  We solve the quasiclassical problem of tunneling through an external
potential barrier in a dense plasma, where the tunneling particles undergo
simultaneous collisions with other particles in thermodynamic equilibrium.
Under such conditions the spectral density of states available to the particle
has a Lorentz shape, rather than the delta function, which leads to a quantum
tail in the particle momentum distribution function. We show that, this tail
indeed significantly alters the average nuclear reaction rates, which supports
earlier suggestions. This rate can be many orders of magnitude higher than
would be normally calculated by averaging over the Maxwell distribution of
energies.
