Eli5: It was posted in the science page that experiments at the Large Hadron Collider (LHC) have yielded the simultaneous appearance of three force-carrying elementary particles that had never been seen together before.

Question

Can anyone help me understand what this means and how important this discovery is?

In: Physics

Answer 1

The LHC collides protons with a very high energy with each other. The collisions produce many new particles, including very short-living particles that you can’t study elsewhere. What happens in each collision is random and some processes are very rare so we need many collisions to study them.

Based on known physics, we can predict how often the different outcomes should happen. But maybe there are new interactions that we don’t know about yet. The best place to search for them are reactions that are predicted to be very rare: Finding a needle in a haystack is easier if that haystack is smaller. Producing two specific short-living heavy particles plus an extra photon is one of these extremely rare events – expected to happen only once per 20 trillion collisions. One of the LHC experiments found collisions with that outcome, and the measured rate agrees with predictions.

It’s the expected outcome, so it’s not that significant on its own. It’s another place where we now know there is no new physics happening.