[Rivet] finalstate projection with assymetric beam

[Pierog, Tanguy (IKP)]

	Hi Andy,


> The only existing projection that does that is DISKinematics, I think.
> We could make a projection like you mention, but everything that
> projections do can also be done inside an analysis code, and since there
> has not previously been a request for that functionality there was no
> incentive for us to make a new feature that no-one wanted! But if you
> would find this useful in *several* analyses -- so there is a chance of
> some benefit from result caching as well as simplifying several analysis
> codes -- then we can take this a bit further.
>

	The point is that many fixed target experiments plot the various observables 
in the center-of-mass frame (like rapidity or xf). So yes this will be used 
by several analysis and if you want RIVET to be used not only at LHC (there 
is still a lot of fixed target experiment at SPS or in other lab) this would 
be useful to help these collaboration to include their analysis in RIVET. 
Since we are involved in NA61 for instance I can push my colleagues to put 
their analysis on RIVET for instance.


> We will probably need to iterate a bit to understand how the CoM frame
> is to be defined, and whether it also needs to include some rotation
> into a conventional alignment cf. our built-in HERA transformation.
>

	We can have a look at what is done in DISKinematics and try something 
ourself. It should not be complicated but it would be cleaner to have generic 
projection. In that case the CoM is simple (just the same projectile and 
target but boosted) and there is no a priori convention here (but technically 
the "exotic" particle is always the projectile but it is the same in the 
models).


> > 	Actually I have the same question about the analysis we are doing. They
> > are based on old data (80's and 90's) from collaboration which are not
> > existing anymore. What is the policy in that case. Can it be distributed
> > or should it get some approval from someone ? Do you have any idea ?
>
> We don't enforce a policy about analyses needing to be approved by
> experiments, particularly not defunct ones. We just much *prefer* that
> analyses being provided during an experiment's lifetime be written, or
> at least be approved by that experiment, but an unofficial analysis is
> far better than nothing. We'll happily take anything you provide!
>

	OK thanks. For the moment it is just a topic for bachelor student, but we 
find manpower we would like to increase our data base and why not putting it 
online.

	best regards

		Tanguy
-- 

_________________________________________________________________________
Dr. Tanguy Pierog, Institut fuer Kernphysik, Campus Nord
Karlsruher Institut fuer Technologie,  Postfach 3640,  D-76021 Karlsruhe,  
Germany
Tel: +49-721-608-2-8134  Fax: +49-721-608-2-4075  e-mail: 
tanguy.pierog at kit.edu
KIT - University of the State of Baden-Wuerttemberg and 
National Laboratory of the Helmholtz Association