The exponential of the spin representation of the Lorentz algebra    [PDF]

Jason Hanson
As discussed in a previous article, any (real) Lorentz algebra element
possess a unique orthogonal decomposition as a sum of two mutually annihilating
decomposable Lorentz algebra elements. In this article, this concept is
extended to the spin representation of the Lorentz algebra. As an application,
a formula for the exponential of the spin representation is obtained, as well
as a formula for the spin representation of a proper orthochronous Lorentz
transformation.
View original: http://arxiv.org/abs/1201.6047