[Rivet] CDF run1 pT spectrum analysis

[Frank Siegert]

Hi Holger,

Holger Schulz, Monday 07 June 2010:
> today I noticed that the CDF_1988.... analysis is sort of
> broken. It's the one that has the Run I pT spectra in it.
> 
> For some reason, I get negative bin-contents throughout.
> I guess the likely culprit is this line in finalize:
> 
>     scale(_hist_pt, crossSectionPerEvent()/millibarn);

I can't see how that would make anything negative. 
crossSectionPerEvent() is crossSection()/sumOfWeights(), if any of these 
is negative, that's a problem in the generator.

Frank