[Rivet] W finder and PartonJet question

[Stefano Camarda]

Hi Kristin,
what I would do, is to switch off MPI and hadronization, (and QED FSR) 
in pythia.
With QED shower off, whatever the lepton definition, we get born level 
leptons.
With hadronization and MPI off, we get parton level jets.
Then exactly the same rivet routine can be used to evaluate the corrections.
In Herwig++ there should be similar switches.
Cheers,
Stefano

On 05/15/2014 11:30 AM, kristin Lohwasser wrote:
> Dear all,
>
> I have a (couple of) question(s) concerning the WFinder implementation 
> in Rivet and how to get Parton Jets in Rivet (is this possible at all?).
>
> Essentially I want to get BORN level electrons, for this I am using 
> the WFinder (since as I understand, this is the recommended way to 
> reconstruct W's in Rivet -- please correct me, if I am wrong)
>
> 1) CLUSTERING DEFINITION
> --> For Born level I am not sure, what setting for the Photon 
> clustering to use, essentially for the below settings, the 
> WFinder::NOCLUSTER and WFinder::CLUSTERNODECAY yield the same results 
> (but these are different from my cross check numbers for Born level)
>       WFinder wfinder_born_el(fs, -2.5, 2.5, 20*GeV, PID::ELECTRON, 
> 0*GeV, 8000*GeV, 25*GeV, 0.2, WFinder::NOCLUSTER );
> so I am not sure, whether any of the ENUMS will actually selec W-Born 
> level.
>
> 2) Difference for MET
> I understand, you set the MET cut in the WFinder Declaration (25*GeV 
> in the above case).
> However, I apply a MT cut afterwards as well and there I also doublely 
> applied the MET cut -- however when I *REMOVED* it, the number of 
> selected events *CHANGED*, which should not happen (code follows now):
>
>
>       if (!wfinder_born_mu.particles().empty()) {
>         const FourMomentum& nu = 
> wfinder_born_el.constituentNeutrinos()[0].momentum();
>         if ( calcMT(nu, 
> wfinder_born_el.constituentLeptons()[0].momentum())  > 40*GeV && 
> nu.pT()>25*GeV) {
>           keepevent=true;
> }}
>
>       if (!keepevent) {
>         MSG_DEBUG("event does not pass mT and MET cuts");
>         vetoEvent;
>       }
> COUNT_PASS_W++;
>
> 3) How can want one get Parton Jets in Rivet? I tried to find some 
> other analysis using this, e.g. ATLAS jets, but it seems, they are not 
> implemented. It would be great, if you could suggest me something.
>
> Thanks & Best
> Kristin
>
>
>
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