>The dynamics of quarks and gluons can be described perturbatively in hard processes thanks to the smallness of the strong coupling constant at short distances, but the spectrum of stable hadrons is affected by non-perturbative effects and cannot be computed from the fundamental theory. Though lattice QCD attempts this by discretising space–time in a cubic lattice, the results are time consuming and limited in precision by computational power. Predictions rely on approximate analytical methods such as effective field theories.

I'm glad this was mentioned, non-perturbative effects are not well understood and this is a big part of why it's worthwhile to study bound states of the strong force.

Are there a lot of missing overbars in this article, or some other typographic marker for antiquarks? I assume the hexaquark descriptions early on are supposed to be (using Q for q-overbar) "QQQqqq or qqqqqq", where it reads to me as "qqqqqq or qqqqqq".

I really read this title wrong

As I wrote somewhere else, I rather like the cuddly hadrons from The Particle Zoo: https://www.particlezoo.net/collections/particle-packs

Whenever I come across such news, it seems like we are still far from grasping the complete picture. It's akin to gazing at the sky without a telescope and assuming we have seen all the stars in the universe.

I speculate that in the coming decades or centuries, a new instrument may enable us to delve deeper into the atom and reveal that what we perceive now is merely a minuscule fraction of the whole picture.

Perhaps the notion that the subatomic world is as vast as the universe, as stated by Richard Feynman when he said "There’s plenty of room at the bottom.", holds more truth than we realize.

"also implies the existence of a Tbb state, with a bbud quark content, that should be stable except with regard to weak decays"

Can someone explain this to me?

Tcc(3875)+ can decay to a D0 and a D+, yes? And this is a strong decay?

I guess the reason Tbb doesn't have an equivalent strong decay to B mesons because of the sign difference -- that is, B0 and B+ would have anti-bs, not bs; and anti-B0 and anti-B+ would have negative charge?

And so the only major decay pathway is for the b itself to decay to a K+ (plus lepton noise), giving a temporary bu\s\u\d pentaquark, that then has uninhibited decays?

I guess what I'm asking is... is this the right way to think about this?

gratuitously suggestive title is gratuitous. :P

Can anyone recommend a book or other resource for a lay person to understand this?

Since the way we find these is to smash the larger atomic constructs with (relatively) huge amounts of energy I do wonder how much we can know of their ground state, motion & behaviour absent those forces.

Do we have anomalies accumulating here that indicate the early phase of a scientific revolution in Thomas Kuhn's terminology, that is, a replacement of the standard model/QCD? Or is it still "so far, so good"?

> The challenge of understanding how quarks are bound inside exotic hadrons is the greatest outstanding question in hadron spectroscopy.

They must be more like knots: https://en.wikipedia.org/wiki/Knot_(mathematics)

Quarks are small masses, gluons are strings connecting them, and the whole thing is in a rapid periodic motion.

> Like Mendeleev and Gell-Mann, we are at the beginning of a new field, in the taxonomy stage, discovering, studying and classifying exotic hadrons.

The chemistry of matter that's smaller than protons and larger than electrons is indeed a missing piece. But the real breakthru will be discovering a membrane that's impenetrable to those multiquarks.

I shouldn’t have skimmed the tittle

Now that's a headline that you don't want to type wrong.

“All science is either physics or stamp collecting.” -Ernest Rutherford

Is this stamp collecting? Do these exotic hadrons mean anything?

My dyslexic brain: "Exotic whatnow?"

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