Some other important details about Zee Reconstruction

Continuing the investigation on the Zee problem, we start to look at the tracks formed by the Zee events. We remember that now the Tracks software being used is now Trk::Tracks and the end of the Tracks is now being studied by ExtrapolatorToCalo.

You may want to explore the efficiencies of these tracks and the Pt recovery of the tracking reconstruction algorithm. For that, please, look at these web pages.

For the tracks, we first investigate the tracks multiplicity :

Also, we first investigate the tracks multiplicity for different Pt cuts (2 GeV, 5 GeV, 10 GeV) :

Tracks Chi Square :

Tracks Z0 :

Tracks Impact parameters (The tracks with abs(Impact) greater than 35 have abs(Vertex Eta) greater than 2) :

Tracks Z0 versus Impact parameter (Is that the beam spot?!):

For the tracks we can see now the Pt curve from 0 to 10 GeV. This can be compared with the :

As can be seen, the exponencial decay value is very similar, but the constant is a lot bigger in the truth case. For the reconstructed tracks, the initial value is where higher inefficiencies can be found.

Also, we can compare the profile at very low Pt. As one can see, the peak found at the truth analysis is moved to higher Pt than the peak found at the Stable Charged Particles distribution. This can be understood looking at the reconstruction efficiency :

Their Eta distribution of the tracks (weirdly peaking at eta=2.5) :

An uniform Phi distribution (as expected) :

Also, we investigate the Eta difference distribution for the beginning of the track (Vertex) and at the extrapolated, by the ExtrapolatorTool tool, position at the EM calorimeter entrance.

Since the magnetic field is in the beam direction there is no distortion in the Eta direction for the beam. However, when looking at the Phi direction, the displacement is clearly influenced by the charge and the momentum of the particle :

Of course, this displacement has a strong correlation with the momentum. In the next plot, we have Delta Phi correlated with momentum :

One can see the bending related to the Pt of the track, as it should be expected but just to some of the higher Pt tracks.

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