  Decay law of a complicated unstable state formed in a high energy collision
is described by the Fourier transform of the two-point correlation function of
the scattering matrix. Although each constituent resonance state decays
exponentially the decay of a state composed of a large number of such
interfering resonances is not, generally, exponential. We introduce the decay
rates distribution function by representing the decay law in the form of the
mean-weighted decay exponent. In the framework of the random matrix approach we
investigate the properties of the new distribution function and its relation to
the more conventional statistics of the decay widths. The latter is not in fact
conclusive as concerns the evolution during the time shorter than the
characteristic Heisenberg time. Exact analytical consideration is presented for
the case of systems without time reversal symmetry.
