[Rivet] CMS RIVET analyses

[Andy Buckley]

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?

* 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. 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?

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