[Rivet] Born and dressed level in Rivet

[Tim Martin]

Hi Ulla,

He might be able to. I'm not sure what Oleg's setup is / how trivial
this would be in terms of development and grid time.

If there is still found to be a a non-negligible difference between
only-FSR-photons and photons-without-status-2-hadron-or-tau-parent
then this new definition may not be deemed a useful enough addition to
warrant the change, but honestly - how many other photon sources are
there which could get us here! :)

Cheers, Tim.

On 3 October 2013 16:44, Ulla Blumenschein <ublumenschein at googlemail.com> wrote:
> Hi Tim,
>
> would Oleg also be able to plot the difference btw FSR only and the
> new proposed definition for high sumpT and high ZpT?
>
> Cheers,
> Ulla
>
> On Thu, Oct 3, 2013 at 5:40 PM, Tim Martin <tim.martin at cern.ch> wrote:
>> Thanks,
>>
>> A flag in the W/ZFinder constructor which is passed on to
>> ClusteredPhotons sounds like a good solution to me. Giving the option
>> to use this slightly more involved but more technically correct
>> version excluding photons from hadronisation and beyond.
>>
>> We could then reassess on a case-by-case basis if we want to modify
>> some of our current Rivet analyses which corrected to a only FSR
>> photons definition.
>>
>> Oleg has shown the difference between all photons and FSR only can be
>> up to ~3% in some variables for more extreme phases spaces, so high
>> pTz or with around 100 GeV of hadronic activity in the vicinity of the
>> Z.
>>
>> Thanks, Tim.
>>
>> On 3 October 2013 16:28, Ulla Blumenschein <ublumenschein at googlemail.com> wrote:
>>> Hi Andy,
>>>
>>> Many thanks for the feedback.
>>> Yes, what you detail sounds as good as we can get.
>>> Excluding the photons from any hadron decay chain, would be desirable.
>>>
>>> We would have to talk to SM subconveners and conveners of course to
>>> discuss the approach.
>>> As far as I know Oleg is running on standard evgen files or even
>>> ntuples, so I think he has all the flexibility to mimick both
>>> definitions, I hope.
>>>
>>>
>>> Cheers,
>>> Ulla
>>>
>>>
>>>
>>> On Thu, Oct 3, 2013 at 5:19 PM, Andy Buckley <andy.buckley at cern.ch> wrote:
>>>> On 03/10/13 17:00, Ulla Blumenschein wrote:
>>>>> Dear Andy,
>>>>>
>>>>> I  would be very happy if that works out.
>>>>> I cc to Oleg  and Tim, who did a comparison of various dressing
>>>>> definitions recently.
>>>>> Maybe Oleg would be interested to reproduce his plots with the
>>>>> proposed new Rivet implementation, to check what the residual effect
>>>>> is of the missing " from W/Z" requirement.
>>>>
>>>> I can certainly tell you how to hack an existing Rivet version to do
>>>> that. It's a bit low-level, though, so not obvious to me how it would be
>>>> done inside a particular analysis. But contact me/us and we'll do what
>>>> we can to help.
>>>>
>>>>> I have a technical question: Would only photons dircetly from
>>>>> quarkonia decays be excluded?  Where would photons from leptons from
>>>>> semileptonic HF decays end up?
>>>>
>>>> Our fromDecay(Particle&) function walks back up the decay chain looking
>>>> for a parent hadron or tau with status=2, meaning "physical hadron/tau
>>>> which has already been decayed". (Note the double specification: PYTHIA6
>>>> predates the standard status codes so we overspecify!) So photons from
>>>> charmonia and from hadron decay leptons would count as being from
>>>> decays: I assume that is what you want? Special case treatments for
