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## R c h o

I just come from the library and I strongly suggest to read the 1973 paper of Günayin and Gürsey ( JMP v 14 n 11 p 1651)
 Recognitions: Science Advisor I just came across this. RCHO extensively discussed, and O especially in the penultimate chapter, p273. http://books.google.com/books?id=DSF...page&q&f=false
 Are bosons non associative beins? Arivero wrote "who knows?". But, Cohl just use O^2 for the sake of completeness without mentioning the coincidence with the non associativeness of octonions. Ideas?

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 Quote by MTd2 Are bosons non associative beins? Arivero wrote "who knows?". But, Cohl just use O^2 for the sake of completeness without mentioning the coincidence with the non associativeness of octonions. Ideas?
At this moment, it is only an analogy, but seeing a "^2" makes me thing of a "sqrt()", and I can always compose two spin 1/2 to get spin 1 and spin 0. Is Cohl's "O^2" hidding some supersymmetry? If so it could be of some value for other approaches where only the bosonic part comes from the algebra, eg Connes's.

Every division algebra has an implicit hint of supersymmetry under the concept of "triality" or "generalised dirac gammas", as Evans call it.
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 Blog Entries: 6 Recognitions: Gold Member http://arxiv.org/abs/1010.3173 is a recent revisit to some pieces of the brane scanm sugra etc.
 Is there anything without supersymmetry? I really don't like it.

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 Quote by MTd2 Is there anything without supersymmetry? I really don't like it.
My own aproach of the sBootstrap, but it is fringe physics.
 Blog Entries: 6 Recognitions: Gold Member Seriously, it seems that the building of a manifold based of RCHO does not need supersymmetry, but so one could just leaving it and go Kaluza Klein all the way. But as Evans Duff and everyone shows, susy is really there and you must either observe it or to explay why you do not observe it. My own aswer was that the susy particles appear in the 4 dimensional world as composites, and that in fact we have observed them since the early fifties. Other answers can go in the lines of looking at it as an mathematical aparatus, avoiding it in the lagrangians, etc...
 What composites?

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 Quote by MTd2 What composites?
I told aboit it above in #50, and it is my thread in Independent Research. Not relevant hera except as motivation perhaps, it is a trick of my own: I kept thinking about the QCD string, and one day I noticed that the famous prerequisite for supersymmetry, to have the same number of scalar states and fermionic states, actually works for the particles bound with the QCD string if and only if you have three generations and a fast decaying top quark (so that it does not bind in the extreme of the string).

It is even madder than the maddest idea from supertring theory, but later I found that Schwarz himself was considering it in 1970 for six or seven months, and even published it in the Physical Review -so at least a referee considered it as a valid argument-. But he only considered susy between quarks and gluons, ie diquarks at most, and in the early seventies there was only one generation and half, everything light and well bound, so there was no grounds to follow this path.

