See also

https://lhcb-public.web.cern.ch/Welcome.html#ccus

https://cerncourier.com/a/lhcb-observes-four-new-tetraquarks...

https://arxiv.org/abs/2103.01803

Thanks, those are really informative.

Anyone know what the typical lag is between measurement and discovery for these kind of experiments? From reading between the lines, it seems to me that this discovery is based on re-analysis of the 2016 measurement data, but they don't mention the dates when the data was collected. I had expected the turnaround time to be in the order of months rather than years, e.g. 6-9 months to analyze experimental data, 6 months to prepare for publication, so let's say 1.5 years between experiment and claimed discovery. But this may be hopelessly naive, I don't have any comparable experience to rely on.

Also, what's the typical lifetime of these tetraquarks? None of these configurations are stable, so is it even accurate to call them "particles"?

> None of these configurations are stable, so is it even accurate to call them "particles"?

Not really, not when they're this unstable. Traditionally hadrons that decay very quickly are called "resonances" instead.

The dividing line between a particle and a resonance is usually whether you quote its lifetime in seconds or MeV :) The two are directly related through the uncertainty relation, specifically the one coming from the energy-time commutator.

The found some more tetraquarks. Saved you some times since the article takes way way way too long to say that.

Yeah, don't know much more about them than that. The post is a pretty short breakdown of the Standard Model and LHC's contribution to it.

I don't know much about the topic, but I wonder if particles could hypothetically break down to infinity. Can someone comment?

The Earth is not large enough to build a particle collider big enough to test if String Theory describes the most elemental particles or if there is something smaller. We might be only a handful of generations of particle accelerators until spaced based colliders. All of this is to say, you’re going to need to be okay with you personally never knowing this answer. It’s all theoretical.

I cannot comprehend what would be inside a particle that would be a smallest possible one. Division to infinity feels calming.

These particles don't have a volume; they're point-like. They don't exactly have an inside with other particles waiting to burst out. These are just mathematical abstractions after all, good at making some predictions. May or may not be actual reality.

But when I picture a point, I can see it and since it has a visible area, then what's in it? That's my problem. I could picture it as nothing maybe? But then what's in the blank space? It has a volume...

Probably because we learn about points by drawing them on a graph at some point in math class, so we imagine them having an area. I think points are an abstract construct. Sort of like infinity - you can never truly reach it. Or imagine it.

That's more an issue with your mental model. These aren't points, they are fields with potentials.

Seems to me that the way the universe prevents naked quarks from existing blocks particles from getting any smaller.