Electron and muon behave differently in polarized VBS SSWW process

Asked by xiao jie on 2020-02-13

Dear MG experts,

I am running process:

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

I drew electron pt and muon pt distributions for events that in emu final state, you can find the plot here:
http://jixiao.web.cern.ch/jixiao/polar/m_ptl1_wmwm_tl.pdf

meanwhile, I also consider following process:

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

for this process, the pt distribution for emu final state is here:
http://jixiao.web.cern.ch/jixiao/polar/m_ptl1_wmwm_lt.pdf

Do you know what caused those discrepancies?

Best regards,
Jie

Question information

Language:
English Edit question
Status:
Solved
For:
MadGraph5_aMC@NLO Edit question
Assignee:
No assignee Edit question
Solved by:
Olivier Mattelaer
Solved:
2020-02-13
Last query:
2020-02-13
Last reply:
2020-02-13

Hi,

We have some symmetry handling for decay of identical particle.

In this case your process is interpreted like this:
> generate p p > w-{0} w-{T} j j QED=4 QCD=0, w- > e- vl~ , w- > mu- vl~
and it therefore assumes that the longitudinal decays into lepton and that the transverse decay into muons.

We are looking into those issues right now and this will be fixed in the next version of the code (2.7.1).
(I did not think about that special case and none of us/beta tester did)

Cheers,

Olivier

> On 13 Feb 2020, at 20:22, xiao jie <email address hidden> wrote:
>
> New question #688752 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/688752
>
> Dear MG experts,
>
> I am running process:
>
> define l+ = e+ mu+
> define l- = e- mu-
> define vl = ve vm
> define vl~ = ve~ vm~
> generate p p > w-{0} w-{T} j j QED=4 QCD=0, w- > l- vl~
>
> I drew electron pt and muon pt distributions for events that in emu final state, you can find the plot here:
> http://jixiao.web.cern.ch/jixiao/polar/m_ptl1_wmwm_tl.pdf
>
> meanwhile, I also consider following process:
>
> define l+ = e+ mu+
> define l- = e- mu-
> define vl = ve vm
> define vl~ = ve~ vm~
> generate p p > w-{T} w-{0} j j QED=4 QCD=0, w- > l- vl~
>
> for this process, the pt distribution for emu final state is here:
> http://jixiao.web.cern.ch/jixiao/polar/m_ptl1_wmwm_lt.pdf
>
> Do you know what caused those discrepancies?
>
> Best regards,
> Jie
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

xiao jie (talalal) said : #2

Thanks Olivier Mattelaer, that solved my question.