![Explained | Are neutrinos their own antiparticles?
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Explained | Are neutrinos their own antiparticles? Premium
The Hindu
The answer to this question has profound implications for a mystery about the universe.
Neutrinos are the second most abundant particles in the cosmos, produced in copious amounts in the cores of stars. Because they are so ubiquitous, their properties are windows into the microscopic structure of the universe.
For example, one open question about neutrinos is whether they are their own antiparticles. If they were, physicists will have a way to explain why the universe has more matter than antimatter.
But an experiment in Japan recently reported that it failed to find “strong evidence” that this is the case, ruling out some – but not all – theories.
What are anti-particles?
Every elementary particle has an anti-particle. If the two meet, they will destroy each other in a flash of energy.
The electron’s anti-particle is the positron. Similarly, neutrinos have anti-neutrinos. However, an electron is distinguishable from a positron because they have opposite charges. Neither neutrinos nor anti-neutrinos have electric charge, nor any other properties to really differentiate between them.
One way to classify subatomic particles is as matter particles and force-carrying particles. Neutrinos are matter particles, or fermions. Fermions can be further split as Dirac fermions or Majorana fermions. Dirac fermions are not their own anti-particles, whereas Majorana fermions are.