document: One of the challenges in quantum chromodynamics (QCD) is the relativistic bound state problem. In the light-cone Hamiltonian approach [1] light-cone wave functions can be constructed in a boost invariant way. It is necessary to have reliable light-cone wave functions if one wants to calculate high energy scattering, especially exclusive reactions. Many parametrizations assume separability of the dependence on the longitudinal momentum fraction and transverse momentum which is very unlikely since the two momenta are coupled in the kinetic energy operator. Various approaches have been tried to compute such wave functions. One can use the usual equal time Hamiltonian [2] and transform the resulting wave functions into light-cone form with the help of kinematical on-shell equations. The light-cone Hamiltonian in a string picture is formulated in Ref. [3]. More ambitious is the construction of an effective Hamiltonian including the gauge degrees of freedom explicitly and then solving the bound state problem. For mesons this approach [4,5] still needs many parameters to be fixed. Attempts have been made to solve the valence quark wave function for mesons in a simple Hamiltonian with a two-body potential [6].
doc_bio_tags: O O O O O B I B O O B I I I O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O B I I I O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O B I I I I I I I I I I I O O B I I I I O B O O O O O O O O O O O O O O O O O B I I I O B O O O B O O O O O
extractive_keyphrases: calculate high energy scattering construction of an effective hamiltonian including the gauge degrees of freedom explicitly equal time hamiltonian hamiltonian mesons qcd quantum chromodynamics reactions relativistic bound state problem solving the bound state problem valence quark wave function
abstractive_keyphrases: kinematical on-shell equations light-cone hamiltonian approach light-cone wave functions reliable light-cone wave functions simple hamiltonian with a two-body potential solve the valence quark wave function for mesons transform the resulting wave functions into light-cone form