The aim of this blog is to demonstrate that in order to compare physical quantities like pseudo-rapidity and track quality parameters like the number of hits used to build the track (NHit) one has to impose conditions on the multiplicity of the events.

For this particular request we are embedding low momentum pions from decaying rho mesons generated by StarLight into zero bias data events.

The comparison to data is done with min bias events (vpd_mb)

The "centrality" of the event is defined as fractions of the RefMult distribution in the min bias events:

The centrality of the event is defined at the following values of refmult

0%    600

20%  400

40%  254

60%  115

80%    29

The distribution of multiplicities in the embedded sample is much more peaked at small number of tracks:

As can be seen in the multiplicity plot shown above, our embedded sample is still small (10 FSETs generated so far) but the comparisons MC and minbias data as encouraging.

We show below the pseudo-rapidity and the NHit comparisons:

At 40-60%

Finally our most central bin; 20-40%

The number of events that we have generated so far is small but the trend is becoming visible. We will then proceed with the generation of more FSETs and this blog will be updated as more data becomes available.

The complete QA files have been attached to this blog.