[Rivet] Rivet and HepMC units [Re: Rivet!!]

[David Grellscheid]

Hi again,

To follow up, I would reconstruct Sercan's observations as follows:

 >>>
 >>> _Rivet 1.3.0 with HepMC_2.03.11 and Boost_1.42_
 >>>
 >>> Leading jet: pT = _7.07939 GeV

The producer was also linked to HepMC 2.03 and implicitly produced 
GEV/MM output. Rivet reads this output and implicitly assumes GEV/MM. By 
accident it works.

 >>>
 >>> _Rivet 1.3.0 with HepMC_2.06.01 and Boost_1.44_
 >>>
 >>> Leading jet: pT = _0.00707939 GeV

The same input file was used, i.e. no unit information available. HepMC 
then assumes its configuration defaults

 >> and includes "--with-momentum=MEV"

Rivet reads the number 7.07939 from the file and is told it's in MeV.
When Rivet prints the number back out, it says (in a way correctly):

 >>> 0.00707939 GeV

Hope that helps,

    David