[Rivet] DIS issues with Rivet

[Andy Buckley]

On 08/08/12 17:30, Roman Kogler wrote:
> Hi Andy,
> 
> thanks for following up on that. You are right - the concerns from
> Thomas and Simon overlap with my previous emails. In fact, I think we
> are going to work together with implementing and testing some DIS analyses.
> 
> I have a few patches for the DIS case, how should I send them to you?
> Would you like me to implement them directly or should I just send you
> some code snippets that you or one of the Rivet team has to implement?

Patches w.r.t the latest release or trunk would be best.

> In fact, how are you validating changes and new developments in Rivet?
> Do you have a standard validation procedure?

Other than by code inspection and a bit of awareness of the physics, our
validation is done before each release with the mcplots.cern.ch system.
But that doesn't include any DIS observables/analyses at present, so
this will need a bit more care.

> I'm asking because one of
> the changes concerns the recombination scheme of the jet finder. In DIS
> we use the pt-recombination scheme which gives different results than
> the LHC-standard fourvector recombination (E-scheme). Here I would
> propose to take the jet four-vector directly from FastJet instead of
> recalculating it in Rivet, as is done at the moment.

Hmm, I thought I had removed the (yes, bad!) momentum recalculation a
couple of versions ago. Is that definitely still the case in 1.8.0 / 1.8.1?

> To test these
> changes it would be good to run some sort of validation and make sure
> that for the Tevatron or LHC jet analysis nothing changed.

That should be checked by the mcplots test.

> Otherwise, it would be great if the fixes for the DIS case could go into
> a public release soon. This will make it much easier for us to implement
> some analyses.

Ok, I'm pretty sure we can help, given the necessary code! But just
*maybe* the most important change to the Jet class has already been done...

Andy


> On 8/7/12 18:13, Andy Buckley wrote:
>> On 07/08/12 17:01, Simon Plätzer wrote:
>>> Hi Andy,
>>>
>>> some time ago Thomas and colleagues asked about few issues related to
>>> DIS analyses in Rivet. We really want to look at these/use the provided
>>> features to implement other DIS observables; have you had time to look
>>> into this stuff?
>> Hi Simon,
>>
>> I'm replying with the Rivet mailing list in CC, since I think no-one has
>> the capacity to be 100% in charge of Rivet development at the moment
>> (roll on yet another attempt at EU funding...)
>>
>> I spoke with Roman (also in CC now) at the BOOST workshop about some
>> improvements to the DIS treatment, and confirmed there that while *I*
>> don't have time to implement them, we will ecstatically receive,
>> integrate and credit any patches that you, Thomas or Roman should
>> supply! DIS isn't an event type that many people are testing right now,
>> so if you guys have the interest then I think you are the best possible
>> critics and improvers (I don't want to say "maintainers" -- it implies
>> drudgery!)
>>
>> I don't recall if Thomas and Roman's concerns/suggestions overlap,
>> although I guess all you guys are in (actual, same-institute type)
>> contact? The main development thread in Rivet at the moment is the big
>> histogramming (and other things) overhaul, which I hope will be ready
>> for a first release in a couple of months -- faster seems too
>> optimistic. But we have a maintenance branch and can consider a 1.8.2
>> release in the next month or so if there is enough development to
>> warrant it.
>>
>> Thanks,
>> Andy
>>
> 
> 


-- 
Dr Andy Buckley, SUPA Advanced Research Fellow
Particle Physics Expt Group, University of Edinburgh

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