It has already been noted that in the Standard Model the merging of two complex wave functions into a wave function of a single entity is not based on structural considerations, but, instead, on a mathematical model. This model is based on the principle that if two wave functions are taken together into a composite wave function written as a matrix, the matrix must satisfy the special property of “unitarity”. If not, the assembly does not satisfy the semantics of a valid wave function. This SU(2) property is not a result of a physical proof, but rather the reverse. Assuming that two particles can be seen together as a unit, their individual wave functions must be written as a SU(2) doublet. It is for this reason, for example, that the decay product of a pion, which itself is built up as a doublet , must be a SU(2) doublet as well. So, a muon together with the muon antineutrino is an SU(2) doublet as well. The same applies to the electron-antineutrino doublet generated by the decay of a neutron into a proton. In 1970, a fourth quark was discovered from a newly discovered meson with mass 3.1 GeV/c2. The electric charge of this new quark, called charm ( ), was opposite to that of the quark. In 1976, a third lepton was discovered, named as tau, followed a year later by another new meson. This time with a mass of 10 GeV/c2, which could only be explained with a fifth quark, named as bottom ( ). Because three SU(2) lepton generations had been found, it was assumed that, like the doublet , the newly found quarks had to be regarded as three SU(2) doublets as well. So, and On the basis of this heuristic, the sixth quark was predicted in 1973 by Makoto Kobahashi and Toshihide Maskawa. In 1995 a particle was discovered with a mass of 173 GeV/c2, with properties like those of a quark. That discovery has been seen as a triumph for science and as further proof of the validity of the Standard Model. That the mass of this particle is completely out of range in the series of the constituent masses for and of 0.5 GeV/c2, 1.5 GeV/c2, 4.7 GeV/c2, respectively, was not (?) experienced as problematic.
While the axiomatically constructed SU(2) model relies on an empirical interpretation of particles and their attributes, the structural model provides answers with predictive scope (unfortunately only a posteriori). The mechanism by which new mesons and quarks arise is easy to understand. The simplest explanation is that in which one imagines that the energy of the first excitation of the pion modelled as an anharmonic oscillator is taken over by the ground state of two heavier quarks. However, the mechanism also allows only one of the two to be heavier and the other quark to remain as it was. Therefore, the kaon is not built up as
but as
or by the variants
en
.The generated new quark
has different numerical values for
and
, while preserving the invariance
. Why the ratio is invariant will become clear later. The scope of this essay does not allow detailed calculations. These can be found in documented work [
8,
9]. In that work it is shown that the meson mass spectrum can accurately be calculated from the base (
) quark. The same holds for the calculation of the constituent masses of the
and
quarks. These masses are the masses that can be attributed to the quarks as contributions to the energy of the hadrons (mesons and baryons). Since the masses can be calculated, the quarks, apart from the base quark, cannot be considered elementary. They are scaled versions of the base quark. As for the quark masses, it should be noted that since the emergence of the lattice QCD (Wilson, 1974), the convention as constituent masses has been abandoned for the light quarks quarks
and
, while those for
and
for the time being have been maintained [
10]. That doesn't seem very consistent. While the masses of the light quarks have been recalculated as so-called "running mass" from a theoretical concept that is still under development, this has not yet happened for
and
.
Besides the axiomatic SU(2) concept, unlike the structural model, imposes defining the quark flavors as elementary particles, there is another important difference. The structural model does not allow for quarks heavier than the bottom quark. The excitation mechanism in the anharmonic oscillator model is accompanied by a loss in binding energy as the quarks become more energetic. Therefore, as noted earlier, the bottom quark cannot have an isospin partner. This means that the top quark, the mass of which is completely out of range, must have a different interpretation. Which one will be made clear later in the essay. in the SU(2) concept the view that the bottom quark must have an isospin partner has no other justification than wishful thinking for classification, associated with the three lepton generations.
The baryons
With the establishment of the GSW theory, it was believed that the weak force was accurately portrayed as weak interaction. Strong force and strong interaction, though, remained a puzzle to be solved. That in the SU(2) model the strong interaction is implicit by accepting the Higgs potential has not been recognized because, in the absence of a physical interpretation of isospin, no structural interpretation for the SU(2) model was available. While with the SU(2) model the question of how quarks in isospin doublets, such as mesons, are glued together could in fact be avoided by a mathematical model, this question fiercely pops up in a baryon configuration.
Before discussing the theory in the Standard Model that aims answering the question, let's set up a simple structural model just like the meson.
