[Rivet] CMS RIVET analyses

[Andy Buckley]

On 25/11/13 01:55, Nhan V Tran wrote:
> Hi Andy,
> 
> Thanks again, comments inline.
> 
> On Nov 24, 2013, at 2:13 PM, Andy Buckley wrote:
> 
>> Hi all,
>>
>> A couple more (minor) questions about this analysis:
>>
>> * In the comments it's stated that the Z and W will be selected with pT
>>> 125 GeV, but in the code the cut is placed at 120 GeV: which is correct?
> 
> The comments are wrong, the cut on the W/Z pT > 120.

Cheers, I've tidied that bit up now.

>> * In the W+jet case, the back-to-back requirement was trying to use two
>> constituent charged leptons: there should only be one and I'd have
>> expected the code to segfault when it tried to access the second.
> 
> This might be my own misunderstanding of the WFinder, but I took the l2 to be the neutrino which I used to define the Phi angle between MET and jet.  It's been a while since I did this so I can't now remember why I came to this conclusion.

Maybe Frank S can confirm, but the neutrino should be in the
constituentNeutrinos and only one charged lepton in constituentLeptons.
I checked the WFinder.cc source code and it does look like that's how
it's being filled.

I'm tempted to rename/alias these functions as constituentLepton,
constituentNeutrino (singular) for WFinder, to clarify things. Just in
Rivet 2.x though -- we're done with interface improvements in version 1.

>> And
>> the back-to-back requirements were being applied the wrong way around
>> anyway: I've fixed all these things, but how was the analysis validated?
> 
> The analysis was validated by comparing a sample MC set against the data HepMC but I guess the sample was pretty small unfortunately.

No problem, just checking. I think we're ready for release now.