Still, I kept to it always that I find susy: I think of muons and diquarks as if they were the susy partners, with the qcd string, of fundamental fermions. I prefer this way to the orthodox think, and it helps, because the link susy-triality-division algebras is very strong, so to close the eyes is not an option.
 Sorry, Arivero, if you'd got bored with this thread... You started with a Furey paper that cited FDT Smith's 1993 paper, then posted a link to Smith's home page. This contains a lot of stuff - most of no interest to me, whatsoever, but also much post-1993 including quite a lot of calculations that seem to be credibly close to the mark. I'd be very grateful if you could spare the time to give an opinion on Smith's approach, as he doesn't seem to have been explicitly considered in this thread (though i'm too layman to have recognised it, perhaps). Paul
 Blog Entries: 6 Recognitions: Gold Member Well, Paul, yes it is true that we have not touched Smith's in this thread, it is because I see it more as a pioneer - and an excellent bibliographer - than an active modelist. He did a lot of modelling in the nineties, went to congresses, showed his job, etc. With no results because, mainly and regrettably, the success of a model depends not on the physical content but on how useful it is for other researchers. And partly, because he was coming a bit late to the GUT pursuit, and people was surely tired of hundreds of models here and there. In the last fifteen years, of course, a lot of problems come with the bad interaction with establishment, arXiv and even web hosting... I think that in this time he has kept fine tuning his model -not sure if a good thing- and doing an excellent bibliographer task, but if he has got advances or he is stagnated somewhere, I can not perceive it.
 Thanks for that, Sir. Could someone help with another of my layman probs? Ghosts are usually thought to be wreckers in string theories. Do they pair with positive mass partners with identical quantum numbers? If so, what would be wrong with taking "reality" as the sum-of-squares mass (as in QM real/complex)?
 Blog Entries: 6 Recognitions: Gold Member Peter remarks on rcho http://www.math.columbia.edu/~woit/wordpress/?p=3665
 Something I've been wondering about since this thread came up originally: why does none of the 'physics-from-division-algebras' frameworks (like the one by Furey discussed in here, or Dixon's, Dray/Manogue, etc.) seem to contain any hint of supersymmetry? It seems that when you look at supersymmetry, division algebras stare right back at you, but when you look at division algebras, supersymmetry appears much more coy...

So, I've been thinking about, and reading up on the history of, this RCHO business on and off for a few months, and I'd like to take a new look at it...

First of all, Geoffrey Dixon has a new book out ('Division Algebras, Lattices, Physics, Windmill Tilting'), but I haven't gotten my hands on it (yet).

Also, it's been said that it's hard to get the Higgs in the division algebra approach, but it seems that it was actually there, in some sense, in one of the earliest attempts (which I don't think has been mentioned in this thread so far) by Finkelstein, Jauch, Schiminovich and Speiser: they used a 'principle of general q-covariance', i.e. invariance under transformations of the form $\Psi\to q\Psi q^{-1}$, and find a massless boson (photon), and two additional massive, charged vector bosons ($W^{±}$). Tony Smith calls it:
 the first paper [...] that used Quaternionic SU(2) symmetry to describe the mechanism whereby two charged SU(2) bosons get mass, and the electromagnetic field is unified with the SU(2) bosons. Their paper effectively did the "Higgs Mechanism" before Higgs, and did ElectroWeak Unification before Glashow,Salam, and Weinberg

They don't find the $Z^0$, perhaps related to the fact that they only use SU(2), rather than the full U(1)xSU(2) (i.e. $ℂ\otimes \mathbb{H}$).

The paper 'Octonionic Structures in Particle Physics' by Gürsey gives some fascinating insight into the history of the subject, in particular how octonionic extensions of quantum mechanics were originally looked into in order to incorporate the new phenomena of nuclear physics before the advent of gauge theory. Some other interesting papers (some of which will probably have been mentioned already):
'Remark on the Algebra of Interactions' - A. Pais (an early one, 1961)
'Octonionic Quark Confinement' - H. Ruegg (related to the idea that the non-associativity of the octonions ensures the unobservability of quarks; in a sense, a special imaginary unit is picked out, which gives us our usual quantum mechanics, and has the side effects of breaking $G_2$ to SU(3), and bringing $SL(2,\mathbb{O}) \simeq SO(9,1)$ down to $SO(3,1)$. Under this SU(3), the split-octonion units $u_0 = \frac{1}{2}(e_0+ie_7)$ and $u_0^* = \frac{1}{2}(e_0-ie_7)$ transform as a singlet and antisinglet, while $u_i = \frac{1}{2}(e_i+ie_7)$ and $u_i^* = \frac{1}{2}(e_i-ie_7)$ (i = 1,2,3) transform as a triplet and antitriplet -- a lepton and quark, together with antiparticles. (This is of course the familiar Günaydin-Gürsey scheme.) So this gives us 'half a generation' of fermions living in Minkowski space.)
'SO(8) Color as a Possible Origin of Generations' - Z.K. Silagadze (discusses a possible extension of the above to incorporate a full generation, then uses SO(8)'s triality to find the observed three.)
'Algebraic Realization of Quark-Diquark Supersymmetry' - S. Catto (related to my question above; 'composite' SUSY from octonionic color algebra -- arivero, I think, is familiar with this)
'Quaternion Higgs and the Electroweak Gauge Group' - DeLeo, Rotelli (another look at Higgsing from a div. alg. perspective)
'Derivation of the Standard Model' - Dixon (I think this is the first paper where Dixon lays out his model, or its basics, completely; of course, the full treatment is available in his first book (most of which I don't understand, unfortunately))
'Algebraic Approach to the Quark Problem' - Casalbuoni et al (a somewhat alternative approach to that of Günaydin/Gürsey, explaining the quark confinement through the realization that in a path-integral quantized version of their theory, only color singlet states can propagate)

