NEUTRINOS can switch between flavours more rapidly than expected. The result means we could soon learn why the universe is filled with matter instead of featureless radiation.
The three flavours of neutrino - electron, muon and tau - morph into one another. This shape-shifting ability is measured by three parameters: theta12, theta23 and theta13. The first two have been measured precisely, but we only had an estimate for theta13.
Now researchers at the Daya Bay Reactor Neutrino Experiment in southern China (pictured) have seen electron antineutrinos transforming into muon antineutrinos at a rapid rate, which pins down the last parameter (arxiv.org/abs/1203.1669). "It's not as small as first thought," says Kam-Biu Luk, co-spokesperson for the experiment.
The high value means physicists can build experiments to find out whether neutrinos behave differently from antineutrinos - which would have been difficult had theta13 been small. Such experiments could provide clues to why the universe had a preference for matter over antimatter in the moments after the big bang.
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