Tuesday, November 22, 2011

Can The LHC Test For Superluminal Neutrinos?

That seems to be the case in a new paper that is about to be published. A new theoretical model by Davoudiasl and Rizzo based on the earlier one by Cohen and Glashow indicates that the LHC itself, using their existing detectors (probably ATLAS and CMS) might be able to detect signatures of superluminal neutrinos, if they exist.

Now, Hooman Davoudiasl of the Brookhaven National Laboratory in New York and Thomas Rizzo of SLAC National Laboratory in California have re-examined Glashow and Cohen's theory. True, the framework would open up neutrino decay in a vacuum, Davoudiasl and Rizzo say, but the OPERA neutrinos were travelling mostly through rock. Perhaps the rock stalls the decay for some reason – for example by making the neutrinos transform or "oscillate" into different types – which would mean Glashow and Cohen's theoretical framework would still be compatible with the OPERA result.

If so, then Glashow and Cohen's mechanism should turn up in other places – notably at the LHC, say Davoudiasl and Rizzo. Neutrinos are produced in the particle accelerator, for example when energetic top quarks decay, but they are not normally observed because they pass straight through the detectors. But if Glashow and Cohen's mechanism is at work, then some of the neutrinos should themselves decay, at roughly a metre from where they are produced. To someone studying the particle trails, this decay should manifest as an energetic electron–positron pair appearing suddenly, as if from nowhere. "This is a relatively easy signal to spot at the LHC," says Rizzo.
Easy? :)

In any case, I don't think this might be a convincing "evidence", whether such signals are detected or not. As stated in the article, the only convincing way to confirm or refute the OPERA results is for other long-baseline experiments, such as MINOS and T2K, to do the experiments. Until then, we will continue to go back and forth with model-dependent mechanism that will not be as convincing.


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