[Rivet] Minor analysis changes

[Gavin Hesketh]

Hi Frank,
yes, exactly. You process individual samples with different # partons in 
the final state all the way through pythia, rivet. Then (manually) 
weight them to the same lumi and add together. So, (Z+j)/(Z) comes from

a.(Z+j)1 + b.(Z+j)2 +...
------------------------
a.(Z)1   + b.(Z)2 + ....

where a,b are the lumi weights, (XX)1, 2 are from the samples with 
different partons. If all you have is [(Z+j)/(Z)] for each of these 
parton samples, I haven't figured out a way to do this...

cheers,
	Gavin

On 04/01/11 14:50, Frank Siegert wrote:
> Hi Gavin,
>
> On 04/01/11 14:23, Gavin Hesketh wrote:
>> A request: there are several analyses the plot differential cross
>> sections like sigma(Z+jet) / sigma (Z). It would be very useful to also
>> store sigma(Z) for these analyses (this is actually essential
>> information to uses these analyses with alpgen).
>
> Could you explain that a bit further? Do you need this to add up the (in
> Alpgen) separate multiplicity runs manually later on?
>
> Cheers,
> Frank