[Rivet] Tau decays from Particle guns

[Holger Schulz]

Hi again,

I narrowed it down to the UnstableFinalState Projection,
source code, line 34:

    !isZero(p->momentum().perp())

If a gun produces tau decays, the taus are produced at rest, resulting 
in them being
rejected from the accepted particles.

Any ideas how to cope with this? Simply dropping the cut on the 
transverse momentum
makes my code work as expected but I have no feeling what it would break 
in other cases.

Alternatively, I could put some reconstruction code in the taufinder.

Holger




On 02/08/14 22:16, Holger Schulz wrote:
> Hi,
>
> I am doing some tau stuff and came across a problem I do not know how 
> to tackle.
>
> When I look for taus coming from, e.g. an electron-positron collision, 
> everything is fine.
> However, when trying to do the same with a tau-gun, the taus 
> themselves are
> to be found in the incoming particles of a vertex and the TauFinder is 
> unable to find
> them. Can someone with some more experience with HepMC give me some 
> pointers
> how to do this properly? It might also be a generator issue (Sherpa in 
> DECAYER mode).
>
> Thanks,
> Holger
>
>     GenEvent: #1 ID=0 SignalProcessGenVertex BarcodisZero(e: 0
>      Momenutm units:     GEV     Position units:      MM
>      Cross Section: 0 +/- 0
>      Entries this event: 2 vertices, 5 particles.
>      Beam Particles are not defined.
>      RndmState(0)=
>      Wgts(1)=(0,1)
>      EventScale -1 [energy]      alphaQCD=-1     alphaQED=-1
>                                         GenParticle Legend
>             Barcode   PDG ID      ( Px,       Py,       Pz,     E )
>     Stat  DecayVtx
>     ________________________________________________________________________________
>     GenVertex:       -1 ID:    6 (X,cT):0
>      Wgts(1)=1
>      I: 1     10001       15 +0.00e+00,+0.00e+00,+0.00e+00,+1.78e+00  
>     2        -1
>      O: 1     10002       15 +0.00e+00,+0.00e+00,+0.00e+00,+1.78e+00  
>     2        -2
>     Vertex:       -2 ID:    6
>     (X,cT)=+0.00e+00,+0.00e+00,+0.00e+00,+8.17e-02
>      Wgts(1)=1
>      I: 1     10002       15 +0.00e+00,+0.00e+00,+0.00e+00,+1.78e+00  
>     2        -2
>      O: 3     10003     -211 -4.88e-01,+1.27e-01,-1.85e-01,+5.55e-01   1
>               10004      130 +1.86e-02,+3.71e-02,-2.53e-01,+5.60e-01   1
>               10005       16 +4.69e-01,-1.64e-01,+4.38e-01,+6.62e-01   1
>
>
>
>
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