Higgs boson re-discovery from a CERN dataset (for a project)

[omerel]

Homework Statement

Seminar Project

Relevant Equations

H -> ZZ -> 4l (muons)

Hi everyone!
I'm working on a seminar project on elementary particles, and I'm supposed to introduce the LHC and rediscover the Higgs boson from a dataset I got from CERN open source.
I don't understand how am I supposed to discover the gap (in the invariant mass diagram) around the Higgs boson mass (125 GeV).
I've watched CERN's official video on the Higgs discovery (Higgs boson decay to two photons), and several code implementations relevant to my problem (H->ZZ->4l) and couldn't understand the idea of how you actually see the gap around 125 GeV?
When I plot the histogram of Z boson invariant masses, I do not see anything unusual.
For your convenience, I attached two of my histograms- one for Z boson pairs invariant mass (i.e came from the same decay) and the second is the invariant mass of a single Z boson invariant mass. The invariant mass is in GeV units.

 

[Vanadium 50]

What is this gap you are talking about?

What is the dataset you are looking at? Is it big enough to see the Higgs? The Z peak seems awfully small.

 

[malawi_glenn]

Can you provide more information on how you analyzed the data? E.g. cuts used and so on. Also provide a link to the dataset

One Z is off shell so you can not write "invariant mass of two Z" here