Andy


>> Since there was a request to know what CMS analyses are just about to
>> appear in the next Rivet version, I thought I'd also point out that we
>> have three "preliminary" CMS analyses in the code which it would be
>> great to upgrade to their published equivalents:
>>
>> if ENABLE_PRELIMINARY
>> RivetCMSAnalyses_la_SOURCES += \
>>    CMS_QCD_10_024.cc \
>>    CMS_2012_PAS_FWD_11_003.cc \
>>    CMS_2012_PAS_QCD_11_010.cc
>> endif
>>
>> Any chance that you could get these ones to us (or if they are already
>> fine other than the name and ref data, let us know the Inspire IDs).
>>
>> Thanks again,
>> Andy
>>
>>
>>
>> On 22/11/13 20:37, Hannes Jung wrote:
>>> Dear Nhan (cc Andy et al)
>>>
>>> I just forward this mail thread to our Rivet coordinators  Lars & Albert
>>>
>>> Cheers
>>> Hannes
>>>
>>> On 22.11.2013, at 18:16, Nhan V Tran <ntran at fnal.gov> wrote:
>>>
>>>> Hi Andy,
>>>>
>>>> Thanks for the detailed reply!  More inline...
>>>>
>>>>>> Thanks for following up on the CMS jet mass RIVET routine last week.  I forgot to ask you, one of the other CMS conveners was asking me...
>>>>>>
>>>>>> Can you let me know what CMS analyses are in the RIVET queue and what's the expected time to be included?
>>>>>
>>>>> Hi Nhan, (and CC'ing the Rivet dev list)
>>>>>
>>>>> I finally got time today to really spend some time on incorporating the
>>>>> various new analyses for Rivet 1.8.4. We'll release this very soon,
>>>>> followed as soon as we can by an equivalent 2.0.1.
>>>>>
>>>>> There are two CMS analyses in our queue: your jet mass one, and
>>>>> CMS_2013_I1258128.cc (rapidity distributions in Z+jet and gamma+jet
>>>>> events). If there are more that we can include right away, now is the
>>>>> time to let us know!
>>>>
>>>> Thanks, will let you know if there are any other CMS requests.
>>>>
>>>>> I have a few questions/comments about your analysis, actually: we don't
>>>>> just copy them into place but do a bit of code checking and clean-up
>>>>> first... which is why it's usually not a 100% straightforward operation.
>>>>> A bit annoying, I know, but once we've got them in the system we have to
>>>>> maintain them... hence we sometimes ask for fixes and clarifications!
>>>>> Ok, here goes:
>>>>
>>>> Thanks for taking the time.  This is our first RIVET analysis, so I'm very happy to have an expert take a look ;)...
>>>>
>>>>> * I've split the analysis into three separate analyses, with _ZJET,
>>>>> _WJET, and _DIJET suffixes. The _ZJET one is the one that I've tidied up
>>>>> so far (e.g. putting the pT bin searching into a function really
>>>>> compresses the code blocks for the three jet types), and I've attached
>>>>> it for your interest. (It quite possibly doesn't compile right now: it's
>>>>> the code logic that I'd like feedback on, if you have any.)
>>>>
>>>> This is perfect for me. 
>>>>
>>>>> * 2D histos will coming soon in Rivet v2 / YODA. They are an order of
>>>>> magnitude more fiddly than 1D ones, if you really want to handle
>>>>> overflows and so-on nicely. I though that they worked already in Rivet
>>>>> v1, though... but HepData doesn't (yet) support them so I think this 1D
>>>>> slice approach is better anyway.
>>>>
>>>> I agree, it's fine to keep the 1D slides.  
>>>>
>>>>> * There is a bit of code to treat any negative weights as equivalent to
>>>>> 1.0. Why is that? I expect it's a bad idea, especially with more NLO
>>>>> simulations becoming normal, but I wanted to check rather than just
>>>>> remove it.
>>>>
>>>> I think it's fine to remove.  I'm not sure if it was there for some protection (Sal put this in), but you make a good point about the NLO simulations.
>>>>
>>>>> * The back-to-back requirement between the W/Z and the leading jet i
>>>>> actually applied in reverse:
>>>>>
>>>>> // Get the leading jet and make sure it's back-to-back with the Z
>>>>> const fastjet::PseudoJet& j0 = psjetsCA8_zj[0];
>>>>> if (!isBackToBack_zj(zfinder, j0)) { //< @todo ARGH!?!
>>>>>
>>>>> (This is my tidied version of the code, but I checked that this isn't a
>>>>> problem that I introduced!) Is this a (repeated) typo, or is the
>>>>> back-to-back cut *really* meant to work this way round? (Which would be
>>>>> strange.) The isBackToBack function contents do match its name.
>>>>
>>>> Good catch, please reverse it! 
>>>>
>>>>> * Lastly, something on which we'll maybe need input from other Rivet
>>>>> developers: you're using explicitly FastJet3 functionality to groom the
>>>>> jets. That's great: you've written the first official experiment Rivet
>>>>> analysis to require FJ3! But it means that we will need to require FJ3
>>>>> for any Rivet version which includes this analysis... which we currently
>>>>> don't do. I think we can happily do that for Rivet version 2, but
>>>>> perhaps it's not the best idea to make that change in our last ever 1.x
>>>>> minor version.
>>>>>
>>>>> I suggest that we release Rivet 1.x with the existing FJ > 2.x
>>>>> requirement, and also make your analysis code public on the Rivet
>>>>> website for FJ3 users to build. Or we could make a special exception and
>>>>> build the analysis only if FJ2 is present: that might be the neatest
>>>>> option. For Rivet 2.0.1 we can make FJ3 a build requirement: I think it
>>>>> is time for that anyway, but thanks for giving us a concrete reason to
>>>>> do so!
>>>>
>>>> I have seen the continuing thread from the other developers and your solution sounds good for me
>>>>
>>>> Thanks a lot!
>>>> Best,
>>>> Nhan
>>>>
>>>>
>>>>>
>>>>> Cheers, and please let me know about those queries in the code and if
>>>>> you have any other feedback on the "tidied" version: once I know what to
>>>>> do I'll carry on doing similar tidying for the _DIJET and _WJET source
>>>>> files.
>>>>>
>>>>> Andy
>>>>>
>>>>> -- 
>>>>> Dr Andy Buckley, Royal Society University Research Fellow
>>>>> Particle Physics Expt Group, University of Glasgow / PH Dept, CERN
>>>>> <CMS_2013_I1224539_ZJET.cc>
>>>>
>>>> _______________________________________________
>>>> Rivet mailing list
>>>> Rivet at projects.hepforge.org
>>>> http://www.hepforge.org/lists/listinfo/rivet
>>>
>>> ***********************************************************************
>>> Hannes Jung 
>>> Email: Hannes.Jung at desy.de 
>>> mobile :+49 40 8998 93741
>>> http://www.desy.de/~jung                                  
>>> Tel: +49 (0) 40 8998 3741         
>>> Fax: +49 (0) 40 8994 3741
>>> DESY, CMS 01B/02.213
>>> Notkestr.85, 22603 Hamburg, FRG   
>>> ***********************************************************************
>>>
>>>
>>>
>>>
>>>
>>
>>
>> -- 
>> 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