1. A quantum number assigned to subatomic particles (such as nucleons and pions) that describes their behavior under the strong nuclear force, treating particles with similar properties but different electric charges as different states of the same particle.
Usage: physics; technical term used in nuclear and particle physics

Examples

• The proton and neutron are considered two states of the same nucleon with different isospin values.
• Isospin symmetry helps physicists understand why certain particle interactions occur and others do not.
• In the standard model, isospin is a fundamental quantum number that characterizes hadrons.
• The conservation of isospin in strong interactions explains the relative abundances of different particle decay modes.
• Physicists use isospin to classify particles into multiplets based on their charge and mass properties.