Can you get strings of more than three quarks without any anti-quarks? I am just trying to find out if such structures have been observed as a way to possibly explain bound states of neutrons and protons through gluonic binding rather than a nuclear force.
The Lund string that we use in the Pythia event hadronizer is naively constructed from a quark-antiquark pair with gluon kinks on it that arise from the evolution of quarks, antiquarks, and gluons. To handle baryons, we have an object called a "junction" which is a combination of three strings stretched between the three quarks. So, yes, insofar as the Lund string corresponds to real Quantum Chromodynamics, the binding of the proton, or the hadronization of a 3-quark system can be understood through strings.
I remember vaguely that some theoreticians postulate a possibility of a string fusion process due to their overlap in very high energy proton proton or nuclear collisions. I am not sure this possibility is implemented in any of the event generators like Pythia, Phojet or UrQMD. But this is probably not a subject of this question.
It is hard to answer w/o knowing the big picture. A QCD string connects two colored objects that sit on both sides. Looks to me that if you try to put more than 3 quarks at the end of a string the colors o some of them will form a color singlet and cancel out. I'm not sure if you can have two same-color pairs of quarks in the same string due to spin statistics
Here is a description of the junction topology with some references:
http://home.fnal.gov/~mrenna/lu_update/lutp0613man2/node201.html
Art75
X. Artru, Nucl. Phys. B85 (1975) 442;
L. Montanet, G.C. Rossi and G. Veneziano, Nucl. Phys. B123 (1977) 507
String junctions are relevant in the baryon transport process which results in a given ant-baryon to baryon ratio in the central region (far from the initial beams in rapidity).
At low (SPS) energies this ratio was significantly lower than one while at LHC (much larger rapidity range) this ratio becomes essentially compatible with one indicating that string junctions have a limited probability to be transported far away in rapidity.
The kind of model you are looking for already exists to describe hexaquarks: http://arxiv.org/abs/1111.5921 .
There may be a phenomenological problem with using this type of model for nucleons. The string energy grows linearly with the string length. Therefore, the string potential energy is infinite at long distances. However, the neutron and proton potential is short range.
If you wanted to fix this problem, you could include string breaking effects: http://prd.aps.org/abstract/PRD/v35/i3/p907_1 . However, some of these flux-tube/string breaking processes will produce mesons. Therefore, it seems as though meson exchange would emerge from this type of model.
Each pair of quarks generates an electrical field E which "move" the monopoles current, that, at its turn creates a electro-magnetic field B which "press" the above electric field, that forming a flux tube. The Higgs boson and Z are not particles, they are the results of the interaction between hadron flux tubes, as I have shown in my works!
I was wrong about the particles viewed as micro-Black holes, my last computation show that is neded to concentrate a mass of 10^11 Kg in 1.e-16[m], that is imposibile. So apologize, please forgot this part of my comentary.
Hi Sanjay,
You description from Dec 14th is accurate. Some models and simulation programs use the concept of a one-dim string that extends from one color charge to the other to "explain" the formation of jets. Such color strings carry, indeed, energy that growth linearly with their length (confinement). But these strings are typical to high energies when the strong coupling constant is relatively small. The neutron and proton are low energy bound states of quarks. The strong coupling constant is very large and I don't think you can apply the notion of a string to these states. One can compute their properties, e.g. mass with latice QCD but this is a different opera
I wrote my dissertation thesis about the fission of hadrons using a simplified model of heavy quarkonia. You can find it (sorry, it is in German) in my publication list. The mechanism is the squeezing of colour fields between two colour charges in a baglike cavity sitting in the QCD vacuum that leads to supercritical states resulting in a spontaneous pair creation of light quarks that will shield the colour field. The supercritically occurs at a certain distance between the heavy quarks and correspondes to a maximum excitation energy of the quarkonium system.
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