neutrinos

ICARUS weighs in; but we knew this

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Another experiment has weighed in on superluminal neutrinos — indirectly.  The ICARUS experiment has measured the energy spectrum of neutrinos traveling from CERN to Gran Sasso.  They confirm that the Cohen-Glashow effect, which I described in some detail here,  is not occurring in the beam of neutrinos that OPERA is also using.  The distribution of … Read more

Another Speed Bump for Superluminal Neutrinos

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Here’s another major strike against the OPERA experiment’s claim of superluminal neutrinos, in addition to the Cohen-Glashow argument I described last week. It comes from a very natural place: the weak nuclear force. The theory (i.e. the equations) that we use, with great success, to predict the behavior of the weak nuclear force inextricably links some of the properties of neutrinos and charged leptons (electrons, muons and taus.) Because of this linkage, you simply can’t make neutrinos travel faster than light without making electrons do it too — by a smaller amount, to be sure, but still bigger than a part in a billion. And it turns out the effect is large enough that it should already have been detected by existing experiments, putting OPERA’s result further in doubt.

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Is the OPERA Speedy Neutrino Experiment Self-Contradictory?

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While I was busy with last week’s LHC workshop in London, a very interesting and short paper appeared, written by two of the world’s experts on violations of “Lorentz invariance”, the symmetry of space and time that underlies Einstein’s theory of special relativity. The authors, both from Boston University, are Andrew Cohen, who is highly regarded within the community for several significant contributions to high-energy physics, including his co-authorship of the key papers that led to the theory of a composite Higgs field known as “Little Higgs”, and Sheldon Glashow (formerly at Harvard), Nobel Prize winner for his work on the weak nuclear force, and famous for many other contributions of nearly equal importance.  In the 1990s, Glashow, with the late great physicist Sidney Coleman, (highly respected not only for his exceptional theoretical research but also for his beautiful scientific writing and extraordinary teaching ability), wrote two important papers on violations of Lorentz invariance. It was they (to the best of my knowledge) who pointed out the enormous value of Cerenkov radiation in testing Einstein’s relativity principles. (I’ve just written a new short article on Cerenkov radiation, and there I briefly explain how Coleman and Glashow used it previously to test Lorentz invariance.)

What Cohen and Glashow did last week was to generalize this idea to point out a new physical phenomenon (new at least to me) and use it to argue that OPERA’s result is self-inconsistent. They argue that the very effect of faster-than-light travel that OPERA claims to observe would have caused distortions in its neutrino beam that clearly were not observed. Moreover, Cohen and Glashow also pointed out that at least two other experiments studying higher energy neutrinos put even stronger constraints on the possibility of anything similar to what OPERA observed.

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