The Quark Thread: Answers to Questions

[Mk]

The "Quark" thread

The "Quark" thread seemed to have been indiscriminately locked (I appreciate a last post to say why). I still have question about quarks. From what marlon and arivero said, it sounds like quarks have not been "seen." Is this so?

Why does the color force and strong force increase in strength at a distance? This seems to be the opposite of common sense, but its quantum physics.

 

[Mattara]

Here are some links that might be of value for you in this particular phenomena.

http://hyperphysics.phy-astr.gsu.edu/hbase/particles/quark.html#c6
http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/scatele.html#c1

 

[Meir Achuz]

The "Quark" thread seemed to have been indiscriminately locked (I appreciate a last post to say why). I still have question about quarks. From what marlon and arivero said, it sounds like quarks have not been "seen." Is this so?

QUOTE]
That depends on what is meant by "seen". You have seen lions by shining light into their cage and looking at how it bounces off the lion. I have never touched a lion, although my friend Lefty did.
In the same way, quarks have been seen by sending photons into a proton and looking at how they bounce off the quarks inside. Not even Lefty has touched a quark though.

 

[Meir Achuz]

Why does the color force and strong force increase in strength at a distance? This seems to be the opposite of common sense, but its quantum physics.

Almost the earliest force you played with as a child increased with strength at a distance. (Think rubber band.)

 

[arivero]

Why does the color force and strong force increase in strength at a distance? This seems to be the opposite of common sense, but its quantum physics.

Well, they do not increase, they just do not decrease.

For a constante force the energy increases, because it is force times lenght.

the difference between electricity and colour is that force carriers (the gluons) are charged themselves, while photons are neutral.

 

[Gokul43201]

Why does the color force and strong force increase in strength at a distance? This seems to be the opposite of common sense, but its quantum physics.

[being a little glib]Does the restoring force of a spring seem counterintuitive too ?

 

[pallidin]

Well, I could be wrong here, but I thought I heard somewhere that it DOES increase with distance due to interaction with the virtual particles in vacuum space(not talking about rubber bands or springs here, of course!)

 

[arivero]

To be honest, QCD as a problem of eigenstates is not solved yet. So people uses models (or approximations) where the potential increases or models where the force increases, but just the former (the increasing of potential) is enough to get models of confinement.

 

[Meir Achuz]

Well, I could be wrong here, but I thought I heard somewhere that it DOES increase with distance due to interaction with the virtual particles in vacuum space(not talking about rubber bands or springs here, of course!)

I think this is a minor confusion of language between you and arrivero.
The belief is that long distance q-q force is constant.
This corresponds to a linear increase in the potential energy.
The force is confining, like a spring or rubber band, but does not have a quadratic potential like them.

 

[Intuitive]

We know that a level Teaspoon of Neutrons weighs a billion tons but what does a level Teaspoon of Top Quarks weigh?

 

[arivero]

We know that a level Teaspoon of Neutrons

I didn't know. For instance a teaspoon of sugar gets one half of its weight from neutrons.

 

[Meir Achuz]

The top quark is about 200 times heavier than a neutron.
But, while the neutron has a radius of about .8 fm, the top quark could be a point particle so it depends on what you consider a teaspoon of tops.
Anyway, "teaspoon" is not an SI unit, and is not allowed in textbooks.

 

[superweirdo]

how are quarks formed and why do they decay?

 

[kmarinas86]

how are quarks formed and why do they decay?

http://particleadventure.org/particleadventure/frameless/quarks.html