[Rivet] undocumented behaviour in wfinder/zfinder (bug ?)

[Nicolas Morange]

Ok, that's exactly the diff of the last commit by Frank :-D
123	 	//    /// Apply the RFS here so that it can be acquired later via the 
remainingFinalState method 
124	 	//    applyProjection<FinalState>(e, "RFS");

So please diregard my question...

Cheers,
Nicolas

Le Mardi 2 Août 2011 19:06:40 Andy Buckley a écrit :
> Hi Nicholas,
> 
> As far as I can tell, line 124 in both ZFinder.cc and ZFinder.hh are
> empty! Can you point explicitly at a line on
> http://projects.hepforge.org/rivet/trac/browser/trunk/src/Projections/ZFinde
> r.cc ? Thanks :)
> 
> Andy
> 
> On 02/08/11 18:34, Nicolas Morange wrote:
> > Hello Frank,
> > 
> > I've read the new code, and it seems correct to me. Thanks !
> > Maybe one little thing (I don't understand fully how projections work):
> > is it normal that line 124 of ZFinder.cc is commented ?
> > 
> > I was able to discover this bug because I'm studying Z+b, where the
> > other
> > leptons in the event play a much more important role than in Z+jets,
> > because of the semi-leptonic decays. The overall effect was ~3% on the
> > inclusive cross-section.
> > 
> > Cheers,
> > Nicolas
> > 
> > Le Mardi 2 Août 2011 12:12:06 Frank Siegert a écrit :
> >> Hi Nicolas,
> >> 
> >> I have revamped the implementation of [WZ]Finder to correctly exclude
> >> 
> >> particles from the RemainingFinalState:
> >>     http://projects.hepforge.org/rivet/trac/changeset/3268
> >> 
> >> IMO it's much easier to read now, so maybe you could take another look
> >> and check whether you see any remaining inconsistency. You can browse
> >> that revision at
> >> 
> >>     http://projects.hepforge.org/rivet/trac/browser/trunk?rev=3268
> >> 
> >> The idea now is that the WFinder and ZFinder are FinalState
> >> projections
> >> which have the original constituents as _theParticles and the W or Z
> >> as
> >> _bosons. This makes it easier to exclude the original particles from
> >> the
> >> remaining final state while still allowing for re-using the existing
> >> projections (one of which, LeptonClusters, is also much simpler now).
> >> 
> >> These changes don't seem to have a large effect, but they do have an
> >> effect (very small) of increasing jet multiplicity, as would be
> >> expected
> >> since we include more particles in the jets now:
> >> 
> >> http://fsiegert.web.cern.ch/fsiegert/tmp/wzfinder
> >> 
> >> This will be released very soon as Rivet 1.6.0.
> >> 
> >> Best,
> >> Frank
> >> 
> >> On 29/07/11 19:54, Nicolas Morange wrote:
> >>> Hi Frank,
> >>> 
> >>> Thanks for your quick answer.
> >>> For what I see all the other leptons are removed, for
> >>> LeptonClustersConstituents (which contains the particles that will
> >>> eventually be removed) doesn't know about pT and eta cuts. That
> >>> seems
> >>> normal, as only the clustered leptons have to pass the cuts.
> >>> 
> >>> As a quick&dirty workaround I'm trying to merge :
> >>> zfinder.remainingFinalState()
> >>> + zfinder.getProjection<FinalState>("LeptonClusters")
> >>> - zfinder.constituentsFinalState()
> >>> which adds the composite clustered leptons to the final state.
> >>> that's not completely correct but that should do a decent job.
> >>> 
> >>> Cheers,
> >>> Nicolas
> >>> 
> >>> Le Vendredi 29 Juillet 2011 19:30:41 Frank Siegert a écrit :
> >>>> Hi Nicolas,
> >>>> 
> >>>> I'm afraid you are right, there is an inconsistency. It is not
> >>>> removing
> >>>> all leptons though, but "only" the ones which pass the initial
> >>>> lepton
> >>>> cuts. But that's still more than the ones used as Z, and thus
> >>>> wrong.
> >>>> 
> >>>> It's not obvious to me how to solve this with the current approach
> >>>> of
> >>>> chaining existing projections (LeptonClusters and
> >>>> InvMassFinalState in
> >>>> this case). I would need to be able to access the original
> >>>> particles
> >>>> which form the two LeptonClusters accepted by IMFS. So there
> >>>> doesn't
> >>>> seem to be a way around duplicating LC and IMFS into a combined
> >>>> projection, which might as well be the ZFinder then.
> >>>> 
> >>>> I'll think about this for an hour and if I (or anybody else on
> >>>> this
> >>>> list) haven't come up with a better solution by then, I'll start
> >>>> working
> >>>> on it.
> >>>> 
> >>>> Cheers,
> >>>> Frank
> >>>> 
> >>>> On 29/07/11 16:46, Andy Buckley wrote:
> >>>>> Hi Nicholas,
> >>>>> 
> >>>>> I'm a bit uncertain about exactly how the remainingFS works for
> >>>>> WFinder
> >>>>> and ZFinder... hopefully someone can clarify and check that
> >>>>> there is
> >>>>> no
> >>>>> bug: Frank S, can you help?
> >>>>> 
> >>>>> We're just about to make a new Rivet release, and I just
> >>>>> uploaded
> >>>>> the
> >>>>> release tarballs to the HepForge downloads area... but I'll wait
> >>>>> for
> >>>>> confirmation that there's not a bug before making the release
> >>>>> official.
> >>>>> 
> >>>>> Cheers,
> >>>>> Andy
> >>>>> 
> >>>>> On 29/07/11 15:29, Nicolas Morange wrote:
> >>>>>> Hello,
> >>>>>> 
> >>>>>> I'm writing a Z+jets analysis.
> >>>>>> Thus I use a ZFinder whose remainingFinalState() is chained to
> >>>>>> a
> >>>>>> FastJet. However, the code in ZFinder
> >>>>>> 
> >>>>>> 00044 LeptonClusters leptons(fs, bareleptons, dRmax,
> >>>>>> 00045 clusterPhotons, excludePhotonsFromRFS,
> >>>>>> 00046 etaRanges, pTmin);
> >>>>>> 00047 addProjection(leptons, "LeptonClusters");
> >>>>>> 00048 InvMassFinalState imfs(leptons, std::make_pair(pid,
> >>>>>> -pid),
> >>>>>> m2_min,
> >>>>>> m2_max);
> >>>>>> 00049 addProjection(imfs, "IMFS");
> >>>>>> 00050
> >>>>>> 00051 VetoedFinalState remainingFS;
> >>>>>> 00052
> >>>>>> remainingFS.addVetoOnThisFinalState(leptons.constituentsFinalS
> >>>>>> tate
> >>>>>> ());
> >>>>>> 00053 addProjection(remainingFS, "RFS");
> >>>>>> 
> >>>>>> gives me the impression that not only the Z leptons are
> >>>>>> removed
> >>>>>> from
> >>>>>> the
> >>>>>> remainingFS, but also the other leptons in the event.
> >>>>>> Is this correct ?
> >>>>>> And how should I do to remove only the Z leptons (and
> >>>>>> associated
> >>>>>> photons) from
> >>>>>> the final state ?
> >>>>>> 
> >>>>>> Cheers,
> >>>>>> Nicolas
> >>>>>> _______________________________________________
> >>>>>> Rivet mailing list
> >>>>>> Rivet at projects.hepforge.org
> >>>>>> http://www.hepforge.org/lists/listinfo/rivet
> > 
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