[Rivet] Rivet ZFinder and taus

[Andy Buckley]

On 03/02/12 10:42, Lynn Marx wrote:
> Hi Andy,
>
> I have a question about the ZFinder and taus. It is a fairly naive
> question and I realize I should have played around with Rivet a bit
> more before emailing you but analysis things are a little hectic at
> the moment so I hope it is ok if I bother you anyway.

Hi Lynn,

I'll answer it this time but would appreciate if you can send queries to 
the rivet at projects.hepforge.org email list in future -- I don't have 
enough time to personally answer all the questions!

> I need to validate some samples that have either W's or Z's (or both)
> decaying to taus. When I naively used my code I already had set up
> for muons and electrons and changed in the ZFinder(..."MUON"...) to
> ZFinder(..."TAU"...) it did not like it presumably because the
> ZFinder uses FinalState, in which there will probably then not be any
> taus. Is there an easy work around to this? Maybe use
> UnstableFinalState projection instead?

Yes, unfortunately we don't have tau (or "proper" hadronic) 
reconstruction of Ws or Zs at the moment. UnstableFinalState is the best 
way to find taus, and then you can do the tau+nu or tau+tau addition to 
get the W/Z 4-vector as usual. The W and Z finders dedicate some 
significant effort to (optionally) including photons in a cone around 
the mu or e into the W/Z definition: I'm not sure if that's an effect 
that is important for taus, but worth thinking about.

Good luck!
Andy

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

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