Simple parameterization of nuclear attenuation data

Based on the semi-inclusive deep inelastic scattering data obtained by the HERMES experiment on deuterium, nitrogen and krypton nuclei, it is shown that a ratio of multiplicities on nucleus and deuterium (per nucleon) for given hadron R-M(h) can be parametrized in a form of a linear polynomial a(11)+tau a(12), where tau is the formation time, which depends on the energy of the virtual photon nu and fraction of that energy z carried by the final hadron. Three widely known parametrizations for tau were used for the performed fit. The fit parameters a(11) and a(12) do not depend on nu and z.