Antineutron

The antineutron is the neutron’s antimatter counterpart, with the same mass and zero electric charge but opposite baryon number. It is composed of antiquarks and annihilates with matter.

Neutron: A neutral baryon composed of one up quark and two down quarks. It has the antineutron’s mass and charge, but opposite quark content and baryon number.
Matter–antimatter annihilation: A process in which a particle and its antiparticle convert their rest energy into other particles. An antineutron can annihilate with a neutron or other matter despite having no electric charge.
Antimatter: Matter composed of antiparticles with opposite additive quantum numbers to corresponding particles. The antineutron is a neutral member of this class.
Baryon number violation: A process in which the total baryon number changes, contrary to its conservation in ordinary observed reactions. Neutron–antineutron oscillation would be a direct example.
Antiquark: An elementary antiparticle corresponding to a quark, with opposite additive charges. Three antiquarks make up an antineutron.
Neutron–antineutron oscillation: A hypothetical transition in which a neutron spontaneously becomes an antineutron. This proposed process would change baryon number and test whether neutrons and antineutrons can transform into each other.
Bruce Cork: An American experimental physicist who co-discovered the antiproton at Berkeley in 1955. His antiproton discovery helped establish the experimental search for other antiparticles.
Baryogenesis: The set of proposed processes that produced the universe’s excess of matter over antimatter. Baryon-number-changing processes involving neutrons could illuminate how that excess arose.
Baryon number: A conserved quantum number that assigns baryons value +1 and antibaryons value −1. Its sign distinguishes the antineutron from the neutron despite both being electrically neutral.
Strong interaction: The fundamental interaction that binds quarks into hadrons and acts between hadrons. It governs antineutron interactions with nuclei and contributes to annihilation after capture.

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AntiparticleBroader topic: It shows that an antiparticle can be electrically neutral yet differ in other quantum numbers.