ABSTRACT
We study the theory of the https://www.w3.org/1998/Math/MathML"> ( 1 / 2,0 ) ⊕ ( 0,1 / 2 ) https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429076619/c00d8d0d-b3a0-431a-a3c2-e044ea15f7a5/content/eq3924.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/> and https://www.w3.org/1998/Math/MathML"> ( 1,0 ) ⊕ ( 0,1 ) https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429076619/c00d8d0d-b3a0-431a-a3c2-e044ea15f7a5/content/eq3925.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/> representations of the Lorentz group in the helicity basis. The helicity eigenstates are not the parity eigenstates. This is in accordance with the idea of Berestetskiū, Lifshitz and Pitaevskiǔ. The properties of the helicity eigenstates with respect to the charge conjugation and the CP - conjugation are also considered.
