half-integer

noun

plural half-integers

: any number of the form x/2, where x is any odd integer

Particles whose spin is a half-integer of h, on the other hand, are fermions satisfying the Pauli exclusion principle; no two particles can have the same state.

—Qimiao Si et al., Science, 3 Sept. 2010

Note: A half of an even integer is considered an integer. A half-integer is the result of a half of an odd integer.

half-integral adjective

All the particles that we like to think of as “real” particles, like protons, neutrons and electrons, have spin which is half-integral—1/2, 3/2, 5/2 and so on.

—John Gribbin, The Search For Superstrings, 1998

Word History

First Known Use

1897, in the meaning defined above

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