Tuesday, October 4, 2011

More faster-than-light neutrino speculation

Continuing perusal of the arxiv.org papers,

In http://arxiv.org/pdf/1109.5917v1, say that tachyonic neutrinos are positively ruled out because it would also require a violation of the conservation of energy, "a tachyonic interpretation is not only hardly reconciled with OPERA data on energy dependence, but that it clashes with neutrino production from pion and with neutrino oscillations."  They further explore some papers from the 90s by Coleman and Glashow that suggest test for the Lorentz equations in cosmic rays and accelerators.  Their basic suggestion is that neutrinos have their own limiting velocity that is different from (and possibly greater than) the speed of light.  This hypothesis is contradicted by neutrino oscillation experiments.  Oh well.

In http://arxiv.org/PS_cache/arxiv/pdf/1109/1109.6641v1.pdf, the authors work very hard to reconcile the SN1987a neutrino results with the OPERA results.  To review, the supernova neutrinos arrived 4 hours earlier than the light from the supernova (over 160,000 years--2 parts in a billion deviation).  Of course, the OPERA neutrinos are faster than light by 50 parts in a million.  Their main assertion is, obviously, neutrinos travel faster in Earth than in inter-galactic space.  OK.  Right.

In http://arxiv.org/PS_cache/arxiv/pdf/1109/1109.6282v1.pdf, the authors suggest, "the existence of light sterile neutrinos which can propagate in a higher dimensional bulk and achieve apparent superluminal velocities when measured by an observer confined to the 4D brane of the standard model."  That is, they find a shortcut in the extra dimensions (needed by many versions of String Theory) of space.  But only "sterile" neutrinos can do this, as "fertile" ("dirty"?) neutrinos are confined to be in our regular old four-dimensional space.  But OPERA measures muon neutrinos--they aren't sterile.

In "Superluminal Neutrinos without Revolution" by Susan Gardner of the University of Kentucky, she speculates that neutrinos are unique in that they do not interact with the "dark universe" like the rest of the particles.  Regular particles are slowed down by this interaction.

None of these are at all satisfying.

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