Figure 4 shows a structure illustrating that the repulsive interaction between monopoles can be compensated by an attractive interaction between scalar dipoles in suitable orientation. This equilibrium state is the result of the liquid drop model of the interquark potential. It should be noted that, for the time being, the polarities of the dipoles don’t need an electrical interpretation.
Figure 4.
Structural baryon model: the repulsive forces between the monopoles are balanced by the attractive forces of well-oriented dipoles.
Figure 4.
Structural baryon model: the repulsive forces between the monopoles are balanced by the attractive forces of well-oriented dipoles.
This model can be described as a “one body” equivalent of a “three-body” harmonic oscillator. This structure is only fully symmetrical if the three quarks all are in the same spin state, because, as we have established, the nuclear spin interaction has a significant influence on the force balance between the quarks. This means that the sketched figure relates to, for example, a Δ+++ baryon (i.e. three quarks with spin 1/2, or a baryon (three quarks with spin -1/2). In the historic development of the Standard Model, such a configuration has been conceived as if three equal quarks were in the same state of energy. However, the Pauli exclusion principle prohibits an equal state of spin for two identical fermions in the same state of energy. A new axiom is the simplest way to break the deadlock. The new axiom is the assignment an extra attribute to the quarks, namely, in addition to electric charge, a second type of charge: a color charge red, green or blue. This can make each of the quarks different from the other quarks, under the requirement of the complementing white color for three color charges. There is a second problem with the baryons to solve as well. Because the electric charge of all mesons and baryons is equal to the charge of a single electron or, in the case of some baryons, to the double of it, and because a baryon consists of three quarks, the elementary electric charge has been broken up by axiom into two pieces 2/3-1/3, so that quarks either have a charge , or .
Without disputing in this essay the logic of these two axioms in this essay (they enable successful interpretations of many particle experiments to date), the axioms are mere hypotheses, because neither color charge, nor broken electric charge, can directly be experimentally proven. Experiments are usually interpreted with an axiomatic theory as a presupposition. As long as no conflict is found, the theory is considered as being correct. Nevertheless, both axioms are weak. Attributing color charge to quarks is justified on incorrect grounds. It happened on the assumption that the baryon
wave function is a ground state. A simple parallel with electrons in orbits around an atomic nucleus shows that caution is required here. After all, the orbits of two electrons with the same spin can be almost the same, but may slightly differ in state of energy. The energy difference is caused by the electrical interaction between the two electrons. Something similar happens in the
baryon, which can be seen as an excitation from a nucleon [
26] .
Figure 4 relates to the two nuclear forces that together determine the interquark potential of quarks. The interaction between electrical behavior is not included. If one does, then the three quarks will assume a different state of energy with respect to each other. Whether this should be modelled with color charges is highly questionable. Anyhow, as to be shown later, it can be done without as well. With regard to the broken electric charge axiom, it should be noted that it arises from the wish to regard electric charge of mesons and baryons as the sum of charges of individual quarks. An assumption that electric charge arises from interquark interactions and therefore might be a holistic attribute of meson or baryon as a whole is equally legitimate. This will be explained in more detail later as well.
However, the symmetry of the structural model now raises the question of why five baryons are asymmetric in their electrical behavior. After all, the positive charge of the baryon is twice as large as the negative charge of the baryon . The symmetry between these spin 3/2 baryons seems being disappeared. The spin 1/2 baryons from which they are excited, the proton and the neutron, are already asymmetrical as well. However, if the antiparticles are included in the scheme, the symmetry for these spin 1/2 baryons as well as for the related spin 3 /2 baryons is fully recovered. The loss in symmetry therefore arises from the difference in stability between the electron and the positron as its antiparticle. Other elementary particles show a similar difference as well. Such a difference in parity is basic in our universe. Without it, a stable universe is unthinkable.
In the Standard Model, a different route has been chosen. The formulation of the color charge axiom has led to the extension of the isospin SU(2) doublet of two nuclear particles to the color charge SU(3) triplet of three nuclear particles. By considering isospin as a carrier of electric charge (to what extent this is undisputed will be discussed later in this essay), the parallel SU(3) annex color charge and SU(2) annex electric charge seems plausible. Because, according to the color charge hypothesis, a quark is made up of three color charge components, the wave function of the quark is not twofold, as in the isospin doublet, but threefold. In its simplest form, the wave function of the SU(3) triplet is represented as a 3 x 3 matrix,
The components of the three constituent wave functions of the triplet are complex quantities. Because the wave function of a doublet consisting of, for example, two quarks bound together, as with a pion, must be seen as a single entity, with the associated semantics, the SU(3) matrix, just like the isospin doublet, is unitary , i.e. ⴕ = . However, the number of degrees of freedom n – 1 is now eight instead of three as in the doublet.
