## LHC Higgs animations

When a Higgs (or Higgs-like particle) is formed at the LHC it immediately decays, but the particles it decays to can be predicted by theory. The two main experiments, ATLAS and CMS, are designed to look for some of these specific decay channels, two important modes of which are the Higgs decaying to two photons, $\displaystyle H \rightarrow \gamma \gamma$, and to four leptons via Z bosons, $\displaystyle H \rightarrow ZZ \rightarrow 4 \ell$. The problem is that other collisions and decays make these same particles as well, so there’s an ever-present background that the signal needs to be divorced from. To extract the signal you need to perform many, many collisions and apply advanced statistical techniques.

That’s all great, but what the two experiments recently did that I think is very cool is made time-varying animated GIFs of the data collected in these two channels. The x-axis shows the energy is units of giga-electronvolts or GeV, and since they’re histograms the y-axis shows events per certain GeV bin.

First off is the $\displaystyle H \rightarrow ZZ \rightarrow 4 \ell$ from ATLAS:

And then a different form of graph for ATLAS’s $\displaystyle H \rightarrow \gamma \gamma$ channel:

And finally, from CMS, another $\displaystyle H \rightarrow ZZ \rightarrow 4 \ell$ channel:

If a GIF has finished animating, you can just refresh the page to start it again.