B Are quarks fundamental elements of matter?

[nauq]

I would like to ask scientists or anybody: what do you think about qwarks, do you consider them to be the littiest parts of matter or that matter is cyclically or infinitaly smalling, like numbers, or that there are some smaller parts, which have not been observed, but they have an end in their smallness? What do you think we should do (maybe with qwarks) or what are you doing to find fundaments of matter?

 

[Nugatory]

According to our best theories so far, quarks are elementary particles not composed of anything smaller.

We can speculate that there's more going on than that, but with neither experimental evidence nor any convincing alternative theories this speculation is sterile.

 

[DennisN]

what do you think about qwarks, do you consider them to be the littiest parts of matter

According to our best theories so far, quarks are elementary particles not composed of anything smaller.

@nauq: And the case is the same for electrons (and they are not composed of quarks).

 

[ohwilleke]

The Standard Model has six kinds of quarks (in three colors each and two parities each), eight color charge combinations of gluons, three kinds of charged leptons (electrons and two kinds of heavy electrons that are also identical), three kinds of neutrinos, three kinds of particles related to the weak force, photons, and the Higgs boson.

Electroweak theory in the Standard Model, moreover proceeds from a frame in which there were different (although not smaller or more rare) kinds of fundamental force carrying particles that mixed with each other in a particular way to produce the force carrying particles that we see now related to the weak force and electromagnetic force.

In the Standard Model, these particles have properties like electromagnetic charge, color charge, mass-energy, baryon number minus lepton number, Lorentz invariance, and other more obscure properties that are conserved in all interactions of all kinds of particles, which suggest that these are not just random interchangeable parts.

Also, thinking of these particles as just different kinds of legos also oversimplifies the situation, although usefully in many cases. The world is quantum mechanical. This means all particles have probabilistic behavior and in some applications are better thought of as acting like waves spread over a volume of space-time rather than simply physical point particles. In effective field theory descriptions of fundamental physics, these particles are really just a fine and discrete set of ways that fields in the theory can be excited which is rather less particle-like that a simple understanding from some educated layman explanations of what is going on according to science would suggest.

There is currently no solid evidence that any other particles are required to describe particle physics (although there might be a graviton associated with transmitting gravity and there might be one or more particles associated with dark matter and dark energy phenomena).

If there are more fundamental particles that can produce exactly this set of particles in an emergent way, that's cool, but we don't need them to do anything we currently know about fundamental physics. We certainly don't have any positive evidence that there is something more basis than the many different kinds of fundamental particles of the Standard Model, and not for want of trying by many very smart scientists. But that doesn't preclude the possibility that something will be discovered in future that is deeper in some sense that our functional but ugly Standard Model plus General Relativity understanding of the Universe.

 

[physika]

I would like to ask scientists or anybody: what do you think about qwarks, do you consider them to be the littiest parts of matter or that matter is cyclically or infinitaly smalling, like numbers, or that there are some smaller parts, which have not been observed, but they have an end in their smallness? What do you think we should do (maybe with qwarks) or what are you doing to find fundaments of matter?

There are preon models but that faded with time. supposedly the preons would constitute the quarks.

On the Preon Model.
https://www.scirp.org/journal/paperinformation.aspx?paperid=92427

A Schematic Model of Quarks and Leptons. Physics Letters B, 86, 83-86.
https://doi.org/10.1016/0370-2693(79)90626-9

 

[Fractal matter]

I would like to ask scientists or anybody: what do you think about qwarks, do you consider them to be the littiest parts of matter or that matter is cyclically or infinitaly smalling, like numbers, or that there are some smaller parts, which have not been observed, but they have an end in their smallness? What do you think we should do (maybe with qwarks) or what are you doing to find fundaments of matter?

It is unknown whether quarks have a substructure. I, personally, believe there are no fundamental particles at all(all are quasiparticles). It looks likely quarks are made of subquark triplets, on the manner quarks are triplets. There is a book describing that(and much more), though it's highly speculative. Subquarks were described as fundamental(in a certain sense) in it.

 

[ohwilleke]

Sabine Hoffenfelder has a nice new blog post on why fundamental Standard Model particles aren't composite particles of the things that they decay into, which, while not fully rigorous (the language in bold, for example, is model dependent), gets across the concept pretty well.

Read the whole thing, which isn't very long, but the key concept is as follows:

Let’s take for example the tau. The tau is very similar to the electron, except it’s heavier by about a factor 4000. It’s unstable and has a lifetime of only three times ten to the minus thirteen seconds. It then decays, for example into an electron, a tau-neutrino and an electron anti-neutrino. So is the tau maybe just made up of those three particles. And when it decays they just fly apart?

But no, the tau isn’t made up of anything, at least not according to all the observations that we currently have. There are several reasons physicists know this.

First, if the tau was made up of those other particles, you’d have to find a way to hold them together. This would require a new force. But we have no evidence for such a force. . . .

Second, even if you’d come up with a new force, that wouldn’t help you because the tau can decay in many different ways. Instead of decaying into an electron, a tau-neutrino and an electron anti-neutrino, it could for example decay into a muon, a tau-neutrino and a muon anti-neutrino. Or it could decay into a tau-neutrino and a pion. The pion is made up of two quarks. Or it could decay into a tau-neutrino and a rho. The rho is also made up of two quarks, but different ones than the pion. And there are many other possible decay channels for the tau.

So if you’d want the tau to be made up of the particles it decays into, at the very least there’d have to be different tau particles, depending on what they’re made up of. But we know that that this can’t be. The taus are exactly identical. We know this because if they weren’t, they’d themselves be produced in larger numbers in particle collisions than we observe. The idea that there are different versions of taus is therefore just incompatible with observation. . . .

A decay is really just a type of interaction. This also means that all these decays in principle can happen in different orders. Let’s stick with the tau because you’ve already made friends with it. That the tau can decay into the two neutrinos and an electron just means that those four particles interact. They actually interact through another particle, with is one of the vector bosons of the weak interaction. But this isn’t so important. Important is that this interaction could happen in other orders. If an electron with high enough energy runs into a tau neutrino, that could for example produce a tau and an electron neutrino. In that case what would you think any of those particles are “made of”? This idea just doesn’t make any sense if you look at all the processes that we know of that taus are involved in.

Everything that I just told you about the tau works similarly for all of the other unstable particles in the standard model. So the brief answer to the question why elementary particles can decay is that decay doesn’t mean the decay products must’ve been in the original particle. A decay’s just a particular type of interaction. And we’ve no observations that’d indicate elementary particles are made up of something else; they have no substructure. That’s why we call them elementary.