  Employing a conformal map to hyperbolic space cross a circle, we compute the
universal contribution to the vacuum entanglement entropy (EE) across a sphere
in even-dimensional conformal field theory. Previous attempts to derive the EE
in this way were hindered by a lack of knowledge of the appropriate boundary
terms in the trace anomaly. In this paper we show that the universal part of
the EE can be treated as a purely boundary effect. As a byproduct of our
computation, we derive an explicit form for the A-type anomaly contribution to
the Wess-Zumino term for the trace anomaly, now including boundary terms. In
d=4 and 6, these boundary terms generalize earlier bulk actions derived in the
literature.

High Energy Physics - Theory