[Rivet] Rivet analysis OPAL_2004_S613224

[Christoph Pahl]

Hello Andy, Peter and all rivet developpers,

we would be happy if the OPAL 2004 Rivet analysis could in fact be used. 
We are still using the analysis code (working with Nadine Fischer led me 
back to this problem) and we have all data and MC samples.

The exclusion resulted from Peter Skands stating
http://www.hepforge.org/lists-archive/rivet/2011-May/002220.html
large deviations ~ factor 3 between data and rivet PYTHIA results in (for 
example) the lowest 1-thrust bin for OPAL at 91 GeV, but not for ALEPH.

The linked plots are hard to read as they are very dense, and the 
ratios go only up to 1.5 . From the numbers on the cited web page I 
calculate the deviation more precisely as 2.5; and from the ALEPH plot I 
see a HERWIG deviation in this bin of ~ 2, shouldn't you then exclude
ALEPH as well?
The lowest bin has experimental and theoretical difficulties and we never 
include it in any fitrange. So excluding an analysis because of a problem
there is pretty sad. But as soon as I understand the problem better I can 
of course compare our code with the rivet analysis.


On Mon, 21 Oct 2013, Andy Buckley wrote
> In particular, as part of the histogramming migration to Rivet 2.0, we
> did discover some issues with the definition of _integrated_ jet rates
> in the JADE_OPAL analysis. Depending on whether the integral is taken up
> to the midpoint of the bin, the low edge, or the upper edge you can get
> quite different answers. I am not sure which is correct for that
> analysis -- are you? -- but the differential rates should be correct.
> Please let us know if you've got any ideas or questions about this.

Stefan Kluth told me that OPAL always employed the bin midpoint to 
represent the point where the jet rate had been evaluated.

Best regards,
Christoph