[Rivet] VisibleFinalState -- black or white list [Was: r3383]

[Andy Buckley]

On 04/10/11 19:01, David Grellscheid wrote:
>
> Sorry, forgot list reply.
>
>
>
> Hi Frank,
>
>> Ok, fine with me, as long as we make an effort to think about all
>> special cases. A few come to my mind right now:
>>
>> 1. What about gluinos (as far as my limited SUSY knowledge goes, I
>> think in some scenarios they can be LSP's)?
>
> As hadrons they should be covered.

Are gluinos hadrons? They are still coloured (until bound into an 
R-hadron) so I'd have thought a gluino is still a parton, just a weird 
one. Functionally, it comes down to whatever the Rivet PID::isHadron 
function stolen from HepPID says about the gluino PDG code.

Re. gluino as LSP, *my* limited SUSY knowledge/prejudice is that due to 
the strong coupling they normally RGE-evolve to be among the *heaviest* 
sparticles. But I'll readily believe that anything's possible in one 
corner of SUSY space or other ;)

>> 2. Could beam remnants contain anything strange uncharged at parton
>> level? 3. Should we allow e.g. stable Z as final states and treat the
>> Z as visible?
>
> To me using parton-level analyses is using Rivet outside of its main
> purpose. It's the same for SUSY analyses I guess. So how about making
> projections for a certain context? VisiblePartonProjection etc?

Parton-level analysis is a feature creep on what Rivet was designed for, 
for sure, but I think there is some value in trying to make a lot of 
standard analyses work without modification at parton level. Jet 
analyses are the obvious one: as long as the partons are marked stable, 
the jet alg will cluster them and then the analysis continues as normal. 
Enabling that seems like a very good idea to me since there are 
legitimate reasons to want to see the effects of shower, hadronisation, 
MPI, etc. on those distributions.

Stable Zs are a bit of a different situation to my mind... although I 
guess we could adapt the ZFinder implementation to "return the Z with 
status = 1 if found, otherwise reconstruct". I think I'd want to be 
given a fairly compelling use case before we start further complicating 
projections that are already quite complex, though!

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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