MadAnalysis 5

definition of observable

Asked by HuanyuBi

Hi

I use mg5 to compute p p > t t~ w+ [QCD] matching to Parton Shower.

I find there is MET in ma5, and in the literature (1206.1599 Eq.(1) and 1405.3982 Eq.(1)) it is define as, |sum_{i} pt_i |, where we sumover (scalar sum) all visible particles (correct me if I am wrong)
however, I want to plot missing transverse momentum (ptmiss), which is defined as the transverse momentum of the vector summation of invisible particles, i.e.,ptmiss = pt( ve[1]+ve[2]+vmu~[1] + all possible neutrino). has this observable already been implemented in ma5?
I tried "plot pt(invisible)" and "pt( ve[1] ve[2] vmux[1])" with "define ve = 12 -12" and "define vmux = -14 14". but all of them are empty histograms. so how to define neutrinos ?
how to define ptmiss

how can I define an observable pt(l[1])+pt(l[2])+pt(l[3])+ pt(b[1])+pt(b[2])+ptmiss
i know i can define pt(l[1])+pt(l[2])+pt(l[3])+ pt(b[1])+pt(b[2]) as sPT(l[1] l[2] l[3] b[1] b[2]) (correct me if i am wrong)
but i dont know how to define ptmiss and/or i dont know how to define a particle as ve[1]+ve[2]+vmu~[1]

I want to define an observable as min( M(mu[1] b[1]), M(mu[1] b[2]) ). so how to do that ?

thanks in advance
Huanyu

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Jack Y. Araz (jackaraz) said : 		#1

Hi Huanyu

If you are looking for normal mode solution met is already defined. But defining it with respect to neutrinos is not physical simply because you can not observe neutrinos thats why MET is calculated via energy conservation using the visible particles. Also I believe you are decaying your particles right? otherwise that doesn’t make sense.

more details on normal mode can be found through reference cards: http://madanalysis.irmp.ucl.ac.be/wiki/WikiStart <http://madanalysis.irmp.ucl.ac.be/wiki/WikiStart>

If you are looking for an expert mode solution, posibilities are only limited by your C++ knowledge. I would suggest to check the public codes in our Public Analysis Database: http://madanalysis.irmp.ucl.ac.be/wiki/PublicAnalysisDatabase <http://madanalysis.irmp.ucl.ac.be/wiki/PublicAnalysisDatabase>
you can find ton of examples there alongside with corresponding documentations of the codes.

cheers

—
Jack Y. Araz

> On Jul 7, 2021, at 11:25 PM, HuanyuBi <email address hidden> wrote:
>
> [EXTERNAL EMAIL]
>
> New question #697903 on MadAnalysis 5:
> https://answers.launchpad.net/madanalysis5/+question/697903
>
> Hi
>
> I use mg5 to compute p p > t t~ w+ [QCD] matching to Parton Shower.
>
> I find there is MET in ma5, and in the literature (1206.1599 Eq.(1) and 1405.3982 Eq.(1)) it is define as, |sum_{i} pt_i |, where we sumover (scalar sum) all visible particles (correct me if I am wrong)
> however, I want to plot missing transverse momentum (ptmiss), which is defined as the transverse momentum of the vector summation of invisible particles, i.e.,ptmiss = pt( ve[1]+ve[2]+vmu~[1] + all possible neutrino). has this observable already been implemented in ma5?
> I tried "plot pt(invisible)" and "pt( ve[1] ve[2] vmux[1])" with "define ve = 12 -12" and "define vmux = -14 14". but all of them are empty histograms. so how to define neutrinos ?
> how to define ptmiss
>
> how can I define an observable pt(l[1])+pt(l[2])+pt(l[3])+ pt(b[1])+pt(b[2])+ptmiss
> i know i can define pt(l[1])+pt(l[2])+pt(l[3])+ pt(b[1])+pt(b[2]) as sPT(l[1] l[2] l[3] b[1] b[2]) (correct me if i am wrong)
> but i dont know how to define ptmiss and/or i dont know how to define a particle as ve[1]+ve[2]+vmu~[1]
>
> I want to define an observable as min( M(mu[1] b[1]), M(mu[1] b[2]) ). so how to do that ?
>
> thanks in advance
> Huanyu
>
> --
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