  In this proceeding we determine the distribution amplitude of the
$\eta_c$-meson from first principles. This quantity appears as a consequence of
factorization theorems, and it is necessary to compute the amplitude of
multiple exclusive processes. Since it is defined along a light-cone, its
calculation via lattice QCD was impossible until recently, when a
generalization to Euclidean metric was proposed, and a connection to the
physical limit was established. We briefly explain the method of short distance
factorization, which allows us to compute the distribution amplitude, and our
lattice setup. After summarizing the steps for the continuum and chiral
extrapolation, we present our results and compare them to two alternative
determinations, one using non-relativistic QCD and another solving the
Dyson-Schwinger equations; we find a large discrepancy with the former.
