MadGraph5_aMC@NLO

How to set the value of Nf ?

Asked by Qi-wei Ke

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?

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Olivier Mattelaer
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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?

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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?

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Best Olivier Mattelaer (olivier-mattelaer) said : 		#3

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

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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