[Rivet] Promptness of hadrons

[Andy Buckley]

On 03/06/14 18:36, Holger Schulz wrote:
> Hi,
> 
> I am working with a student on the unvalidated LHCB_2012 analysis
> which looks at prompt pions, kaons and protons. It seems as if
> LHCB defines such objects using a cut on the distance from
> the primary vertex.
> 
> I was wondering if there is a preferred way in Rivet (2.1.2) to
> implement this without doing nasty things with the HepMC
> event record.

No, but having an actual use-case right now is a great opportunity to
get that sorted out. "Make some tools to help with hadron decay chains"
has been on my Rivet TODO list forever, but without an itch to scratch
it's hard to usefully imagine what form those tools should take.

I recently added a couple of functions to Particle to help with
identifying all/direct/stable daughters, but I shied away from adding a
decayLength() or flightLength() function because it wasn't obvious to me
what would be the best behaviour if it were called on stable particles
or beam particles... return -1 or throw a UserError exception?

If you don't mind enhancing the 20x branch and working with that
development version for a bit, then it would be really nice to avoid the
HepMC stuff -- and provide a way that we can remove the HepMC nastiness
from a bunch of other LHCb/BELLE/BABAR/ARGUS b/c physics analyses. Run
your thoughts past this email first, though... or push a new head and we
can review and merge: whatever works.

Thanks!
Andy

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