you ask,
> set mZDinput 12.0
we change in the param_card the parameter named "mZDinput" which is part of the block hidden.
Now if you run the command
"update dependent"
after the set command, you will see that MG5aMC computes all the formula for the mass/width which are not free parameters and replaced them by their value (and therefore you should see that the mass of zp is also put to 12 GeV)

Note that we automatically try to run "update dependent" when you are done with the edition of the card.
(But with some timer to avoid to run it with the model is quite complex). As said above, it is actually not important for MG5aMC since we will never use the value written in the block mass. But it can be important for other code to have the correct mass written in the mass block (like Pythia,...)

Cheers,

Olivier

> On 2 Sep 2018, at 19:52, audiya fatihah <email address hidden> wrote:
>
> New question #673284 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/673284
>
> hi sorry, im very new to mg5
>
> im trying to change the mass of mZDinput
>
> but when i
>> set mZDinput 12.0
>
> only the block hidden changes,
> what is the difference between the block hidden and block mass, for my case should i change both or is this command doing what i want it to do (which is change the mZD)
>
> ##################################
> ## INFORMATION FOR HIDDEN
> ###################################
> Block hidden
> 1 1.200000e+01 # mZDinput
> 2 2.000000e+02 # MHSinput
> 3 1.000000e-02 # epsilon
> 4 1.000000e-09 # kap
> 5 1.279000e+02 # aXM1
>
> ###################################
> ## INFORMATION FOR MASS
> ###################################
> Block mass
> 4 1.420000e+00 # MC
> 5 4.700000e+00 # MB
> 6 1.743000e+02 # MT
> 11 5.110000e-04 # ME
> 13 1.057000e-01 # MM
> 15 1.777000e+00 # MTA
> ## 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.
> 1 0.000000 # d : 0.0
> 2 0.000000 # u : 0.0
> 3 0.000000 # s : 0.0
> 12 0.000000 # ve : 0.0
> 14 0.000000 # vm : 0.0
> 16 0.000000 # vt : 0.0
> 21 0.000000 # g : 0.0
> 22 0.000000 # a : 0.0
> 23 91.188000 # z : mZinput
> 24 80.275296 # w+ : cw*MZ0
> 25 125.000000 # h : MHinput
> 35 200.000000 # h2 : MHSinput
> 1023 20.000000 # zp : mZDinput
>
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Thanks Olivier Mattelaer, that solved my question.

sorry, 1 more to be clear of, what does it mean by block hidden, is this a syntax for the model?

Hi,

The name of the block does not have any meaning in itself,
I guess that the model author have called it like this since it is related to some sort of hidden sector.

Cheers,

Olivier