[Rivet] What's going on with beam energies?

[Andy Buckley]

On 21/01/14 10:16, Leif Lönnblad wrote:
> Hi all,
> 
> Christian, my student, noticed that when running the analysis
> CMS_2011_S8978280 in Rivet 2.0, the histograms filled are always
> compared to the 900 GeV data, even if we're running with 7 TeV. In the
> old version this was handled in the booking of the histograms in init(),
> where sqrtS() was checked and the histograms were booked accordingly. I
> think I localized the change to revision 4013 (by David).
> 
> Now I seem to remember that the beam energy handling was supposed to
> change, and that some of the checking should be done centrally, but I
> can't really find where the booking of histograms would be affected.
> If you agree that this is a bug, I will fix it.

It sounds like a bug: thanks!

> We also noted that when requesting an analysis made at 900 GeV, it is
> not switched off when generating events at 7 TeV, even if
> AnalysisHandler::_ignoreBeams is false. I found the following suspicious
> lines in Analysis.cc:
> 
>     foreach (const DoublePair& ep, requiredEnergies()) {
>       if ((fuzzyEquals(ep.first, energies.first, 0.01) &&
>            fuzzyEquals(ep.second, energies.second, 0.01)) ||
>           (fuzzyEquals(ep.first, energies.second, 0.01) &&
>            fuzzyEquals(ep.second, energies.first, 0.01)) ||
>           ((ep.first - energies.first) < 1*GeV &&
>            (ep.second - energies.second) < 1*GeV) ||
>           ((ep.first - energies.second) < 1*GeV &&
>            (ep.second - energies.first) < 1*GeV)) {
>         beamEnergiesOk =  true;
>         break;
>       }
>     }
> 
> I assume that the four '(blah - duh) < 1*GeV' statements should have an
> "abs" and will fix this if no one objects.

Definitely wrong. I have a feeling that I made that thing. Please fix...
thanks again.

Andy

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