Hans, I just realized that the branching ratios I gave, i.e. |e_r> -> |e_g> 50%, 25%, 25%, were probably incorrect. The reason is that when you compute a probability in QM you do it by taking
P = |<a|b>|^2,
and that means that the mass matrix has to be included four times, not twice. That means that the branching ratios actually are:
|e_r> -> |e_r> 66.67%
|e_r> -> |e_g> 16.67%
|e_r> -> |e_b> 16.67%
I realized that the numbers had to be wrong when I was working out the branching ratio from another point of view. This is somewhat speculative, so bear with me, please. Remember that the unusual thing about SU(3) color is that it appears to be a perfect symmetry...
Suppose that nature has a particle that travels at some fixed speed near the speed of light and exerts an extreme stress on space-time. The stress being very high says that the energy contained in the particle is very high. Nature wishes to reduces this stress by cancelling it.
Suppose that there is a hidden dimension, and the stress has sinusoidal dependence on that hidden dimension. That is, when you average the stress over the hidden dimension, you get zero, but when you integrate the square of the stress over the hidden dimension you get a number that corresponds to a very high energy per unit volume.
One way that nature could arrange to minimize the total energy of the particle is by ganging it up with another particle of the same sort, but arranging for the phase of the other particle, in the hidden dimension, to cancel the first. Thus you would compute the potential energy of the combined particles by first summing their stresses, and then integrating over all space.
Because the cancellation would depend on how far apart the particles were, this would result in a force. It turns out that the force that results from this sort of thing is, to lowest order, compatible with the usual assumptions about the color force. That is, the force is proportional to the distance separated.
The reason the calculation works out this way is quite generic. That is, any force based on minimization of a potential, with the potential having a nice rounded bottom, will be approximately harmonic. So this coincidence really doesn't mean much in and of itself.
If it weren't for the Pauli exclusion principle, nature could cancel the first with another particle traveling in the same direction. So nature instead reduces the stress by combining several particles traveling in somewhat different directions.
It turns out that if you analyze this problem from the point of view of Clifford algebra (that is, you assume that the stress take the form of a Clifford algebra), there is no way to get a low energy bound state out of two particles. Instead, you have to go to three. Details are beyond the scope of this post. So let's assume that nature combines three particles, with their phases (as determined by an angular offset in the hidden dimension) different by 120 degrees. The fact that 360 degrees divides equally into three multiples of 120 degrees gives the explanation for why SU(3) is a perfect symmetry, but the details are beyond the scope of this post.
Let's assume that the "center of mass" of the three particles travels in the +z direction. Let the red particle be offset in the +x direction, with the green and blue offset appropriately around the z-axis. The three particles travel on a cone centered around the z-axis.
Let the opening angle of the cone be \theta_b, where b stands for "binding angle". We expect that b will be as small as nature can get away with, but that it will be balanced by Fermi pressure. That is, if \theta_b is too small, the probability of the three particles being near each other goes down, and this raises the total energy.
Then the unit velocity vectors for the three particles are:
V_R = (s_b , 0,c_b)
V_G = (-s_b/2, s_b\sqrt{3}/2,c_b)
V_B = (-s_b/2,-s_b\sqrt{3}/2,c_b),
where s_b, c_b = sin, cos(\theta_b),
If the speeds of the individual particle are c', then the speed of the bound particle is c'\cos(\theta_b). If we assume that the bound particle is a handed electron, then this says that c' is faster than the speed of light by a factor of \sec(\theta_b).
In other words, the subparticles would have to be tachyons that travel at some fixed speed faster than the speed of light. There is some experimental evidence for the existence of this sort of thing. It consists of observations of gamma ray bursts. EGRET observed a double gamma ray burst with a delay of about an hour between bursts. It's called 940217 in the literature and there are plenty of theoretical attempts (failures) to explain it.
If the gamma ray burst were caused by a collection of tachyonic particles all traveling in the same direction, then a single burst of tachyons would generate time separated bursts of gamma rays as the tachyons traveled through regular matter if the regular matter was distributed into two lumps.
I made the argument that binons might be an explanation for high energy cosmic rays at the PHENO2005 meeting. There are about a half dozen good reasons for expecting exactly the odd sort of behavior seen in the Centauro events from a binon. The reasoning is beyond the scope of this post. I will soon get around to putting up a copy of the argument on the PHENO2005 website.
Anyway, the above description of a tachyon bound state would also apply to the left handed electron. Assume that the red for the left handed electron is also oriented in the +x direction, but the bound particle is traveling in the -z direction.
Then the unit vectors for the left-handed electron are:
Then the unit velocity vectors for the three particles are:
V_R' = (s_b , 0,-c_b)
V_G' = (-s_b/2, s_b\sqrt{3}/2,-c_b)
V_B' = (-s_b/2,-s_b\sqrt{3}/2,-c_b).
This means we can now compute angles between <R'|R>, and <G'|R>:
<R'|R> = s_b^2 - c_b^2,
<G'|R> = -s_b^2/2 - c_b^2,
<B'|R> = -s_b^2/2 - c_b^2,
The above give the cosines of the angles between the unit vectors. It's well known that probabilities in QM for things with an angle theta between them follow a law proportional to 1+cos(theta). After normalizing to unit probability, it turns out that the branching ratios do not depend on \theta_b. (This is also what you'd expect from relativistic length contraction in the z direction.) Instead, you get exactly the branching ratios that just happen to fit the fermion mass matrix:
P_{R'R} = 2/3,
P_{G'R} = 1/6,
P_{B'R} = 1/6,
Carl