[Rivet] Z boson mass taken from ZFinder is pre-FSR or post-FSR

[Yu-hsiang Chang 張祐祥]

Ok, thank Deepak and Andy.
Yu-hsiang 


     Andy Buckley <andy.buckley at cern.ch> 於 2015/6/16 (週二) 6:16 PM 寫道﹕
   

 By default, photons from hadron decays (no matter how indirect) are
excluded.

Andy


On 16/06/15 11:03, Yu-hsiang Chang 張祐祥 wrote:
> Hi All,
> 
> I have another question. When ZFinder want to include the photons'
> energy and momentum (photon within the cone size that you set) to
> leptons, does it consider the particle ID and particle's mother ID since
> I don't want to include the photon which comes from Pion or other hadrons.
> 
> Yu-hsiang 
> 
> 
> 
> 
> Yu-hsiang Chang 張祐祥 <index0192 at yahoo.com.tw> 於 2015/6/11 (週四) 4:51
> PM 寫道﹕
> 
> 
> Dear Frank,
> 
> After I set the cone size of ZFinder = 0.0
> 
>        const ZFinder zfe(fs, -2.5, 2.5, 0*GeV, PID::ELECTRON, 15*GeV,
> 1500*GeV, 0.0 );
> 
> I see my rivet result(red) is consistent with the post-FSR result(blue).
> 
> Now I am asking the author their cone size for pre-FSR.
> 
> Thanks.
> 
> Yu-hsiang
> 
> 
> 
>  
> 
> 
> 
> 
> 
> 
> Frank Siegert <frank.siegert at cern.ch> 於 2015/6/9 (週二) 7:03 PM 寫道﹕
> 
> 
> Hi Yu-hsiang,
> 
> the ZFinder object will (by default) use "dressed" leptons, which
> means that photon radiation within a cone of dR=0.1 is included. This
> is a generator independent and less QED-FSR-dependent definition,
> which is neither pre-FSR (often called "Born" level leptons) nor
> post-FSR (often called "bare" leptons). It does sum parts of the FSR
> but not all of it (namely not the wide angle emissions). If you want
> to use "bare" leptons for your comparison you would have to set dR=0.0
> in the ZFinder constructor.
> 
> If on the other hand you are writing a Rivet plugin for an actual
> experimental measurement the question is what is the truth level to
> which your analysis has been unfolded ("dressed", "Born" or "bare")?
> 
> Cheers,
> Frank
> 
> 
> On 9 June 2015 at 12:14, Yu-hsiang Chang 張祐祥 <index0192 at yahoo.com.tw
> <mailto:index0192 at yahoo.com.tw>> wrote:
>> Hi all,
>>
>> I have question for the FinalState and the ZFinder in Rivet.
>>
>> I want to know when I take the Z boson mass from the ZFinder, it is
> pre-FSR
>> or post-FSR? (undergoes final state radiation(FSR) or not. In other words,
>> does the 4-momentum of Z boson includes the energy and momentum of the FSR
>> photon? )
>>
>> For example, my Rivet plugin SMP_13_003.cc has these content :
>>
>> ---------------------------------------------------
>>    void init() {
>>
>>      // Full final state
>>        const FinalState fs(-5.0, 5.0);
>>        addProjection(fs, "FS");
>>
>>        // Z finders for muons
>>        const ZFinder zfe(fs, -2.5, 2.5, 0*GeV, PID::ELECTRON, 15*GeV,
>> 1500*GeV);
>>        addProjection(zfe, "ZFE");
>>
>> ......
>>    }
>>
>>
>>    void analyze(const Event& event) {
>>
>>      const ParticleVector& z = zfe.bosons();
>>      const double mass_z = z[0].mass();
>>
>> ......
>>    }
>> ---------------------------------------------------
>>
>> So I want to know the mass taken from the Z boson is pre-FSR or post-FSR?
>>
>> Since I use the result of my rivet plugin (from YODA and then transform it
>> to ROOT format),
>> to compare with the pre-FSR and post-FSR mass of Z boson (generated by
>> Powheg),
>> and I find my rivet result is consistent to the pre-FSR instead of
> post-FSR.
>> (previous one tell me that the FinalState object has already undergone the
>> FSR,
>> but since now I see inconsistent so I want to ask the part of ZFinder)
>>
>> I put my rivet plugin (SMP_13_003.cc), and the comparison (snap shot ) in
>> attachment.
>> In comparison, the red point is the result of my rivet plugin, and the
> blue
>> line is the pre-FSR or post-FSR.
>>
>> Thanks.
>>
>> Yu-hsiang
> 
>>
>>
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> 
> 
> 
> 
> 
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-- 
Dr Andy Buckley, Lecturer / Royal Society University Research Fellow
Particle Physics Expt Group, University of Glasgow


  
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