A permanental field, $\psi=\{\psi(\nu),\nu\in {\mathcal{V}}\}$, is a
particular stochastic process indexed by a space of measures on a set $S$. It
is determined by a kernel $u(x,y)$, $x,y\in S$, that need not be symmetric and
is allowed to be infinite on the diagonal. We show that these fields exist when
$u(x,y)$ is a potential density of a transient Markov process $X$ in $S$. A
permanental field $\psi$ can be realized as the limit of a renormalized sum of
continuous additive functionals determined by a loop soup of $X$, which we
carefully construct. A Dynkin-type isomorphism theorem is obtained that relates
$\psi$ to continuous additive functionals of $X$ (continuous in $t$),
$L=\{L_t^{\nu},(\nu ,t)\in {\mathcal{V}}\times R_+\}$. Sufficient conditions
are obtained for the continuity of $L$ on ${\mathcal{V}}\times R_+$. The metric
on ${\mathcal{V}}$ is given by a proper norm.Comment: Published in at http://dx.doi.org/10.1214/13-AOP893 the Annals of
Probability (http://www.imstat.org/aop/) by the Institute of Mathematical
Statistics (http://www.imstat.org