[Rivet] Plots normalized to cross section

[Andy Buckley]

On 15/02/11 17:38, Stefan Prestel wrote:
> Hi all,
> 
> I wanted to ask if it is possible to generate plots normalized to cross
> section for the standard analysis - without changing these. More
> precisely, rather than plotting d\sigma/dO, I would like to look at
> 1/\sigma d\sigma/dO. That would be quite useful for processes where
> k-factors are rather constant over phasespace and well-known, e.g. for
> Drell-Yan with somewhat large cut on the first jet, when comparing LO
> predictions with data.
> 
> Is it possible to tell rivet to produce histograms in 1/\sigma d\sigma/dO
> (or maybe both varieties d\sigma/dO1 and 1/\sigma d\sigma/dO ?)? If not,
> is it likely that such  a feature will be added in a future release?

Hi Stefan,

Rivet leaves it up to the author to decide how to normalise the
analyses, since different experimental analyses do it differently. You
could just use the Analysis::normalize(IHistogram1D*) function, but this
will not account for overflow and underflow entries: better to track the
sum of event weights to pass cuts and scale the histogram by 1/_sumW (or
by 1/sumOfWeights() if there are no cuts to keep track of).

For analyses where the cross-section is required, and hence LO
generators will be wrong by a k-factor, we have the rivet-rescale
script, which allows you to scale AIDA histograms by fixed factors or to
the reference data.

Hope that helps,
Andy

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