[Rivet] missingEt variable in WFinder constructor

[Andy Buckley]

Hi Ines,

This must be a meaning of "simpler version" that I'm not familiar with!
I've attached a real minimal working example ;-) The version you
provided did not compile with the latest version of Rivet, so I guess
you are using an old one: which version?

Anyway, with my cut-down analysis I can reproduce the problem. I added a
printout line to WFinder.cc and see that the value that we are using as
an ET cut is much larger than the neutrino pT:

Rivet.Projection.WFinder: DEBUG  W- reconstructed from:
   (599.426; 30.861, -0.00629191, 598.631) 13
 + (114.54; -28.4288, 0.264693, 110.956) -14
Rivet.Projection.WFinder: DEBUG  Scalar ET = 131.66 GeV vs. required =
20 GeV
Rivet.Analysis.MinimalAnalysis: INFO  pT_nu1 = 28.43 GeV

This looks like a projection bug to me -- I need to look into the
definition of the MissingMomentum projection that we're using, but
surely missing ET needs to be a vector rather than scalar quantity. This
is even suggested in the code comments:

    /// @todo Restrict missing momentum eta range? Use vectorET()?

Frank, should I change this:

    if (vismom.scalarEt() < _etMiss) {

to use vectorEt instead?

Andy


On 02/02/15 12:30, Inês Ochoa wrote:
> Hi Andy,
> 
> I attached a simpler version of the routine I'm using. I run it with
> Rivet 2.1.1 and I see that:
> 1. the nuPt variable I print out has no cut on it
> 2. changing the value of the MET argument does not change the number of
> events with reconstructed W's above a given pT
> 
> Thanks!
> Inês
> 
> On 02/02/15 12:02, Andy Buckley wrote:
>> Hi again Ines,
>>
>> Can you send your example analysis code so we can easily re-run & check?
>> Which version of Rivet are you using? I should check that some of the
>> recent interface changes did not accidentally break a MET cut, but this
>> will be far easier with an example code that I can just run out of the
>> box in the latest Rivet.
>>
>> Cheers,
>> Andy
>>
>>
>> On 27/01/15 11:06, Inês Ochoa wrote:
>>> Hi Frank,
>>>
>>> The WFinder is defined as:
>>>
>>> WFinder wfinder(-6.0, 6.0, 20.0*GeV, PID::MUON, 0.0*GeV, 1000.0*GeV,
>>> 20.0*GeV, 0.1);
>>>
>>> I can see that the documentation on WFinder now has some modifications
>>> on the list of arguments, but this is consistent with previous
>>> versions... I've also checked that the constituentLeptons()[0] pT does
>>> have a cut at 20 GeV.
>>>
>>> Cheers,
>>> Inês
>>>
>>> On 27/01/15 10:56, Frank Siegert wrote:
>>>> Hi Inês,
>>>>
>>>> The missingET argument should apply a pT cut to the (in)visible
>>>> momentum in your inputfs (which should include the neutrino). So your
>>>> observation would definitely not be expected, and I don't currently
>>>> see a reason why this would go wrong. Could you post a code snippet of
>>>> how your WFinder is defined in your analysis, or attach the full
>>>> analysis code?
>>>>
>>>> Cheers,
>>>> Frank
>>>>
>>>>
>>>>
>>>>
>>>> On 27 January 2015 at 11:44, Inês Ochoa <Ines.Ochoa at cern.ch> wrote:
>>>>> Dear Rivet developers,
>>>>>
>>>>> I am using Rivet 2.1.1 and selecting a W candidate with WFinder. I am
>>>>> applying a cut on the missing Et (as one of the arguments of
>>>>> WFinder()) but
>>>>> when accessing the neutrino with constituentNeutrinos()[0] I see that
>>>>> there
>>>>> is no cut on its Pt. In fact, changing the MET cut on the WFinder
>>>>> constructor seems to have no impact on the resulting number of events.
>>>>>
>>>>> Is this a known problem? Should that argument be ignored and the cut
>>>>> applied
>>>>> on the constituentNeutrino object instead?
>>>>>
>>>>> Thanks!
>>>>> Inês
>>>>> _______________________________________________
>>>>> Rivet mailing list
>>>>> Rivet at projects.hepforge.org
>>>>> https://www.hepforge.org/lists/listinfo/rivet
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>>> Rivet mailing list
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>>
>>


-- 
Dr Andy Buckley, Royal Society University Research Fellow
Particle Physics Expt Group, University of Glasgow / PH Dept, CERN
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