  We present conditions for a family
$\left(A\left(x\right)\right)_{x\in\mathbb{R}^{d}}$ of self-adjoint operators
in $H^{r}=\mathbb{C}^{r}\otimes H$ for a separable complex Hilbert space $H$,
such that the Callias operator $D=ic\nabla+A\left(X\right)$ satisfies that
$\left(D^{\ast}D+1\right)^{-N}-\left(DD^{\ast}+1\right)^{-N}$ is trace class in
$L^2\left(\mathbb{R}^{d},H^{r}\right)$. Here, $c\nabla$ is the Dirac operator
associated to a Clifford multiplication $c$ of rank $r$ on $\mathbb{R}^{d}$,
and $A\left(X\right)$ is fibre-wise multiplication with $A\left(x\right)$ in
$L^2\left(\mathbb{R}^{d},H^{r}\right)$.
