# Quark Binding Energy

1. May 23, 2007

### losang

I am aware that quarks can not be separated due to the strong force growing with distance. My question is, instead of pulling them apart can you "remove" the energy between them and therefore separate them. There are two ways I have thought about this. One, the technological question of can you remove the binding energy and second is it theoretically possible.

2. May 23, 2007

### malawi_glenn

It is not pracically possible, how would you remove the force field? Well the force field is just interacting with particles carrying the strong (colour) force. So in order to remove the field quanta (the gluons) you must use strongly interacting particles, witch in their own turn carries a force field.. and so on..
have you studied elementary particle physics at college?

3. May 24, 2007

### marlon

No you cannot since the force field is an inherent quark property (just like you cannot remove the electrical charge from electrons). To reduce the strong force between quarks, you gotta make sure they are not in the ground state because the strong force is "strongest" at that energy level. So, intuitively, you might wanna speed up those quarks. High velocity quarks are less tightly bound !

marlon

Last edited: May 25, 2007
4. May 25, 2007

### CraigD

Also remember that quarks have a nature of partial charge, 1/3, 2/3, -1/3, -2/3 (Double check the charge states). And much like a monopole, a particle with a partial charge has never been observed in nature. We see quarks always together to either form one of three charge states, 1, -1, 0.

As Marlon said, try speeding them up, that is part of the hope for the LHC.

CraigD, AMInstP
www.cymek.com

5. May 25, 2007

### losang

Great answers from everyone. Thank you. Related to CraigD's post. What is the reasoning behind there being three quarks with fracitonal charges that can not be separated as opposed to a single particle with unit charge?

6. May 25, 2007

### humanino

The argument is that fractional electrical charges must somehow be confined anyway because they have never been observed. It is quite a bold point of view. Confinement having something to do with the electroweak sector !? I totally disagree.

FYI fractional electrical charge carriers have been observed. Not as fundamental particles however.

7. May 25, 2007

### losang

Yes but why were fractional charges proposed in the first place?

8. May 28, 2007

### marlon

One way to explain this is using group theory. The equations (ie Lagrangian) describing quark interactions need to respect certain symmetries, eg rotational symmetry. To respect this demand, the quark wavefunctions need to behave in a certain way under these spatial rotations. If you elaborate on this, you can prove that quarks need to have certain values for spin, angular momentum and electrical/color charge.

Another way to explain this is the Dirac quantisation theorem that follows from the Dual Abelian Higgs model : to product of electrical charge e and magnetic charge g is constant and equal to $$2 \pi n$$ (n is an integer). So the existence of a magnetic monopole leads to the quatisation of electrical charge.

marlon

9. May 28, 2007

### losang

OK, but the question still stands. Why were quarks proposed in the first place.

10. May 28, 2007

### marlon

No that's a different question with respect to "why fractional charges".

Experimentally quarks were discovered in the late 60ties and early 70ties by scientists doing electron-proton scattering experiments at SLAC. High energy electrons were scattered off protons/neutrons. The results showed more electrons bouncing back with high energy at large angles than could be explained if protons and neutrons were uniform spheres of matter.

http://www2.slac.stanford.edu/vvc/nobel/1990nobel.html

If you are looking for a theoretical introduction of quarks, you wanna look for the eightfold of Murray Gell Mann.

marlon

11. May 28, 2007

### humanino

Marlon gave you very accurate responses and references. I will just add one thing. It is not a straightforward issue Marlon mentionned group theory. Indeed, Murray Gell-Mann introduced "quarks" to classify the observed hadronic spectra and make predictions for mass ratios, magnetic moments etc... But he himself did not believe at that time that quarks were real particles ! Only once scaling was observed at SLAC, people started to believe in Feynman's partons (hadronic constituents, quarks and gluons namely) and only even later were Feynman's partons identified as Gell Mann's quarks !

12. Jun 4, 2007

### losang

Good point. I had the question in my mind but it didn't come out very clear. This sounds very similar to how it was show that the plum pudding model was incorrect.