Concerning the GZK cutoff: it seems to be there as predicted - seen in recent data both by HiRes (arXiv:astro-ph/0703099v1) and AUGER (arXiv:0706.2096, see Fig. 6). There will probably be more news next week from the International Cosmic Ray Conference ICRC’07 in Mexico. In the meantime, Bee at backreaction explains the GZK cutoff in detail.

It looks as if “boring” nuclear physics rules - data are consistent with interactions of cosmic ray protons with CMB photons as expected from boost invariance.

http://www.arxiv.org/PS_cache/arxiv/pdf/0705/0705.2171v1.pdf

http://www.arxiv.org/PS_cache/arxiv/pdf/0706/0706.3048v1.pdf

There are many other things, and I’ll try to post more when I get a little time.

http://en.wikipedia.org/wiki/Left-right_symmetry

Regarding the rest of your post, it really doesn’t make much sense to me.

This approach has many problems both in methodology and in checking it. 1) It assumes the Standard Model is totally correct at low energies and it assumes that forces do unify at very high energy. 2) It doesn’t make immediate predictions or post-dictions of the strength of gravity, cosmological effects, etc., that can validate the approach. 3) It doesn’t actually seem to make any long-term checkable predictions that are useful. 4) It doesn’t seem to make things simpler with regard to the Higgs field or the masses of different fundamental particles, which is the cause of most of the adjustable parameters in the existing Standard Model. 5) It doesn’t seem to help resolve existing problems in physics or to point in the direction of simple mechanisms to improve understanding. 6) It doesn’t get rid of U(1) at low energy, since U(1) emerges at low energy as a result of the symmetry breaking they are assuming. 7) It’s a theory built on speculation instead of on empirial observations.

SU(2) does have several advantages in describing leptons as doublets: pair production produces lepton-antilepton pairs. A conversion of 100% of positrons into upquarks and 50% of electrons into downquarks in the big bang would explain the alleged lack of anti-matter in the universe: it’s locked up by quark confinement in nucleons (the universe is mainly hydrogen, an electron, downqrark, and two upquarks). One simple mechanism based entirely on mainstream QFT is that the electric field of the core of a lepton is shielded by the polarization of pairs of virtual fermions around it. The virtual fermion pair production is, Schwinger showed, a result of the electric field of the electron core which extends out to about 1 fm radius where the electric field is above the threshold of 1.3*10^18 v/m required for pair-production. If at high energy in the big bang (very early times), N electrons were crowded together in a small space (against the Pauli exclusion principle), the polarization of the vacuum would be stronger, so the shielding factor due to the vacuum would be N times bigger. Thus, 3 electrons crowded together in a tiny space would still only give an overall electric charge of e; the contribution from each electron would be e/3 due to the extra shielding by the stronger polarized vacuum. This is just a simple heuristic mechanism for fractional charges. The energy conservation issue then comes to the fore: what happens to the 2/3rds of the electric charge energy (that is now being shielded by the stronger, shared vacuum polarization around the triplet)? Clearly, that energy is stopped at very short distances by the vacuum and used to produce loops of virtual particles which mediate short-range interactions. To avoid violating the Pauli exclusion principle (which would prevent a triplet of three identical quarks, since there are only two spin states available), colour charge must appear. This suggests that ‘unification’ of all forces doesn’t occur at very high energy: the colour charge is powered by short-range vacuum loop effects and decreases towards zero when you are close enough to the particle core that there is no room for the vacuum to polarize (i.e. no space for virtual fermion pairs to move apart along the lines of the radial electric field).

About chirality: it’s the discussion from Diogenes (#24) in “MiniBooNE Neutrino Result - Guest Blog from Heather Ray” that I didn’t get, but thanks for other background info:

You are completely correct, and this effect is included in the theory of neutrino masses as appears in standard texts. The projection of the neutrino spin along its direction of motion is it’s “helicity”. There is another measure of the “handedness” of a relativistic spin one half-particle called “chirality” that is easily defined in terms of the matrices appearing in the Dirac equation, and this measure does NOT depend on the reference frame in which you observe the particle. For massless particles these measures of “handedness” agree, but for massive particles they can disagree for exactly the reason you describe, ie. by moving past the particle you can reverse it’s direction of motion, hence it’s apparent helicity.

I don’t get the difference here, and which corresponds to plain “angular momentum”?