>>>> these would take more coding, but if it'll be needed then we should know
>>>> now: at the very least this would indicate that the steering flag needs
>>>> to have more states than a bool would allow!
>>>>
>>>> Of course this would mean that the ClusteredPhotons projection would
>>>> need to be configured differently for charmonia analyses than for W/Z
>>>> ones, but that is hardly surprising. And we can leave the flag as
>>>> "include all" by default on ClusteredPhotons, but turn it to "non-decay
>>>> only" by default for the W/ZFinders. Sound good?
>>>>
>>>> Andy
>>>>
>>>>
>>>>
>>>>> On Thu, Oct 3, 2013 at 3:16 PM, Andy Buckley <andy.buckley at cern.ch> wrote:
>>>>>> Hi Ulla, all,
>>>>>>
>>>>>> I've discussed this a bit with Daniel Froidevaux and think that it would
>>>>>> make sense for us to at least add a flag to the ClusteredPhotons tool in
>>>>>> Rivet to exclude photons which come from hadron decays. Taus are a bit
>>>>>> of a borderline case, but that does not affect (current) EW measurements.
>>>>>>
>>>>>> This is not *exactly* the same definition, but I think that "only
>>>>>> photons from W/Z" is hard to implement in a generator-unspecific way.
>>>>>>
>>>>>> Maybe Frank Siegert wants to comment more on this proposal to use the
>>>>>> fromDecay() function in ClusteredPhotons, since he did most of the
>>>>>> detailed work to put these W/ZFinders and related classes together.
>>>>>>
>>>>>> Re. the Born comparisons, I believe that the ATLAS W/Z analyses written
>>>>>> so far *don't* compare to the Born-level results, since there *isn't* a
>>>>>> generator-portable way to write them. I remember removing a
>>>>>> generator-specific code along those lines in a previously submitted
>>>>>> analysis for that reason: it's fine for ATLAS-internal versions of
>>>>>> analyses but won't go into the public Rivet library.
>>>>>>
>>>>>> Hope that helps,
>>>>>> Andy
>>>>>>
>>>>>> PS. For those who care, if we agree that that is a reasonable route, I
>>>>>> propose that the exclude-decay-photons functionality would go into Rivet
>>>>>> 2.0.1 or 2.0.2. The exact version depends on the extent to which we want
>>>>>> to separate different types of change -- 2.0.1 might just be adding some
>>>>>> "queued" analysis codes, or it could be a combination of that and some
>>>>>> definition changes. The numbering does not really reflect anything about
>>>>>> the timescales! But note that we'll only be making this change in the
>>>>>> Rivet 2 series -- 1.x is in "maintenance mode".
>>>>>>
>>>>>>
>>>>>> On 03/10/13 14:51, Roman Lysak wrote:
>>>>>>>
>>>>>>>  Hi Ulla,
>>>>>>>
>>>>>>> I think the Rivet authors are better to replay to your questions so I'm
>>>>>>> cc-ing this to them.
>>>>>>> Could anyone address Ulla's questions?
>>>>>>>
>>>>>>> Cheers,
>>>>>>>   Roman
>>>>>>>
>>>>>>> On 10/03/2013 12:25 PM, Ulla Blumenschein wrote:
>>>>>>>> Hi Roman,
>>>>>>>>
>>>>>>>> we have currently a discussion in SM about how to synchronize  the
>>>>>>>> Atlas internal definition of dressed leptons with the Rivet
>>>>>>>> implementation.
>>>>>>>> Currently in SM, we sum all photons emitted from the W/Z decay
>>>>>>>> products whereas Rivet sums all photons.
>>>>>>>> With the extreme phase spaces which we access with 8TeV there are
>>>>>>>> differences up to percentage level between these definitions due to
>>>>>>>> pi0 decays from hadronic activity close to leptons.
>>>>>>>>
>>>>>>>> Is it possible to  implemet an alternate Z finder which can
>>>>>>>> discriminate photon sources? I understand that this might be against
