Neutrinos hint of matter-antimatter rift

Discussion in 'Physics & Math' started by Plazma Inferno!, Aug 1, 2016.

  1. Plazma Inferno! Ding Ding Ding Ding Administrator

    In the same underground observatory in Japan where, 18 years ago, neutrinos were first seen oscillating from one “flavor” to another — a landmark discovery that earned two physicists the 2015 Nobel Prize — a tiny anomaly, detected by the T2K experiment, has begun to surface in the neutrinos’ oscillations that could herald an answer to one of the biggest mysteries in physics: why matter dominates over antimatter in the universe.
    Many physicists suspect that the answer lies with neutrinos — ultra-elusive, omnipresent particles that pass unfelt through your body by the trillions each second.
    Experts overwhelmingly favor a double-duty explanation of neutrino mass and single-handedness called the “seesaw mechanism,” whereby the known, lightweight, left-handed neutrinos have much heavier right-handed counterparts, and the known antineutrinos likewise have superheavy left-handed counterparts (the light and heavy masses are inversely related, like two sides of a seesaw). For this seesaw explanation to work, the neutrinos and antineutrinos on each side of the seesaw must actually be the same particle, except for their opposite handedness. Numerous experiments are now hunting for an extremely rare radioactive decay that would confirm this “Majorana” nature of neutrinos, thereby shoring up the logic of the seesaw mechanism.
    If the theory is correct, then the heavy neutrinos and antineutrinos would have populated the hot young universe, when there was enough energy to beget beastly particles. They would have since decayed. Physicists wonder: Might their decays have produced the matter-antimatter asymmetry? This is the question to which an answer may be emerging — and much sooner than expected.
    danshawen likes this.

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