[Rivet] Rivet with POWHEG-BOX

[Andy Buckley]

Hi Tomas,

Sorry for the delayed reply, I missed this at the time.

I suspect the reason that it only fails on the second event is that we 
use the first event to establish beam particles and energies, so the 
second event is the first one on which an analyze() step failure is 
possible. I'm not 100% certain about that, though.

As for the reason for the failure, I don't know what your analysis 
routine is doing, but it's failing when trying to write out a string 
representation of the particle name. Are you trying to do such a 
printout? You should be able to catch the error, but it'd be reasonable 
for us not to throw such a major error for a (probably) cosmetic 
failure. I will now add the gluon to the list of named particles -- it's 
not currently in there because of Rivet's focus on more physically sound 
post-hadronisation particles, but we already support quark names so it 
makes sense to also know about gluons. I can't guarantee that all 
analyses will work well with parton-level final-states, though -- take care!

Andy


On 14/11/16 14:59, Tomas Jezo wrote:
> Dear Rivet authors,
>
> I'm trying to analyze events generated by POWHEG-BOX using Rivet (rivet
> v2.4.3). I'm using the `HepMC::IO_HEPEVT` to convert the events from the
> HEPEVT format and them pass them to rivet:
>
> HepMC::GenEvent* evt = hepevtio.read_next_event();
> rivet.analyze(*evt);
>
> Unfortunately i get the following error:
>
> terminate called after throwing an instance of 'Rivet::PidError'
>   what():  Particle ID '21' not known.
>
> starting from event 2 (event 1 succeeds).
>
> If I write events into a file I get:
>
> HepMC::Version 2.06.09
> HepMC::IO_GenEvent-START_EVENT_LISTING
> E 1 -1 -1.0000000000000000e+00 -1.0000000000000000e+00
> -1.0000000000000000e+00 0 0 1 1 2 0 1 1.1406100000000000e+01
> N 1 "0"
> U GEV MM
> V -1 0 0 0 0 0 2 4 0
> P 1 21 0 0 3.4591526030000000e+02 3.4591526030000000e+02 0 -1 0 0 -1 0
> P 2 21 0 0 -4.2588502149999999e+02 4.2588502149999999e+02 0 -1 0 0 -1 0
> P 3 6 -1.4833769729999999e+00 -1.2369079390000000e+02
> 2.3239638199999999e+02 3.1474742459999999e+02 1.7250000000000000e+02 1 0
> 0 0 0
> P 4 -6 -1.2441412769999999e+01 9.4068674470000005e+01
> -3.5206476490000000e+02 4.0337272209999998e+02 1.7250000000000000e+02 1
> 0 0 0 0
> P 5 5 7.2436624820000004e+00 2.2627455149999999e+01
> 3.3183952779999998e+01 4.1087827820000001e+01 4.7500000000000000e+00 1 0
> 0 0 0
> P 6 -5 6.6811272600000002e+00 6.9946643320000002e+00
> 6.5146689540000002e+00 1.2592307260000000e+01 4.7500000000000000e+00 1 0
> 0 0 0
> E 2 -1 -1.0000000000000000e+00 -1.0000000000000000e+00
> -1.0000000000000000e+00 0 0 1 1 2 0 1 1.1406100000000000e+01
> N 1 "0"
> U GEV MM
> V -1 0 0 0 0 0 2 4 0
> P 1 21 0 0 1.5871885349999999e+01 1.5871885349999999e+01
> 6.7434957620000004e-07 -1 0 0 -1 0
> P 2 21 0 0 -2.1900844820000002e+03 2.1900844820000002e+03 0 -1 0 0 -1 0
> P 3 6 -1.3328056880000000e+01 -8.3731995950000009e+00
> -7.8224201930000004e+02 8.0119072280000000e+02 1.7250000000000000e+02 1
> 0 0 0 0
> P 4 -6 2.1782820879999999e+01 1.1731505100000000e+01
> -1.3307128740000001e+03 1.3420749320000000e+03 1.7250000000000000e+02 1
> 0 0 0 0
> P 5 5 -3.3212752330000002e+00 -2.3273609810000000e+00
> -2.7406078330000000e+01 2.8108772790000000e+01 4.7500000000000000e+00 1
> 0 0 0 0
> P 6 -5 -5.1334887599999997e+00 -1.0309445209999999e+00
> -3.3851624520000001e+01 3.4581939450000000e+01 4.7500000000000000e+00 1
> 0 0 0 0
> ....
>
> Same happens when I run rivet from the command line:
> 1.) It succeeds when analyzing individual events (event 1 or event 2)
> 2.) Fails if run with a file containing both
>
> What am I doing wrong? Would you have any advice for me?
>
> Many thanks.
>
> Cheers,
> Tomas
>
> _______________________________________________
> Rivet mailing list
> Rivet at projects.hepforge.org
> https://www.hepforge.org/lists/listinfo/rivet


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