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satori
2007-Jan-28, 12:08 PM
Hallo Bjoem, i see you are around,
could you please give a short explanation as to why quarks can't break free?

trinitree88
2007-Jan-28, 01:32 PM
Hallo Bjoem, i see you are around,
could you please give a short explanation as to why quarks can't break free?

Satori. The binding of quarks in a hadron is due to the color force. A constant exchange of color charge between members is mediated by color gluons...the "glue" that holds them together. The mystery of the lack of solitary or "free" quarks is thought to be due to the fact that the energy required to remove a quark exceeds the value necessary to produce a quark/anti-quark pair....so as the quark is just about asymptotically free from it's partner, it suddenly is gifted with half of the new pair. The other half snaps back to the original position leaving the original count intact and birthing a meson in the process instead of a free quark.
So the thinking goes, you can't break a single quark free, and a pair is a meson, which is what we always see. Pete

satori
2007-Jan-28, 05:38 PM
thanks for the expl. trinitree!
(let me mention in passing that your name brought me to this site in the first place namely by "trialgooogeling" it for fun)
In reading your reply i was remembered to having read once about speculative strangestars ( that would be your conventional neutronstar with free strangeness for a charge).
is that one still on the scene?

trinitree88
2007-Jan-28, 08:39 PM
thanks for the expl. trinitree!
(let me mention in passing that your name brought me to this site in the first place namely by "trialgooogeling" it for fun)
In reading your reply i was remembered to having read once about speculative strangestars ( that would be your conventional neutronstar with free strangeness for a charge).
is that one still on the scene?

satori. You're welcome. lol...reminds me of the movie"The Gods Must Be Crazy"..somebody Googles my name...lol. Anyway, to your question, there are six quarks: First Family....up with down. Second Family....strange with charm. Third Family: top with bottom.
In your conventional neutron star, there are more than just neutrons, there are protons,electrons, neutrinos of sorts. Within some of the neutrons, (two downs and an up)...a quark can convert to a strange quark with the weak force at work..(it's endothermic and requires an energy input). This newbie has strangeness, a quality that allows for a relatively slow decay scheme, as all strange particles do (the strangest is the omega minus, with a triple dose). So you don't have "free" strangeness anymore than you have free quarks elsewhere, you have transmuted a fairly mundane baryon (the neutron), into a hyperon with a single unit of strangeness. If this happens to a large degree, and most of the neutrons and protons are so converted, then you have a strange star. At what exact percentage you require to define this I'm not sure I've ever seen that. (Spaceman Spiff, Phil, Eta C,KenG, TimThompson, DonAlexander, Antoniseb, etc...might know). In theory, the strange star should be of higher density since it has a greater mass-energy per particle, but the degeneracy pressures models and calculations are a subject of some controversy yet. (I asked this question of Jerome Friedman at MIT in 92, it was even more "iffy" then). Pete

satori
2007-Jan-28, 10:32 PM
thanks a lot, i will be back, good night.

(....ehmm , yes, STRANGENESS HAPPENS.....)

Mister Earl
2007-Jan-29, 07:05 PM
Hrm. Could something be constructed of two quarks instead of three? Four quarks? What would prevent such a formation?

trinitree88
2007-Jan-29, 07:53 PM
Hrm. Could something be constructed of two quarks instead of three? Four quarks? What would prevent such a formation?

Mister Earl. Two quarks make up one of the many mesons. I think I once saw some evidence for a transient 4 quark assemblage, but not in any way stable. Threes and twos seem to be the Standard Model's repertoire.Pete.

ozark1
2007-Jan-29, 08:27 PM
I don't know about four, but five quarks does exist - the pentaquark discovered in 2003.

ozark1
2007-Jan-29, 08:33 PM
Oh, and to add to the discusions of Confinment from earlier.

Single Quarks do not / cannot exist because the colour force is independent of distance. As the energy in such a bond increases with separation, eventually there is enough energy to form a quark-antiquark pair.

All particles are colour neutral (white) because of this.

Celestial Mechanic
2007-Jan-29, 09:08 PM
Hrm. Could something be constructed of two quarks instead of three? Four quarks? What would prevent such a formation?Only color neutral combinations can exist. Two quarks would not be color neutral, but a quark + antiquark combination would be, and that is how most mesons are built. Three quarks (or three antiquarks) can exist in a color neutral combination, and that is how baryons (and antibaryons) are built.

Some other combinations are:

Two quarks + two antiquarks, I think some candidate states have been found.

Four quarks + one antiquark. This is the so-called "pentaquark", a few resonances have been found.

Three quarks + three antiquarks. These are called "dibaryons" because they could be thought of as a virtual baryon-antibaryon state. They've been searched for but not yet found.

Also, since the gluons carry the color charge it is possible to combine two or three of them (and possibly more) into a color neutral particle called a "glueball". Most glueballs (though not all) have identical quantum numbers of various electrically neutral mesons, it is possible that some of the particles that we see are actually glueball/meson mixtures. There are many questions here.