MadGraph5_aMC@NLO

how to define mu- decayed from longitudianal w boson in same-sign WW process

Asked by xiao jie

Dear authors,

I am using Madgraph5 v2.7.0 to simulate the emu final state in VBS same-sign WW process.

I want to have a sample that only mu- is decayed from longitudianal polarized w boson using following syntax:
generate p p > w-{0} w-{T} j j QED=4 QCD=0, w-{0} > mu- vm~, w-{T} > e- ve~

when I type 'output vbs_wmwm_lt', following error occurs:

Command "output vbs_wmwm_lt" interrupted with error:
InvalidCmd : In decay-chain polarization can only be specified in production not in decay. Please Retry

I want to know is it possible to use new syntax in https://answers.launchpad.net/mg5amcnlo/+faq/2243 to simulate mu- is decayed from longitudianal W, e- is decayed from transverse W.

Best regards,
Jie

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Olivier Mattelaer
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Best Olivier Mattelaer (olivier-mattelaer) said : 		#1

Hi,

Looks like we did not think about/validate the case of identical particles with different polarization.

In 2.7.0, you can however simply do:

> generate p p > w-{0} w-{T} j j QED=4 QCD=0, w- > mu- vm~, w- > e- ve~

and this will do the trick.
I'm not however 100% sure that all symmetry factor are correctly handle.

For 2.7.1, the symmetry factor will be fixed for such cases and this is too early to say if the above trick will work or not.

Cheers,

Olivier

> On 4 Feb 2020, at 15:52, xiao jie <email address hidden> wrote:
>
> generate p p > w-{0} w-{T} j j QED=4 QCD=0, w-{0} > mu- vm~, w-{T} > e- ve~

Revision history for this message
xiao jie (talalal) said : 		#2

Thanks Olivier Mattelaer, that solved my question.