Accidental $\xi$-scaling as a Signature of Nuclear Effects at $x>1$

Abstract

We propose an interpretation of the $\xi$-scaling behavior of nuclear structure functions observed at Bjorken $x>1$ and $Q^2 \lesssim 4 \, {\rm (GeV/c)^2}$. We show that at $\xi \gtrsim 1$, $\xi$-scaling might arise accidentally because of the approximate cancellation of two different $Q^2$-dependent effects, namely Final State Interactions and the effects implicit in the choice of the scaling variable $\xi$. We provide a new convolution formula for the nuclear structure function in terms of $\xi$ and make predictions for the kinematical regions where Final State Interactions are expected to be small and the suggested balancing of scaling violations is expected to break down. Our analysis is aimed at the final goal of clarifying the range of applicability of local duality ideas in nuclei.