[Rivet] Access to transverse and longitudinal impact parameters

[Leif Lönnblad]

Hi Marcus,

The impact parameter is an optional piece of information that can be 
added to HepMC via the HeavyIon class. As such it can be accessed in the 
Rivet::Event object by going through the genEvent() function to the 
underlying GenEvent object.

Note, however, that the impact parameter is not an observable, and it is 
not advisable to build rivet analyses requiring this. To avoid model 
dependencies, the preferred way of doing it is to infer the impact 
parameter, or rather the centrality, from actual observables in the same 
way as is done in the experimental analysis.

Cheers,
Leif


On 2014-07-07 13:28, Markus Radziej wrote:
> Hi,
>
> I was wondering if there is some way to access the impact parameter
> information via Rivet? I have tried looking into other analyses, but
> could not find one that works with these variables. I'm not quite sure
> the information even exists, so I decided to write an email.
>
> Thanks for your help,
> Markus Radziej
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