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

[Frank Siegert]

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.constituentsFinalState());
>> 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
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>>
>
>