[Rivet] Question concering PromptFinalState projection

[Andy Buckley]

It's a general disclaimer that any treatment of unstable hadrons or 
requirement of promptness in Rivet will not work with FHerwig without 
status rewriting (which *should* have been switched on in the ATLAS 
samples).

I wouldn't add warnings specifically to any analysis codes, because it's 
a general problem with FHerwig+Rivet.

Andy


On 26/01/17 12:51, Dominic Hirschbuehl wrote:
> Hi Andy, Chris,
>
> I completely agree, that we should not use the fortran generators
> anymore, however they are still default generators for a lot of 8 TeV
> analyses ....
>
> So maybe one should put somewhere a disclaimer, that at least our top
> routines cannot be used with fortran herwig.
>
> Cheers
>   Dominic
>
> On Thu, Jan 26, 2017 at 10:59:52AM +0000, Andy Buckley wrote:
>> Exactly. I think we may be now more than 10 years past the point
>> that it was declared superseded and unsupported ;-)
>>
>> Andy
>>
>>
>> On 25/01/17 19:10, Christian Gutschow wrote:
>>> Hi,
>>>
>>> the Rivet routines work perfectly fine with the Herwig shower (!) — it’s
>>> just Fortran Herwig that doesn’t comply with the HepMC standard, for
>>> which the routines might not work. All the more reason to move to the
>>> modern incarnations of Herwig...
>>>
>>> Cheers,
>>> Chris
>>>
>>>> On 25 Jan 2017, at 17:31, Dominic Hirschbuehl <dhirsch at mail.cern.ch
>>>> <mailto:dhirsch at mail.cern.ch>> wrote:
>>>>
>>>> Hi Andy,
>>>>
>>>> thanks a lot for the quick answer.
>>>> It is indeed Fortran Herwig and I ran over a MC12 sample. Maybe the
>>>> rewriter was not used for this sample.
>>>>
>>>> However, does this mean, that we need to put some disclaimer to our
>>>> Rivet routines, that they don't work for the Herwig shower, since
>>>> everybody outside ATLAS won't have the rewriter, right?
>>>>
>>>> Cheers
>>>> Dominic
>>>>
>>>> On Wed, Jan 25, 2017 at 05:24:21PM +0000, Andy Buckley wrote:
>>>>> Hi Dominic,
>>>>>
>>>>> Is this *Fortran* Herwig?
>>>>>
>>>>> Indeed it uses non-standard status codes, so Rivet's algorithms will
>>>>> break. But in ATLAS we added a Herwig status rewriter, to make it
>>>>> compliant -- is that not being used in your sample?
>>>>>
>>>>> The restriction to look at status 2 only (because status 1 can't be
>>>>> an ancestor) is maybe a bit extreme: we could also allow status
>>>>> codes > 10 to be used (the MC range if I remember correctly). But
>>>>> then we wouldn't know what sort of generator-dependence we'd be
>>>>> introducing: for example Herwig++ uses status 11 for everything that
>>>>> isn't 1, 2, or 4 so we could end up walking up precisely the sort of
>>>>> unphysical debug trees that the code is trying to avoid...
>>>>>
>>>>> Short answer: the generator needs to be compliant with the HepMC
>>>>> status scheme. But I thought we had already modified FHerwig in that
>>>>> way.
>>>>>
>>>>> Andy
>>>>>
>>>>>
>>>>> On 25/01/17 16:55, Dominic Hirschbuehl wrote:
>>>>>> Dear all,
>>>>>>
>>>>>> I have a question concerning the PromptFinalState projection.
>>>>>> I did a study on acceptences of lep+jets ttbar events, where I found an
>>>>>> unexpected differences between Powheg+Pythia6 and Powheg+Herwig samples.
>>>>>> The differences occured already on the level of the lepton acceptance,
>>>>>> which includes a dilepton veto.
>>>>>>
>>>>>> After some investigation I have the suspicion, that leptons from hadron
>>>>>> decays are counted as prompt leptons.
>>>>>>
>>>>>> Looking to the actual implementation of isPrompt I found this line
>>>>>> of code:
>>>>>> if (ancestor->status() != 2) continue; // no non-standard statuses or
>>>>>> beams to be used in decision making
>>>>>>
>>>>>> Is there a reason to restrict the status codes to 2?
>>>>>> If I print out all ancestors of a "prompt lepton" from a Herwig
>>>>>> showered event
>>>>>> I get:
>>>>>>
>>>>>>  pdg = 2212 status = 101 0 1
>>>>>>  pdg = 2212 status = 102 0 1
>>>>>>  pdg = 21 status = 121 1 0
>>>>>>  pdg = 21 status = 122 1 0
>>>>>>  pdg = 6 status = 123 1 0
>>>>>>  pdg = 6 status = 143 1 0
>>>>>>  pdg = 6 status = 3 1 0
>>>>>>  pdg = 6 status = 155 1 0
>>>>>>  pdg = 24 status = 123 0 0
>>>>>>  pdg = 24 status = 3 0 0
>>>>>>  pdg = 24 status = 155 0 0
>>>>>>  pdg = 4 status = 124 1 0
>>>>>>  pdg = 4 status = 144 1 0
>>>>>>  pdg = 4 status = 2 1 0
>>>>>>  pdg = 21 status = 2 1 0
>>>>>>  pdg = 4 status = 158 1 0
>>>>>>  pdg = -2 status = 158 1 0
>>>>>>  pdg = 91 status = 183 0 0
>>>>>>  pdg = 411 status = 197 0 1
>>>>>>
>>>>>> which would indicate that the identified lepton actually comes fomr a
>>>>>> hadron.
>>>>>>
>>>>>> Do I miss something?
>>>>>>
>>>>>> Thanks in advance
>>>>>> Dominic
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> _______________________________________________
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>>>>>> https://www.hepforge.org/lists/listinfo/rivet
>>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Dr Andy Buckley, Lecturer / Royal Society University Research Fellow
>>>>> Particle Physics Expt Group, University of Glasgow
>>>>
>>>> --
>>>> /---------------------------------------------------------------------\
>>>> |                     Dr. Dominic Hirschbuehl                           |
>>>> \   Bergische Universitaet Wuppertal - Exp. Elementarteilchenphysik   /
>>>> /  hirsch at physik.uni-wuppertal.de
>>>> <mailto:hirsch at physik.uni-wuppertal.de> / dominic.hirschbuehl at cern.ch
>>>> <mailto:dominic.hirschbuehl at cern.ch>       \
>>>> |       office : D.09.22    phone  : 0049 - 202 - 439 - 3751
>>>>          |
>>>> \---------------------------------------------------------------------/
>>>> _______________________________________________
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>>>> https://www.hepforge.org/lists/listinfo/rivet
>>>
>>>
>>>
>>>
>>> —
>>>
>>> Dr. Christian Gütschow
>>>
>>> Department of Physics and Astronomy
>>> University College London
>>> Gower Street
>>> London WC1E 6BT
>>>
>>>> D10 Physics Building
>>>> +44 (0)20 7679 3775
>>>> chris.g at cern.ch <mailto:chris.g at cern.ch>
>>>
>>>
>>>
>>>
>>
>>
>> --
>> Dr Andy Buckley, Lecturer / Royal Society University Research Fellow
>> Particle Physics Expt Group, University of Glasgow
>


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