[Rivet] Partonic top support?

[Leif Lönnblad]

Sounds like we more or less agree.

I have a similar issue with the heavy-ion community. I would like to get 
them on board the Rivet philosophy, but they insist on publishing 
results as a function of very model-dependent quantities such as 
'centrality' and 'number of participants'. Such things are available in 
the heavy-ion extension of HepMC.

I think we should try to be be pedagogical here and allow them to 
publish Rivet analyses, but point out very clearly that this is a 
model-dependent measurement. Maybe by simply enforcing the histogram 
names to include the word 'Model Dependent' or something like that. 
Maybe we should also try to enforce that if they publish such 
analysis/data, they must also publish the actual measurement from which 
it is derived.

Rather than just saying no, I think this would be a good way of making 
them see the light ;)

/Leif




On 2016-06-20 22:23, Andy Buckley wrote:
> Hi all,
>
> As we all know, we *massively* favour writing Rivet analyses based on
> post-hadronisation particles. And that approach has had increasing
> purchase in the experiments, with the likes of fiducial "pseudo-top"
> measurements increasing.
>
> But for top analyses in particular, there are many useful analyses that
> rely on parton-level tops. For example, we were sent a CMS analysis a
> few months ago which included a parton-top finder digging around in
> HepMC... and I've not included it in the official analysis collection
> because it doesn't fit with our philosophy. I don't need to repeat the
> many reasons that this approach is suboptimal, but the measurements will
> continue to be made, there is still useful physics in them, and it seems
> unfortunate for Rivet to not be able to include them.
>
> I wonder if this situation is sufficiently nuanced that we should
> swallow our distaste and provide an official "DodgyPartonFinder" to
> avoid repetition of that fragile code? I'd want to make it print out
> some warning messages to flag up the dangerous unportability, and
> clearly mark as dangerous in the .info file of any analysis that uses
> it... but it's still better than needing to maintain n *different*
> implementations of dirty HepMC-walking parton finder algorithms.
>
> I'm convinceable either way, but (as having initiated this thread
> suggests) I'm leaning toward thinking that analysis coverage and
> pragmatism are sufficiently valuable to allow a compromise... in the
> case of top physics.
>
> Thoughts & feelings? I expect controversy -- please deliver ;-)
>
> Andy
>
> PS. As Rivet v3 approaches we also need to develop a plan for how future
> analysis distribution, separated from the core library, can work without
> destroying the quality control that we've made a key feature. Maybe
> we'll grasp that nettle in person in September, but I just note here
> that we could have several "grades" of approval, and hence put partonic
> top top analyses in a "use with caution" category.
>