[Rivet] Neutrino question - once again

[Jonathan Butterworth]

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
>> _______________________________________________
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>> Rivet at projects.hepforge.org
>> https://www.hepforge.org/lists/listinfo/rivet
>
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-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Prof. Jonathan Butterworth,              http://www.hep.ucl.ac.uk/~jmb/
Head, Physics and Astronomy Department            Tel: +44 20 7679 3444
University College London                 Gower St, London WC1E 6BT, UK
ATLAS, CERN                                       Tel: +41 22 76  72340
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