But before we can understand the bad news, it’s best to start with the good news.
The Good: Standard Model Glory
On its ongoing mission to explore the most primordial of matter of the Universe, the LHC slams particles (usually protons, sometimes higher-mass hadrons like lead nuclei) together at close to the speed of light. By doing this, for the briefest of moments, the energy conditions that existed shortly after the Big Bang are created. From this energetic soup, particles that were last seen buzzing around the ancient universe some 13.75 billion years ago condense from the blast of energy, like raindrops condensing inside a raincloud.
By their nature, these newly-condensed particles buzzing inside the LHC’s monstrous detectors are unstable, so they quickly decay into other particles. These decays are extremely important to physics as they provide a very privileged view into how particle interactions worked during the earliest moments of the universe and bolster decades of scientific theory.