[Rivet] Born and dressed level in Rivet

[Ulla Blumenschein]

Hi David,

We didn't identify the FSR photons experimentally but we unfolded to a
reference where a  lepton was dressed with the respective technical
FSR implementation. We checked that we get a similar correction in the
standard generators, (pythia, herwig, sherpa..). It makes sense to
adopt the new convention but we should check the backwards
compatibility. Judging from the tests so far we did when publishing a
new rivet routine we don't expect large differences.

Cheers, Ulla

On Tue, Oct 8, 2013 at 10:36 AM, David Grellscheid
<david.grellscheid at durham.ac.uk> wrote:
> Hi Tim,
>
>> However the issue here is that we have many measurement which did use
>> only identified FSR photons in their dressing cones.
>
> If there is a procedure by which you can identify FSR photons in
> experimental data, it can be used in Rivet. That operational definition
> of FSR would then differ from truth-FSR in the same way that the
> operational definition of a gluon jet is not the same thing as a jet
> coming from an MC-truth gluon.
>
> The usual classification that MC generators make into ISR and FSR is a
> purely technical convenience in the codes, with no physical reality, as
> Jon was saying. This makes it very dependent on the actual generator
> used, and impossible to implement sensibly in Rivet.
>
>   David



-- 
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    Ulla Blumenschein
    II Physik, Uni Goettingen
    Friedrich-Hund-Platz 1, D01.110
    phone: 0049-551-397645
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