[Rivet] Neutrino question - once again

David Grellscheid david.grellscheid at durham.ac.uk
Tue May 3 15:59:21 BST 2016


Hi,

thanks for your replies! I'll try to move ahead in the same way as in
the W-Finder case then, assuming that MET is the same as the sum of the
two neutrinos. Since I can assign any value for the invariant mass in
that case, I'll just assume that (iii) is a no-op, and compare
before/after on the Standard Model.

See you,

  David



On 03/05/16 15:36, Jonathan Butterworth wrote:
> Hiya
> 
> Unfortunately the fiducial definition in the paper (section 4.1) is what 
> matters, because the detector level cuts will have been "corrected" to 
> this using SM Monte Carlo.
> 
> I think this is the same as the paper, that is:
> 
> (i) two same-flavour opposite-sign electrons or muons, each with p￿T > 
> 20 GeV, |η￿| < 2.5, with ∆R(￿+, ￿−) > 0.3,
> 
> (ii) dilepton invariant mass close to the Z boson mass: 76 < m￿+￿− < 106 
> GeV,
> 
> (iii) dineutrino invariant mass close to the Z boson mass: 66 < mνν ̄ < 
> 116GeV,
> 
> (iv) no jet with pjT >25 GeV and |ηj| < 4.5,and
> 
> (v) (|pν ν ̄ − pZ |)/pZ < 0.4 and −p￿ν ν ̄ · p￿Z /pZ > 75 GeV.
> 
> I guess this is what is implemented in Rivet though I haven't checked.
> 
> (iii) is clearly problematic. I guess it was put in because it is 
> physically well-defined and better than saying "a Z", even though in 
> practice it is unmeasurable. Not good, something to highlight for future 
> measurements.
> 
> I think all the other cuts can be implmented ok just using observable 
> missing ET. I guess if we evaluate the effect of (iii) on ZZ SM MC, that 
> will tell us how important it is (that is the correction which will have 
> been applied by ATLAS). My guess is not very important...
> 
> Cheers,
> Jon
> 
> 
> On 03/05/2016 15:05, Holger Schulz wrote:
>> Hi,
>>
>>
>> I had a look into the corresponding internal document
>> (https://cds.cern.ch/record/1471026 --- section 3.3).
>>
>> There is a definition given that makes a lot more sense.
>>
>> I don't want to breach ATLAS secrecy and things so I don't know how to
>> proceed from
>> here.
>>
>> I probably could give you the names of the editors, will check.
>>
>>
>> Holger
>>
>> On 03/05/16 14:31, David Grellscheid wrote:
>>> Hi all,
>>>
>>> what's our justification again for being allowed to use two
>>> distinguishable truth neutrinos in ATLAS_2012_I1203852 ==
>>> http://arxiv.org/pdf/1211.6096.pdf ?
>>>
>>> I'll need to rewrite that section along the lines of the W-Finder
>>> fixes, to assume generic invisibles rather than standard model
>>> neutrinos. Can someone on ATLAS please help me to interpret this
>>> statement from the paper in terms of measurables?
>>>
>>>   "dineutrino invariant mass close to the Z boson mass"
>>>
>>> The event selection section is very brief on how I get to the Z-nunu
>>> candidate in the first place.
>>>
>>> Thanks,
>>>
>>>   David
>>> _______________________________________________
>>> Rivet mailing list
>>> Rivet at projects.hepforge.org
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>>
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> 


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