Physics:Scaling variable

One calls a scaling variable any variable allowing one to find an identical description of phenomena in different situations by expressing them in a suitable projection. Examples are the description of electromagnetic interactions in matter in terms of L/X₀ where X₀ is the radiation length, the probability distribution of multiplicities of produced particles which scales approximately if plotted in terms of ( KNO-distribution), and in particular the scaling variables in inclusive reactions ( Deep Inelastic Scattering Variables).

Deviations from exact scaling are called scaling violations.