  The nucleon energy-energy correlator (NEEC) was proposed in 2209.02080 as a
new way of studying nucleon intrinsic dynamics. In this work, we present a
detailed derivation of the factorization theorem that enables the measurement
of the unpolarized NEEC in lepton-ion collisions. As a first step towards a
precise measurement of this quantity, we obtained the
next-to-leading-logarithmic (NLL, $\sim{\cal O}(\alpha_s^n L^{n-1})$)
resummation in a concise analytic form, and predicted the analytic
$\theta$-angle distribution at ${\cal O}(\alpha^2_s)$. Extending our analytic
resummation formula to higher logarithmic accuracy and the factorization
theorem to hadron-hadron collisions is straightforward.