There's many more, but this post is already getting rather lengthy, and there's one last, perhaps somewhat too out-there, thing that I've come across that I wanted to share. In entanglement theory, there's an interesting connection between two- and three-qubit entanglement and the Hopf fibrations, and hence, the division algebras, laid out in the paper 'Geometry of the Three-Qubit State, Entanglement, and Division Algebras' by Bernevig and Chen, and summarized in the slides to this talk by Chen. The idea is, basically, that the Hopf map is sensitive to the entanglement properties of two- and three-qubit systems: the state space of one qubit is given by the first Hopf fibration, $S^1 \hookrightarrow S^3 \to S^2$, where the $S^3$ is the qubit state space, the $S^1$ fiber is the global phase, and $S^2$ is the Bloch sphere. Analogously, the state spaces of two- and three-qubit systems, $S^7$ and $S^{15}$ can be related to the second and third Hopf fibrations, $S^3 \hookrightarrow S^7 \to S^4$ and $S^7 \hookrightarrow S^{15} \to S^8$. Of course, there are no more Hopf fibrations after that, because there are no more division algebras beyond the octonions. In each case, the fiber is the unit sphere of the complexes, quaternions, or octonions respectively, while the base spaces are the respective projective lines. This map is entanglement sensitive in the sense that if, for instance, the three-qubit stat is biseparable, it maps only into the complex subspace of the octonionic projective line. Furthermore, each base space can be seen as containing one qubit, plus the entanglement degrees of freedom, while the rest of the state (two qubits for the three qubit case, one for two qubits) lives in the fiber.

Now this is quite a surprising way for the division algebras to turn up in entanglement! In particular, this appears to allow us to consider a two-qubit state as a single quaternionic qubit, and similarly, a three-qubit state as a single octonionic qubit (essentially via the Cayley-Dickson construction: if two qubits are parametrized by the complex numbers $\alpha_k = a_k + ib_k$, k = 1...4, then it can be parametrized by the quaternions $q_1 = (a_1 + ib_1) + j(a_2 + ib_2)$ and $q_2 = (a_3 + ib_3) + j(a_4 + ib_4)$, where $j^2=-1$ and $|q_1|^2+|q_2|^2=1$; an analogous construction works for the three-qubit case). (The connection between Hopf fibrations and qubits over division algebras was also noticed in the paper 'Extremal Black Holes as Qudits', by M. Rios who I think posts here occasionally.)

But this brings us right to the quaternionic and octonionic extensions of quantum mechanics discussed earlier! So, could there be a connection? (Probably not, but it's just the kind of '...but what if?'-thing that sometimes goes through my head at night...) In particular, since I've always liked the 'spacetime is made of qubits'-idea from Weizsäcker's ur-theory, to look for 'inner space' in entanglement between urs seems somehow appealing to me... But I realize this is just far-out speculation.

In any case, this has gotten somewhat lengthy, so thanks to anyone who persisted to this point; I'd be very glad for any comments, especially elucidations of things I don't quite grasp yet (my background is not in particle physics, so this is not really my home field...).