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posted by janrinok on Tuesday August 09 2016, @02:26AM   Printer-friendly
from the is-you-is-or-is-you-ain't? dept.

Evidence mounts that neutrinos are the key to the universe's existence.

New experimental results show a difference in the way neutrinos and antineutrinos behave, which could explain why matter persists over antimatter.

The results, from the T2K experiment in Japan, show that the degree to which neutrinos change their type differs from their antineutrino counterparts. This is important because if all types of matter and antimatter behave the same way, they should have obliterated each other shortly after the Big Bang.

So far, when scientists have looked at matter-antimatter pairs of particles, no differences have been large enough to explain why the universe is made up of matter — and exists — rather than being annihilated by antimatter. Neutrinos and antineutrinos are one of the last matter-antimatter pairs to be investigated since they are difficult to produce and measure, but their strange behaviour hints that they could be the key to the mystery.

Neutrinos (and antineutrinos) come in three 'flavours' of tau, muon and electron, each of which can spontaneously change into the other as the neutrinos travel over long distances. The latest results, announced today by a team of researchers including physicists from Imperial College London, show more muon neutrinos changing into electron neutrinos than muon antineutrinos changing into electron antineutrinos.

This difference in muon-to-electron changing behaviour between neutrinos and antineutrinos means they would have different properties, which could have prevented them from destroying each other and allow the universe to exist.

[...] The latest results were concluded from relatively few data points, meaning there is still a one in 20 chance that the results are due to random chance, rather than a true difference in behaviour. However, the result is still exciting for the scientists involved.

Dr Morgan Wascko, international co-spokesperson for the T2K experiment from the Department of Physics at Imperial said: "This is an important first step towards potentially solving one of the biggest mysteries in science. T2K is the first experiment that is able to study neutrino and antineutrino oscillation under the same conditions, and the disparity we have observed is, while not yet statistically significant, very intriguing."

The results were presented at the 38th International Conference on High Energy Physics in Chicago. More detailed information is available at the T2K website and in the presentation (pdf).


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  • (Score: 0) by Anonymous Coward on Tuesday August 09 2016, @09:08AM

    by Anonymous Coward on Tuesday August 09 2016, @09:08AM (#385695)

    Looks like there is no sterile neutrino from ice cube detector http://arstechnica.com/science/2016/08/antarticas-icecube-turns-up-no-evidence-of-sterile-neutrinos/ [arstechnica.com]
    Or maybe these is good news as well, just can't tell with those shifty neutrinos

  • (Score: 4, Interesting) by maxwell demon on Tuesday August 09 2016, @01:06PM

    by maxwell demon (1608) on Tuesday August 09 2016, @01:06PM (#385743) Journal

    I'm not a particle physicist, but what I've always wondered:

    It is said there are only left-handed neutrinos.

    However look at how a right handed neutrino should behave:

    • It is a lepton, therefore it doesn't interact with the strong force.
    • It is uncharged, therefore it doesn't interact with the electromagnetic force.
    • It is a right-handed lepton, therefore it doesn't interact with the weak force.

    Or in short, a right-handed neutrino would necessarily be a sterile neutrino. And AFAIU neutrino oscillations don't change the handedness, therefore the right-handed neutrinos would only oscillate into other right-handed neutrinos, which are just as sterile. Or in short, it would not be a surprise that we can't see them, as they only would interact with gravitation.

    So maybe there's a particle physicist here who can tell me what's wrong with right-handed neutrinos, so we assume they don't exist?

    --
    The Tao of math: The numbers you can count are not the real numbers.
    • (Score: 2) by Taibhsear on Tuesday August 09 2016, @03:54PM

      by Taibhsear (1464) on Tuesday August 09 2016, @03:54PM (#385806)

      Or in short, it would not be a surprise that we can't see them, as they only would interact with gravitation.

      Which would make them dark matter, yes?

      • (Score: 2) by maxwell demon on Tuesday August 09 2016, @04:38PM

        by maxwell demon (1608) on Tuesday August 09 2016, @04:38PM (#385832) Journal

        Yes. However, as the mass of left-handed neutrinos is not sufficient to explain the observed dark matter, probably the right handed neutrinos wouldn't be either. On the other hand, it probably would be hard to tell how many right-handed neutrinos are there, as they probably would have had to be produced very early in the universe, when gravitation was strong enough to significantly produce them (they would also be in the Hawking radiation of black holes, but that would only add a negligible amount of mass).

        --
        The Tao of math: The numbers you can count are not the real numbers.