Jones polynomials from matrix elements of tangles in a pseudounitary representation

Abstract

In these notes we review the calculation of Jones polynomials using a matrix representation of the braid group and Temperley-Lieb algebra. The pseudounitary representation that we consider allows constructing ``states'' from the group/algebra matrices and compute the knot invariants as matrix elements, rather than traces. In comparison with a more standard way of computing the invariants through traces, the matrix element method is more interesting and complete from the point of view of applications. As a byproduct of the discussion we prove a general formula for pretzel knots.

lecture notes, 9 pages, some typos fixed and some references added in this version