Approximation method for the nuclear structure functions at small $x$

We have shown that the relationship between the DIS structure functions is stable for a nuclear target with mass number A at $x\le {10}^{-3}$. Numerical results are provided for the specific nuclei 12C and 208Pb using the nuclear PDF parameterizations implemented in the HIJING2.0 model. These results fall whithin the EIC kinematic acceptance for heavy ion running. The ratio $R_{F_L}^A$ is calculated as the ratio $R_{F_2}^A$ in the HIJING2.0 model.