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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).
(Score: 4, Informative) by number6x on Tuesday August 09 2016, @03:44PM
This research seem to show that the rate at which muon neutrinos turn into electron neutrinos is different than the rate at which muon anti-neutrinos turn into electron anti-neutrinos.
This difference in behaviour between a particle and it's anti particle may be a key in understanding why our universe is dominated by matter, and not anti-matter.
As a neutrino travels long distances through space it can phase between the various neutrino type; from muon to electron, from electron to tau, from tau to muon and so on. Neutrinos have several eigenstates, corresponding to the three normal matter types and the three antimatter types. an actual neutrino, in the wild, is a super-position of the these eigenstates. As it travels along, if it is measured at any one time, it may be caught in it's original state, or in one of the two others.
if the universe started out with the same number of each flavour and the same number of each anti-flavour, they could always annihilate each other. If they each phased through the various flavour of muon, electron and tau at the same rate there would always be the same number of each. However, if there was a difference in the rates for phases for neutrino and anti-neutrino, there could be an excess of one type over another. This could lead to a preponderance of matter over anti-matter.
Neutrinos are neutral, not carrying a charge, but it is unknown if they are Majorana particles [wikipedia.org]. A Majorana particle is it's own anti-particle. A neutron and anti-neutron are also without charge, but are composed of either quarks or anti-quarks. A neutron is not its own anti-particle, although both have no charge. Neutrinos are leptons and are not composed of quarks.
Do note that the article says this observation is based on very few data points. Doing neutrino measurement studies takes patience as the little buggers do not like to interact with everything else.