[Rivet] ZFinder problem report

[Andy Buckley]

Hi Elena,

Can you clarify what you expected the Rivet photon clustering arguments 
to do and what you are actually seeing?

Cheers,
Andy


On 06/09/11 11:26, Andy Buckley wrote:
> On 30/08/11 19:19, Yatsenko, Elena wrote:
>> Hello,
>>
>> During implementation of the ATLAS ZpT analysis with Rivet v1.6.0
>> we've found a problem in ZFinder class with clusterPhotons flag.
>> If clusterPhotons =«false» dR cut is not effective for the 4 momentum
>> of the Z boson .
>> So in our case
>>
>> ZFinder zfinder_dressed_el(-2.4, 2.4, 20, ELECTRON, 66.0*GeV,
>> 116.0*GeV, 0.1, false, false);
>> and
>> ZFinder zfinder_bare_el(-2.4, 2.4, 20, ELECTRON, 66.0*GeV, 116.0*GeV,
>> 0.0, false, false);
>>
>> will give the same results. While the class documentation suggest that
>> clusterPhotons is meant to only correct the 4 vectors of the decay
>> lepton.
>
> Hi again Elena,
>
> I think that the main issue here is that the class documentation needs
> to be improved on W/ZFinder and LeptonClusters to explain exactly what
> these bool flags imply. It's been redeveloped a bit recently and *I'm*
> not entirely sure what Frank intended!
>
> What do *you* expect these flags to do? My understanding is that if you
> set clusterPhotons=false then the Z mass will be constructed without
> using dR: I'm not sure why we have a separate flag for that, but
> presumably there has been a use case for it. I think that the
> trackPhotons flag is used to decide whether or not the photons are
> attached to the returned leptons, from my reading of the docstring, but
> Frank should clarify that: it is a bit confusing.
>
> Cheers,
> Andy
>


-- 
Dr Andy Buckley
SUPA Advanced Research Fellow
Particle Physics Experiment Group, University of Edinburgh

The University of Edinburgh is a charitable body, registered in
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