[Rivet] normalisation to cross-sections

[Hendrik Hoeth]

Hi,

I really don't want to be the killjoy, but I'd like to suggest that
before we blindly start converting all our analyses to cross-section
normalisation only because that is nice, new, and nifty, we should
go through the painful procedure of switching on the brain and think
for a moment what makes sense and what doesn't. In fact, that's why
I hadn't commented on this discussion so far -- too much painful brain
activity needed.

But let's do it for a moment. Things like a 1-Thrust certainly don't
need to be normalised to anything other than 1. There is no such thing
as cross-section information in an event shape. Looking at the list of
analyses touched in r1953 the only one I recognise immediately is
D0_2004_S5992206. I don't know what the other analyses are, but the 2004
measurement is the di-jet angular distribution thingy which we use in
the tuning all the time. That's an event shape measurement. The area of
those data histograms is 1, and that's what they should be normalised
to.

The same applies to observables like the scaled energy in
D0_1996_S3214044, or to the cos(theta_something) distributions. Please
don't apply cross-section normalisation to such observables. In fact,
probably it applies to all distributions in the D0_1996_S3214044
publication, I didn't have a close look, but the fact that all data
histograms have area=1 points in that direction.

Again, I don't know the other analyses in that list, and I didn't look
them up, but please let us go through whatever analyses we want to
change _thoughtfully_. And add the "setNeedsCrossSection(True)" only if
needed.

Cheers,

     Hendrik

> Modified:
>    trunk/data/plotinfo/D0_1996_S3214044.plot
>    trunk/data/plotinfo/D0_1996_S3324664.plot
>    trunk/data/plotinfo/D0_2004_S5992206.plot
>    trunk/data/plotinfo/D0_2007_S7075677.plot
>    trunk/data/plotinfo/D0_2008_S6879055.plot
>    trunk/data/plotinfo/D0_2008_S7554427.plot
>    trunk/data/plotinfo/D0_2009_S8320160.plot
>    trunk/src/Analyses/D0_1996_S3214044.cc
>    trunk/src/Analyses/D0_1996_S3324664.cc
>    trunk/src/Analyses/D0_2004_S5992206.cc
>    trunk/src/Analyses/D0_2007_S7075677.cc
>    trunk/src/Analyses/D0_2008_S6879055.cc
>    trunk/src/Analyses/D0_2008_S7554427.cc
>    trunk/src/Analyses/D0_2009_S8320160.cc

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