How to set the value of Nf ?

Asked by Qi-wei Ke on 2018-06-27

When we calculating at LO, you can set the value of the "asrwgtflavor" parameter to set the value of Nf. But in NLO computing, there is no such parameter. How should I set it up?

Question information

Language:
English Edit question
Status:
Solved
For:
MadGraph5_aMC@NLO Edit question
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Solved by:
Olivier Mattelaer
Solved:
2018-06-27
Last query:
2018-06-27
Last reply:
2018-06-27

This question was reopened

Qi-wei Ke (ke7v) said : #1

When we calculating at LO, you can set the value of the "asrwgtflavor" parameter to set the value of Nf. But in NLO computing, there is no such parameter. How should I set it up?

Qi-wei Ke (ke7v) said : #2

When we calculating at LO, you can set the value of the "asrwgtflavor" parameter to set the value of Nf. But in NLO computing, there is no such parameter. How should I set it up?

Hi,

I would not say that such parameter is NF.
We have multiple parameter which allow to set NF for various piece of the computation.
The one that you point change the number of flavour in the running of alpha_s in the context of MLM reweighting.

At NLO, we have a single definition of NF, and all parameter are in sync. This is important to preserve NLO accuracy.
Therefore the choice of NF is done when you load the model
import model loop_sm -> nf=4
import model loop_sm-no_b_mass -> nf=5

Cheers,

Olivier

Qi-wei Ke (ke7v) said : #4

Hi,

Thank you very much for your answer. My question are resolved by your method.

Cheers,

Qi–wei Ke