[Rivet] Is it possible? Rivet and truth look different

[Andy Buckley]

On 07/11/13 09:48, Liron Barak wrote:
> Hi Andy,
> 
> Now that Rivet is working for me, thanks!
> I see something weird....
> I took the official sherpa samples (made by sherpa 1) and compared to my
> private sherpa2 samples... I used MC_TTBAR in river to compare (with
> evgens) and simple Draw of the truth jet branch with the truthD3PDs I
> made...
> Please see the attached.... the Jet_N for both samples behave opposite
> in the 2 plots, no?

Hi Liron,

Can you check if there is lepton/jet isolation in the ROOT analysis? In
Rivet we make jets from *everything* provided to the FastJets, so hard
leptons will count as jets unless they are identified and removed.

This is something which would be nice to improve, as is the definition
of jet inputs, but unlike the ATLAS truth jets we need to be generic
rather than expt-specific. I hope we'll provide an AtlasJets projection
to make this easier at some point, but even ATLAS itself doesn't have a
single truth-jet constituent definition yet!

Andy

-- 
Dr Andy Buckley, Royal Society University Research Fellow
Particle Physics Expt Group, University of Glasgow / PH Dept, CERN