If the wave function of the triplet is made subject to a conservative force field, the semantics is preserved under covariant conversion of the wave function of the triplet ,
in which
are the eight 3 x 3 are Gell-Mann matrices, which, in the color charge triplet, are the equivalents for the three Pauli matrices in the isospin doublet. Based on this analogy, in the Standard Model eight new bosons, called gluons, have been conceived. These are seen as force-transmitting particles that in the triplet maintain the bond between the quarks.
Although the necessity of assigning the color charge attribute is disputable, modelling the wave function of a three-body entity as a SU(3) group is legitimate. However, the question now arises whether the gluons conceived in this way have more than an abstract meaning. And even, if it is legitimate to refer to them as media for strong interaction, are they the carrier of the strong nuclear force? Isn’t true that, as pointed out before, that the strong nuclear force is already included in the Lagrangian of the isospin doublet? Which physical phenomena can be explained with Quantum Chromo Dynamics (QCD) that are otherwise inexplicable? Have gluons been observed experimentally? Questions that arise because the assignment of the color charge attribute has been based on incorrect argumentation.
The concept of compiling covariant descriptions for the weak interaction and the strong interaction, based on the SU(N) group formalism of Sophius Lie from 1873, was originally described in 1954 by Chen Ning Yang and Robert Mills. However, in the Yang-Mills theory, just like in electromagnetism, the gauge fields have an unlimited range and the bosons are massless. In the 1967 GSW theory, the concept was made valid for SU(2) by inclusion of the Higgs field. About 1964, after identifying the quarks as building blocks of the nuclear particles, the SU(3) description was drawn up, more or less simultaneously by Murray Gell-Mann and by George Zweig, for the interaction mechanism between three quarks. So their gluons are massless. That was well before the introduction of the color charge hypothesis by Harald Fritsch, William Bardeen and Murray Gell-Mann in 1972.
Since the SU(3) description makes the gluon massless, their range seems unlimited, while the strong force should have the opposite effect of extremely small range. This paradox is explained in the Standard Model by pointing out that gluons mutually exchange their color charge, so that gluons are linked by strings. This limits their range. Again a new assumption that is not experimentally verifiable, but which cannot be refuted if experiments are interpreted on hypothetical grounds.
Instead of extending the abstract SU(2) model to the possibly even more abstract SU(3) model, one could have opted for a structural approach. In that case, one encounters a notoriously difficult three-body problem. The interaction between three particles, such as quarks in a nucleon, also occurs in the H3 molecule, as an interaction between three atomic nuclei. The analysis that in 1990 P. Bartlett and B.J. Howard [11] developed for this purpose can be applied to the interaction between three quarks as well. This problem appears to be solvable by using the interquark potential derived from the liquid drop internucleon model. The more so because, as we have seen, an analytical relationship for it is available. While a particle doublet, such as a meson, can be modelled as a "one-body" equivalent of an anharmonic "two-body" oscillator, a particle triplet, such as a baryon, can be modelled as a "one-body" equivalent of an anharmonic “three body” oscillator. This appears to be possible by the use of pseudo-spherical coordinates as in 1968 developed by R.C. Whitten and F.T. Smith [12]. The Smith-Whitten coordination system is six-dimensional. In addition to a hyperradius , the square of which is equal to the sum of the squares of the spacings between the three particles, there are five angles

, in which

and

model the changes in the shape of the triangular structure and in which

and

are the Euler angles. These are angles that determine the orientation of the triangle in 3D space. The interaction forces between the three particles not only cause dynamic shape changes in the equilaterality of the structure, but they also cause a Coriolis effect that results in vibra-rotations around the axis of the moment of inertia of the three-particle structure. Altogether, this results in a wave equation with the format of an anharmonic oscillator, which can be written as [13],
In which
;
;
, and
This format bears close resemblance to the wave equation for the meson discussed earlier. It is made up of the same parameters as those derived from the interquark potential. One of the main differences is the presence of the “grand angular quantum” number in the wave equation. For the ground state
, so that
As in the case of mesons, it appears that mass ratios for baryons can be accurately calculated with the anharmonic oscillator model as well. The calculated mass ratio of the excitation from ground state to first excitation is 1.475, which corresponds almost exactly to the experimentally determined masses for nucleon (938.3 and 936 MeV/c2) and the excited baryon (1382.7, 1383.7 and 1387.2 MeV/c2).
The structural model confirms that the strong force is an inherent component of the interquark potential. Just as the oscillator model of mesons can be deduced from a Lagrangian with interquark potential, it can be deduced for baryons as well.