[Rivet] Born and dressed level in Rivet

Ulla Blumenschein ublumenschein at googlemail.com
Thu Oct 3 17:39:03 BST 2013
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Hello Oleg,

would be great, if you could test the new proposed dressed-definition
vs the FSR-only option, just to make sure we don't miss anything
unexpected. But  I second Tim, currently I can also not think of any
further substacial contribution. (Have to cross check some slides
which Evelin had shown a year ago..)

Cheers, Ulla

On Thu, Oct 3, 2013 at 6:03 PM, Oleg Zenin <ozenin at cern.ch> wrote:
> Dear All,
>
>
> On Thu, 3 Oct 2013, Ulla Blumenschein wrote:
>
>> 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.
>
>
> Yes, we are reading standard evgen ROOT files and can implement any
> logic of lepton&photon selection. For the moment, three variants of
> truth Z reconstruction are used in Z UE analysis: Born (via collection of
> the leptons from the hard process + all FSR photons), dressed leptons (two
> leptons from the hard process + all photons within leptons' \Delta R = 0.1
> cones), and leptons dressed by only FSR photons within \Delta R = 0.1.
>
> Regards,
> Oleg.
>
>>
>>
>> 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
>> /_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
>>
>



-- 
/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
    Ulla Blumenschein
    II Physik, Uni Goettingen
    Friedrich-Hund-Platz 1, D01.110
    phone: 0049-551-397645
/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
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