[NovaS1X]

This is a great answer. Thank you.

So in these situations how do you tell apart electrons from one source compared to another? In the article they mention how the LHC collides particles at a rate of "40 million times each second". I can imagine there are a lot of electrons and other particles flying around from other collisions. What makes an electron discernible between one type of particle and another?

[frob]

Truly, you never really know which pair of particles came from a specific decay, and which come from some other processes and just happen to line up with the mass/energy you're looking at. Fortunately, for most particles, the combinatorial background signal follows a smooth curve around the energies you're looking at, so you can fit a curve to that background signal and then attribute the rest of the signal to the particle production. For an example, see the main plot on the Upsilon page in Wikipedia (https://en.wikipedia.org/wiki/Upsilon_meson). You can see there is a linear decline (in log space) of the background signal but then there's another peak around 9.5 GeV which is the additional signal from the Upsilon decay.

The point is, we cannot tell which pair of electrons/muons come from the decay of a specific particle, but we can tell how many extra occurred beyond what we would expect from all other known processes.

[NovaS1X]

Thanks so much for the explanation and the example. I at least know a little more about these complicated endeavours now.

[frob]

Happy to do it! Thanks for asking insightful questions. :)

[retbull]

Statistics like the op said. If you are expecting your decay products from an interaction to be 20% X and 80% Y but after 100 billion attempts which should have averaged out to the expected outcome you instead get 21% X and 79% Y something in your calculation is wrong.