>>>>>>>> the philosophy of Rivet (MC independence). Or are there other
>>>>>>>> problems?
>>>>>>>>
>>>>>>>> Also the born level Z finder is not completely clear to me. I assumed
>>>>>>>> so far that the born level is defined by different status codes in
>>>>>>>> different MC generator, so how does Rivet handle this issue?
>>>>>>>>
>>>>>>>>
>>>>>>>> Many thanks in advance,
>>>>>>>> Ulla
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> On Sun, Sep 15, 2013 at 7:46 PM, Roman Lysak <lysak at fzu.cz> wrote:
>>>>>>>>>   Hi Ulla,
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On 09/12/2013 06:51 PM, Ulla Blumenschein wrote:
>>>>>>>>>> Hi Roman,
>>>>>>>>>>
>>>>>>>>>> Could you explain how we define Born and dressed in a generator
>>>>>>>>>> independent way in Rivet?
>>>>>>>>>
>>>>>>>>> it depends on the object type.
>>>>>>>>> For example, for Z boson (similarly for W boson), you can specify
>>>>>>>>> whether to
>>>>>>>>> add photons (next to last one parameter in the constructor below) in
>>>>>>>>> a given
>>>>>>>>> radius (2nd next to last one parameter) around the leptons from Z
>>>>>>>>> decay to
>>>>>>>>> the Z boson 4-momentum.
>>>>>>>>>
>>>>>>>>>        //fiducial phase space + born level
>>>>>>>>>        ZFinder zfinder_mu(-2.4, 2.4, 20, MUON, 66.0*GeV, 116.0*GeV, 0.1,
>>>>>>>>> false, false);
>>>>>>>>>        addProjection(zfinder_mu, "ZFinder_mu");
>>>>>>>>>
>>>>>>>>>        //for combined cross-sections (combined phase space + dressed
>>>>>>>>> level)
>>>>>>>>>        ZFinder zfinder_comb_mu(-2.5, 2.5, 20, MUON, 66.0*GeV,
>>>>>>>>> 116.0*GeV, 0.1,
>>>>>>>>> true, false);
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Sorry for late response.
>>>>>>>>>
>>>>>>>>> Cheers,
>>>>>>>>>    Roman
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>> Cheers, Ulla
>>>>>>>>>>
>>>>>>>>>> /_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
>>>>>>>>>>       Ulla Blumenschein
>>>>>>>>>>       II Physik, Uni Goettingen
>>>>>>>>>>       Friedrich-Hund-Platz 1, D01.110
>>>>>>>>>>       phone: 0049-551-397645
>>>>>>>>>> /_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
>>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> Rivet mailing list
>>>>>>> Rivet at projects.hepforge.org
>>>>>>> http://www.hepforge.org/lists/listinfo/rivet
>>>>>>
>>>>>>
>>>>>> --
>>>>>> Dr Andy Buckley, Royal Society University Research Fellow
>>>>>> Particle Physics Expt Group, University of Glasgow / PH Dept, CERN
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>> --
>>>> Dr Andy Buckley, Royal Society University Research Fellow
>>>> Particle Physics Expt Group, University of Glasgow / PH Dept, CERN
>>>
>>>
>>>
>>> --
>>> /_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
>>>     Ulla Blumenschein
>>>     II Physik, Uni Goettingen
>>>     Friedrich-Hund-Platz 1, D01.110
>>>     phone: 0049-551-397645
>>> /_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
>>
>>
>>
>> --
>> -+-+-+-+ Tim Martin +-+ ATLAS +-+-+-+-
>> Room 448A, University of Warwick, CV47AL
>> Tel: (+44) 0-24761-51769
>> Web: http://Tim-Martin.co.uk
>
>
>
> --
> /_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
>     Ulla Blumenschein
>     II Physik, Uni Goettingen
>     Friedrich-Hund-Platz 1, D01.110
>     phone: 0049-551-397645
> /_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/



-- 
-+-+-+-+ Tim Martin +-+ ATLAS +-+-+-+-
Room 448A, University of Warwick, CV47AL
Tel: (+44) 0-24761-51769
Web: http://Tim-Martin.co.uk