spaceSpace and Physics

Neutrino Beam Experiment Could Explain A Fundamental Problem With The Universe


Dr. Alfredo Carpineti

Senior Staff Writer & Space Correspondent

clockJul 13 2016, 20:50 UTC
Kamioka Observatory, ICRR (Institute for Cosmic Ray Research),The University of Tokyo.

Why is the universe made of matter instead of anti-matter? This question, which might seem trivial at first, has kept physicists busy for many decades, but we are slowly getting an answer.

According to the Standard Model of Particle Physics, the theory of fundamental physics, matter, and anti-matter are perfectly mirrored, so there must be mechanisms that give matter an advantage.


Now, Japanese researchers might have found one of these mechanisms. According to preliminary results from the Tokai to Kamioka (T2K) neutrino experiment, neutrino oscillation happens more often than anti-neutrino oscillation, which could have played a big role in matter dominance after the Big Bang.

Neutrinos are tiny fundamental particles with no charge that are produced in nuclear reactions. Every second, a constant stream of trillions of neutrinos coming from the Sun pass through your body. There are three types, or "flavors", of neutrinos (electron, muon, tau), and neutrinos oscillate between these three.

The T2K experiment detects these oscillations by shooting a neutrino beam from a research center in Tokai to the Super-Kamiokande neutrino detector 295 kilometers (183 miles) away.


Hirohisa Tanaka of the University of Toronto, Canada, reported the latest results from T2K at the 27th International Conference on Neutrino Physics and Astrophysics (Neutrino 2016). The experiment detected 32 muon neutrinos turning into electron neutrinos, compared to only four muon anti-neutrinos becoming electron anti-neutrinos.

This finding is definitely interesting, but it is too soon to throw our physics book out of the window. The detection has a confidence level of two sigmas, which is saying that they would see such a difference once every 20 times the experiment is repeated.

The golden standard for a physics discovery is five sigma, which reduces the chance that the observation is a fluke to one in 3.5 million.


If the research is confirmed, this could be an interesting violation of a fundamental symmetry of physics called CP, which stands for Charge and Parity. The charge symmetry requires that if we switch every particle for its antiparticle, and mirrored the set up of the space, physics is expected to behave in the same way. Recently, another interesting violation of CP was observed with the discovery of a new pear-shaped atom.

We are aware that there’s physics beyond the Standard Model, and maybe we are close to finding out what that is.

[H/T: New Scientist]

spaceSpace and Physics
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  • neutrino,

  • antineutrino,

  • neutrino oscillation,

  • CP symmetry