Acoustic spin and orbital angular momentum using evanescent Bessel beams

Using acoustic evanescent Bessel beam is analyzed the fundamental properties for the spin and orbital angular momentum. The calculation shows that the transversal spin, the canonical momentum, and the orbital angular momentum are proportional to the ratio $l/\omega$, where $l$ is the topological charge and $\omega$ the angular frequency. The complex acoustic Poynting vector and spin density exhibit interesting features related to the electromagnetic case.