[Rivet] cross-sections in Rivet

[Sercan Sen]

Dear all,

We run EPOS generator on mcplots but having a normalization issue. Probably, this is only a matter of units since the difference with the data is ~10^9. Please see the plot attached where the histograms are scaled as "scale(histogram, crossSection()/millibarn/sumOfWeights())" in Rivet.

If I look at the HepMC output of EPOS, I see that the cross-section is stored as "mb" while it is "pb" in pythia6 HepMC (2.06.08) output.  ("pb" is fine according to the HepMC > 2 manual).

I think, Rivet expects to find the cross-section information in "pb" ? If yes, this problem should be fixed in EPOS HepMC interface, right ? or is there any other solution can be provided by Rivet side ?

================================================
eposPath = /afs/cern.ch/sw/lcg/external/MCGenerators_hepmc2.06.08/epos/1.99.crmc.v2975/x86_64-slc5-gcc43-opt

EPOS output:
HepMC::Version 2.06.08
HepMC::IO_GenEvent-START_EVENT_LISTING
E 0 -1 -1.0000000000000000e+00 -1.0000000000000000e+00 -1.0000000000000000e+00 0 0 316 1 2 0 0
U GEV MM
C 7.2458518981933594e+01 0.0000000000000000e+00

------------------

agilePath = /afs/cern.ch/sw/lcg/external/MCGenerators_hepmc2.06.08/agile/1.4.0/x86_64-slc5-gcc43-opt
agile-runmc Pythia6:424 --beams=LHC:7000 -n ${NOE} -o output.hepmc
HepMC::Version 2.06.08
HepMC::IO_GenEvent-START_EVENT_LISTING
E 2 -1 -1.0000000000e+00 -1.0000000000e+00 -1.0000000000e+00 0 0 195 1 2 0 1 1.0000000000e+00
N 1 "0"
U MEV MM
C 4.8444950025e+10 4.8444950025e+10
================================================


Thanks in advance,

Cheers,
Sercan



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