  We study the transport mechanisms taking place in a quantum spin Hall bar
with an embedded quantum dot, where electrons localize and experience Coulomb
interaction U as well as spin-flip processes {\lambda}. We solve the problem
with non-equilibrium Green functions. We focus on the linear response regime
and treat the many-body interactions with quantum Monte Carlo. The effects of U
and {\lambda} are competitive and the induced transport takes place through
different channels. The two mechanisms can be switched by changing the
occupation of the dot with a gate voltage.
