  In 2008, Lehner, Wettig, Guhr and Wei conjectured a power series identity and
showed that it implied a determinantal formula for a Bessel-type integral over
the unitary supergroup. The integral is the supersymmetric extension of
Bessel-type integrals over the unitary group appearing as partition functions
in quantum chromodynamics. The identity is proved by interpreting both sides as
the same unitary integral, which can be computed using the Cartan
decomposition. An equivalent identity of Schur functions is also given and
interpreted probabilistically.
