Keywords: Right left helicity zh.svg en It's convenient to quantize the spin of spin-1/2 particles along their direction of motion When the spin and the momentum are parallel the particle is called right-handed; when they are antiparallel the particle is left-handed These are known as helicity states Red arrows represent the spin; green arrows are the momentum Annotations are in Chinese 2011-08-17 Right left helicity svg 80 b l original jpg by en user HEL svg by Stannered chinese version by Choihei Other fields + clr Retouched picture translation Choihei Right left helicity svg HEL Uploaded with UploadWizard Spin intrinsic angular momentum |