[Rivet] New LHCB analysis --- definition of z_0

[Holger Schulz]

On 04/11/15 14:18, David Grellscheid wrote:
>>> Isn't Beams::IP always going to be (0; 0,0,0)? We used to have a
>>> PrimaryVertex projection and it was totally pointless.
>>
>> I'd still leave it in. ThePEG can generate IP offsets (although nobody
>> uses them), and I could imagine other situations that we shouldn't lock
>> out.
>
> Let me clarify why for once I'm in favour of a (slightly) more 
> complicated option: the fact that all current generators produce 
> (0,0,0,0) here is not enforced by any of the tools we use upstream, 
> it's just a coincidence. HepMC allows any value in that field, so we 
> should be able to handle any value there.
>
>   David
> _______________________________________________
> Rivet mailing list
> Rivet at projects.hepforge.org
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I have boiled down their code to these two lines of HepMC stuff:

    const HepMC::GenVertex* vtx = p.genParticle()->production_vertex();
    Vector3 d(vtx->position().x(), vtx->position().y(),
    vtx->position().z());

It's not perfect but it's just two lines that hardly justify changes to 
the Particle class.
I will put it into rivet like this now.

A validation plot is attached.

Thanks,
Holger




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