helicity

noun plural -ties

physics the projection of the spin of an elementary particle on the direction of propagation

Word Origin for helicity

C20: from helix + -ity

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helicity in Science

helicity

[hə-lĭs′ĭ-tē, hē′]

The projection of a particle's spin vector in the direction of its momentum vector, being positive if it points in the same direction, and negative if it points in the opposite direction. Helicity is in effect the handedness, or chirality, of the spin of a particle.