Serious Issues With Simulated Zmass

Basically I am doing a study of the ECAL for my 3rd year project. This project is sooo hard, I’ve come this far but I really want a top grade for it.

I’m looking at the Zmass resolution. I have noticed that Endcap electrons passing through the Preshowers may have weird inter-calibration with their Preshower and Electron energies. This could be affecting the Zmass resolution (not such a narrow peak around 90GeV).

So I have found a fraction of energy that the preshower constitutes the electron energy. It was also a gaussian with a deviation, so I can get various values of preshower constant from it.

I want to simulate a Zmass gaussian distribution and vary it using the preshower calibration constant (its a simple factor) to see whether the resolution around 90GeV improves or not.

How do I go about doing this?

I was thinking I would use a Zmass of 90Gev and have 1000 ways in which a pair of electron could decay from it. So I have a bunch of numbers, how do I fit this into a gaussian curve and vary it using my preshower constant?

Below is my zmass using real data from CERN. Now I want to simulate my own Zmass distribution. How?