[Rivet] Born and dressed level in Rivet

[Roman Lysak]

  Hi Ulla,

I think the Rivet authors are better to replay to your questions so I'm 
cc-ing this to them.
Could anyone address Ulla's questions?

Cheers,
   Roman

On 10/03/2013 12:25 PM, Ulla Blumenschein wrote:
> Hi Roman,
>
> we have currently a discussion in SM about how to synchronize  the
> Atlas internal definition of dressed leptons with the Rivet
> implementation.
> Currently in SM, we sum all photons emitted from the W/Z decay
> products whereas Rivet sums all photons.
> With the extreme phase spaces which we access with 8TeV there are
> differences up to percentage level between these definitions due to
> pi0 decays from hadronic activity close to leptons.
>
> Is it possible to  implemet an alternate Z finder which can
> discriminate photon sources? I understand that this might be against
> the philosophy of Rivet (MC independence). Or are there other
> problems?
>
> Also the born level Z finder is not completely clear to me. I assumed
> so far that the born level is defined by different status codes in
> different MC generator, so how does Rivet handle this issue?
>
>
> Many thanks in advance,
> Ulla
>
>
>
>
>
> On Sun, Sep 15, 2013 at 7:46 PM, Roman Lysak <lysak at fzu.cz> wrote:
>>   Hi Ulla,
>>
>>
>>
>> On 09/12/2013 06:51 PM, Ulla Blumenschein wrote:
>>> Hi Roman,
>>>
>>> Could you explain how we define Born and dressed in a generator
>>> independent way in Rivet?
>>
>> it depends on the object type.
>> For example, for Z boson (similarly for W boson), you can specify whether to
>> add photons (next to last one parameter in the constructor below) in a given
>> radius (2nd next to last one parameter) around the leptons from Z decay to
>> the Z boson 4-momentum.
>>
>>        //fiducial phase space + born level
>>        ZFinder zfinder_mu(-2.4, 2.4, 20, MUON, 66.0*GeV, 116.0*GeV, 0.1,
>> false, false);
>>        addProjection(zfinder_mu, "ZFinder_mu");
>>
>>        //for combined cross-sections (combined phase space + dressed level)
>>        ZFinder zfinder_comb_mu(-2.5, 2.5, 20, MUON, 66.0*GeV, 116.0*GeV, 0.1,
>> true, false);
>>
>>
>> Sorry for late response.
>>
>> Cheers,
>>    Roman
>>
>>
>>
>>> Cheers, Ulla
>>>
>>> /_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
>>>       Ulla Blumenschein
>>>       II Physik, Uni Goettingen
>>>       Friedrich-Hund-Platz 1, D01.110
>>>       phone: 0049-551-397645
>>> /_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
>>
>
>