  Constraints on the tension and the abundance of cosmic strings depend
crucially on the rate at which they decay into particles and gravitational
radiation. We study the decay of cosmic string loops in the Abelian-Higgs model
by performing field theory simulations of loop formation and evolution. We find
that our set of string loops emit particle radiation primarily due to kink
collisions, and that their decay time due to these losses is proportional to
$L^p$ with $p \approx 2$ where $L$ is the loop length. In contrast, the decay
time to gravitational radiation scales in proportion to $L$, and we conclude
that particle emission is the primary energy loss mechanism for loops smaller
than a critical length scale, while gravitational losses dominate for larger
loops.
