MadGraph5_aMC@NLO

cross sections for a Z boson and one or more b jet

Asked by Jean

Hi
I want to calculate the production of Z boson, decaying into two leptons and produced in association with exactly one b jet and with at least two b jet?
How can generate this two processes seperetly ?

I define p = p b b~
and generate p p > z b , z > l+ l-

but I am sure it is not correct! maybe it is correct just for exactly one b jet

Best, Jean

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Olivier Mattelaer (olivier-mattelaer) said : 		#1

Hi,

I guess that you request a exact number of b-jet at parton level?
Since the shower is going to shower additional b-jet.

for exactly one b jet, I would do:
import model sm-no_b_mass
generate p p > z b , z > l+ l-
add process p p > p p > z b~, z > l+ l-

you can obviously veto the additional b jet emission from the shower if that's what you want.

For at least two b.
import model sm-no_b_mass
define BBbar =b b~
generate p p > z BBbar BBbar , z > l+ l-

and here keep the parton shower as default to have as many b as possible.

Cheers,

Olivier

PS: The inclusion of the b b~ in the proton definition is automatic with your model since 2.3.0

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Jean (jeanduvivier1992) said : 		#2

I just wanted to thank you for taking the time to reply to my problem.