  We investigate large deviations of the free energy in the O'Connell-Yor
polymer through a variational representation of the positive real moment
Lyapunov exponents of the associated parabolic Anderson model. Our methods
yield an exact formula for all real moment Lyapunov exponents of the parabolic
Anderson model and a dual representation of the large deviation rate function
with normalization $n$ for the free energy.
