[Rivet] Question about WFinder

[Piergiulio Lenzi]

Hi Andy,
    I think that in the current implementation you are forced to have 
the same eta cut for both the neutrino and the lepton,
which experimentally would mean that you calculate MET in the same eta 
range that you use for the tracking.
I think one could either allow for the possibility of putting different 
pt/eta cuts for the charged lepton and the neutrino, or put no cut on 
the neutrino and then use the TotalVisibleMomentum with proper cuts in 
eta to reproduce what in an experiment is used do calculate MET.
I have never studied MET experimentally however, so probably one should 
look carefully at what they did at Tevatron for the W analysis to find 
what is the best solution.
Cheers,
Giulio

Andy Buckley wrote:
> Hi Giulio,
>
> This is a good idea. I'm putting together something similar to this, and
> will add the multiple eta ranges to the identified and charged final
> state projections. Just to check, I think it makes sense to have no eta
> cuts on the neutrino either: right?
>
> Andy
>
>
> On 25/02/10 17:15, Piergiulio Lenzi wrote:
>   
>> Hi Andy,
>>    thanks for your answer,
>> I actually found a trick to do the job (well something still has to be
>> refined).
>> The idea is to run the InvMassFinalState on a MergedFinalState produced
>> out of two IdentifiedFinalState's, one with all the charged leptons,
>> with pt and eta cuts, and one with all the neutrinos.
>> The only problem is that IdentifiedFinalState doesn't take a vector of
>> eta ranges, but I think this is easily fixable.
>> I'm attaching a patch file that I produced on top of 1.2.0b. I hope this
>> is a good starting point .
>> Thanks!
>> Giulio
>>
>>
>>
>> Andy Buckley wrote:
>>     
>>> On 24/02/10 17:37, Piergiulio Lenzi wrote:
>>>  
>>>       
>>>> Dear Rivet developers,
>>>>     I'm trying to use the WFinder projection, and I noticed that the
>>>> pt cut and eta  range are actually applied both to the charged lepton
>>>> and the neutrino. Can you confirm this?
>>>> I'm not sure whether this is the expected behavior or not, especially
>>>> the eta cut on the neutrino is not something that one can apply in an
>>>> experiment. If I had to choose, I would prefer not to check the
>>>> neutrino eta and pt at all when building the W candidate, and then
>>>> reproduce the experiment MET cut with a cut on TotalVisibleMomentum.
>>>> What do you think about that?
>>>>     
>>>>         
>>> Hi Giulio,
>>>
>>> I completely agree. I wrote the WFinder as a partial clone of the
>>> ZFinder, really only modified to make sure that photons aren't clustered
>>> in a cone around the neutrino. It would make sense to also take this
>>> more realistic approach to MET and lepton pT cuts for W reconstruction.
>>>
>>> I was hoping that I could make this fix quickly, but the
>>> InvMassFinalState projection takes a single FinalState projection as a
>>> constructor argument so it's not immediately easy to make the change.
>>> I'll see if I can neatly enhance the InvMassFinalState to be able to be
>>> directly supplied with particles, which seems the easiest approach: I'm
>>> not immediately sure if this will screw up the caching system. Any other
>>> ideas, e.g. from Frank?
>>>
>>> Andy
>>>
>>>   
>>>       
>
>
>