Difference between quarks & protons

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Discussion Overview

The discussion centers on the differences between quarks and protons, specifically exploring the intrinsic properties of each and whether there are characteristics unique to one that are not present in the other. Participants delve into theoretical aspects, properties related to quantum numbers, and the philosophical implications of defining wholes versus parts in particle physics.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant questions whether there are properties that quarks possess that protons do not, and vice versa, emphasizing the need for a distinction beyond quantitative measures like mass, charge, and spin.
  • Another participant notes that quarks are elementary particles with color charge, which does not apply to protons, suggesting a fundamental difference in their properties.
  • Some participants argue that the traditional view of three quarks forming a proton is overly simplistic and that a deeper understanding requires modern perspectives such as those from Deep Inelastic Scattering.
  • A participant expresses curiosity about whether the whole (proton) has unique properties that cannot be fully explained by its constituent parts (quarks), raising philosophical questions about the nature of wholes in physics.
  • There is a mention of color charge as a property that does not add like ordinary numbers, indicating a different mathematical treatment for quarks compared to protons.
  • One participant draws an analogy between the relationship of quarks to protons and the relationship of bricks to a house, questioning the sufficiency of component properties to define the whole.
  • Another participant introduces the idea that electrons do not contain quarks, prompting further questions about the nature of charge and flavors in elementary particles.

Areas of Agreement / Disagreement

Participants express a range of views on the properties of quarks and protons, with no consensus reached on whether there are unique characteristics at either level. The discussion remains unresolved regarding the sufficiency of component properties to define the whole.

Contextual Notes

Some participants acknowledge the limitations of their understanding and the complexity of the subject, indicating that the discussion may not cover all fundamental details or nuances in particle physics.

werunom
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Hello.

One basic question.
What properites that quarks have which their "compound" forms [protons/neutrons] don't have and vice-versa? That is, a proton may have some property or characteristic and the quarks might not be having that. So something which is NOT available at the components level is present at the 'whole' level [or vice-versa].
Are they any properties/characteristics like that?

The intrinsic properties of quarks are [from wikipedia] - spin, mass, electric charge & colour charge.
Now, 3 quarks form a proton. And the intrinsic properties of a nucleon - spin, mass & electric charge.

Mass, spin & charge are quantitative. they add up or get subtracted. So the 'whole' formed [proton/neutron] would have the property which is sum of the components' properties. And other numbers like - baryon no., charm, etc. - are again quantitative.
Colour charge is of course not available at the nucleon level because of they are used to explain the strong force - which forms the 'whole' itself.

So is there any specific characteristic/property that is present at one level [individual or whole level] but not at other?

NB - When I say characteristic/property, I am not referring to the behaviour of the referred object. the behaviour, say deflection in a magnetic field, is because of a property like charge. Going by this, there are many behavioural differences between a nucleon and a quark. So, it is not this that I am asking.

Thanks.
 
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Quarks are elementary "pointlike" particles
Quarks are in the color-triples rep.of SU(3), whereas all "physical" states like protons must be color-singuletts (color-neutrality)

It is not true that "three quarks form a proton"; this is a simplified picture from the old-fashioned quark model. For a modern perspectice how a proton (or a QCD bound state in general) looks like you should study e.g. Deep Inelastic Scattering and especially Nucleon Structure Functions.
 
First of all, thanks for replying.

When we consider color charge property, there is of course difference. But what I am interested in is the difference between these two at the intrinsic properties that define each of them.

So can I say that there is no single basic property [at least that what we are aware of] which one has [either proton or quark] and the other doesn't? Because of all what we know, except colour property, everything is just quantitative summing up [charge, mass, spin].

Is there any other property, at each level, that we need to know to define it and it's state other than - charge, mass, spin & colour charge[only in case of quark]?
 
What else? Why shouldn't all these properties and quantum numbers not be enough?

I mean algebraically (naively) protons are made of exactly three quarks coupled together to a spin and isospin doublet, color singulet, ...; what is missing?
 


That's why I am writing "algebraically" and "naively". W.r.t. to the algebraic properties like spin, isospin and color this naive picture is correct.
 
@tom.stoer - Thanks for confirming that.

I asked this question with a particular philosophical curiosity. If the whole [e.g. proton] doesn't have anything of its own and can be explained by and in terms of the parts [quarks], then is there any whole?

I didnt put the question with philosophical undertones as it is not a forum for one.

So, physically speaking, if there is any difference between the proton [whole] and the parts [quarks], let me know.
[As I have already said - I am asking properties which define their nature and behavior.]

Thanks.
 
Color.
 
@Dickfore
yah... colour has been discussed above, in the initial posts.
 
cool. Bear in mind that color does not add like ordinary numbers. This does not mean it is not a quantitative measure of the intrinsic properties of the quark. It simply means it obeys different rules of mathematics. I don't know them exactly at this point, because I am not very versatile in Representation Theory of Lie groups and algebras.
 
  • #10
Thanks for adding that info.
 
  • #11
What is the difference between a house and the bricks?
 
  • #12
tom.stoer said:
Quarks are elementary "pointlike" particles
Quarks are in the color-triples rep.of SU(3), whereas all "physical" states like protons must be color-singuletts (color-neutrality)

It is not true that "three quarks form a proton"; this is a simplified picture from the old-fashioned quark model. For a modern perspectice how a proton (or a QCD bound state in general) looks like you should study e.g. Deep Inelastic Scattering and especially Nucleon Structure Functions.



are there quarks in electron?
if not then what give electron charge and it's flavours?
 
  • #13
what is weak interaction and forces?
how do they transform and what's their role?
 
  • #14
There are no quarks in the electron (but strictly speaking there are higher-order processes in which an electron has some sort of "quark-content" - but this is certainly confusing in this context).

What is the purpose of this thread?
 
  • #15
"What is the difference between a house and the bricks?"
Who said there is?!

And that is what I am trying figure out. But didn't want commit a mistake because of the shallow knowledge about quantum physics.

The purpose of the thread is to clarify/debate whether the components and their properties are sufficient and the notion of whole can be overlooked.
E.g. consider a normal atom's nucleus. The so called whole proton is never a singular whole. It would have been valid to call the group of three quarks forming proton as a whole, if, after the formation, the other neighbouring particles or groups interact with this whole singularly. But that is not the case - the quarks that comprise the so called whole are independently interacting with other particles; each of the particles, irrespective of the whole they form, are independently interacting with other neighboring particles.
Isn't it the same "thought-flow" about the electrons shared between atoms forming a molecule?
[In fact ... you can see a futile attempt https://www.physicsforums.com/showthread.php?t=460327"to discuss a similar topic]

Other than this, nitin_zilch may have purpose of his own :).

PS -
I do understand that, by now, the pedantic [with no irony/sarcasm intended] physicists would be irritated for all the specific things and fundamental details that i have overlooked or how smoothly & naively I have laid out the "interactions" and the concept of proton/quark. Kindly excuse for that.
If you guys have anything to contribute to this thought-flow, please feel free.
 
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