of the experimental data arising from both the theoretical progress and the growth of computational capacity. On the other hand, QCD at high energy is most conveniently expressed through the light-front variables [@Lepage:1980fj]. While the so-called “hard processes” may be evaluated through perturbation theory (pQCD), non-perturbative information from QCD is also needed and is encoded within the so-called “light-cone distributions”. The light-cone distributions are intrinsically *Minkowskian*, and cannot be easily extracted from a Euclidean formulation of quantum field theories. It is anticipated that the light-front[^1] Hamiltonian formalism provides a complementary alternative to lattice gauge theory [@Bakker:2013cea], with convenient access to light-cone distributions and other observables.

In principle, the hadron mass spectrum and light-front wave functions (LFWFs) can be obtained from diagonalizing the light-front quantized QCD (LFQCD) Hamiltonian operator [@Brodsky:1997de]. Ab initio light-front Hamiltonian approaches, such as Discretized Light-Cone Quantization (DLCQ, [@Pauli:1985ps]) and Basis Light-Front Quantization (BLFQ, [@Vary:2009gt]), have made important strides in tackling various test problems, and show promise of advancing towards more realistic field theories, including QCD [@Vary:2016emi]. As a complementary method to these ab initio approaches, light-front holography constructs an effective Hamiltonian based on insights from string theory, and has been shown, notwithstanding criticisms (e.g., [@Ballon-Bayona:2014oma; @Glozman:2009bt]), to 