  We study the dynamics of denaturation bubbles in double-stranded DNA on the
basis of the Poland-Scheraga model. We demonstrate that the associated
Fokker-Planck equation is equivalent to a Coulomb problem. Below the melting
temperature the bubble lifetime is associated with the continuum of scattering
states of the repulsive Coulomb potential, at the melting temperature the
Coulomb potential vanishes and the underlying first exit dynamics exhibits a
long time power law tail, above the melting temperature, corresponding to an
attractive Coulomb potential, the long time dynamics is controlled by the
lowest bound state. Correlations and finite size effects are discussed.
