Formation time scaling and hadronization in cold nuclear matter

I propose a scaling analysis of the hadron multiplicity ratio measured in Deep Inelastic Scattering on nuclear targets as a tool to distinguish energy loss and nuclear absorption effects on hadron suppression in cold nuclear matter. The proposed scaling variable is a function of the hadron fractional energy and of the virtual photon energy. Its functional form, which depends on a parameter λ, can be fixed by general theoretical considerations and encompasses both energy loss and absorption models. The parameter λ is fitted to HERMES experimental data and shown to favor prehadron nuclear absorption as leading mechanism for hadron suppression as opposed to quark energy loss.