Is it confirmed that the antiproton and antineutron exist on earth?

Answer 1

Yes, the antiproton and antineutron have both been confirmed. They were determined to exist in 1955 and 1956, respectively.

It should be noted that these particles are antimatter, and they don't just occur floating around in nature. There are nuclear reactions that occur on and around earth where the two particles are created, however. And they can be created in the physics lab with high enough energy accelerators.

Answer 2

Yes, antiprotons and antineutrons exist on Earth. They are antimatter counterparts to protons and neutrons, and are produced in high-energy particle accelerators. Their existence and properties have been confirmed through experiments in particle physics.