Details

An axial vector, also known as a pseudovector, occurs most often as the cross product of two polar vectors. An axial vector resembles a polar vector in some ways: although it reflects differently, it translates and rotates exactly like a polar vector.

In schematic diagrams we can use an arrow to denote an axial vector via the right-hand rule. This says to wrap your right hand around the rotating object with your fingers pointing in the direction of rotation and your thumb perpendicular to your fingers. The direction your thumb points is the direction we use for the arrow.

Reference

[1] S. L. Altmann, Icons and Symmetries, New York: Oxford University Press, 1992.