Washington: A new discovery by scientists provides a crucial key to understanding how neutrinos, ghostly particles with multiple personalities, change identity and may help shed light on why matter exists in the universe.
Members of the large international Daya Bay collaboration reported the last of three measurements that describe how the three types, or flavours, of neutrinos blend with one another, providing an explanation for their spooky morphing from one flavour to another, a phenomenon called neutrino oscillation.
The inside of a cylindrical antineutrino detector before being filled with clear liquid scintillator, which reveals antineutrino interactions by the very faint flashes of light they emit. Sensitive photomultiplier tubes line the detector walls, ready to amplify and record the telltale flashes.
The measurement makes possible new experiments that may help explain why the present universe is filled mostly with matter, and not equal parts of matter and antimatter that would have annihilated each other to leave behind nothing but energy.
One theory is that a process shortly after the birth of the universe led to the asymmetry, but a necessary condition for this is the violation of charge-parity (or CP) symmetry. If neutrinos and their antimatter equivalent, antineutrinos, oscillate differently, this could provide the explanation.
“The result is very exciting, because it essentially allows us to compare neutrino and antineutrino oscillations in the future and see how different they are and hopefully have an answer to the question, Why do we exist?” Kam-Biu Luk, co-spokesperson of the experiment from the University of California, Berkeley, said.
Researchers knew that if the observed third kind of oscillation were zero or near zero, it would make further study of matter-antimatter asymmetry difficult.
“This is a new type of neutrino oscillation, and it is surprisingly large,” Yifang Wang, co-spokesperson and Chinese project manager of the Daya Bay experiment, said.
“Our precise measurement will complete the understanding of the neutrino oscillation and pave the way for the future understanding of matter-antimatter asymmetry in the universe,” Wang added.
The study has been submitted to the journal Physical Review Letters.