Schwinger-Dyson equation and confinement in quantum chromodynamics

A method to investigate the infrared behavior of the gluon propagator in Quantum Chromodynamics is suggested. We use Schwinger-Dyson equation for the gluon propagator involving proper vertices. Based on Ward-Takahashi identities we approximate these vertices to obtain a nonlinear integral equation determining the infrared behavior of the gluon propagator. We examine two possible solutions to this equation which are of interest to confinement of quarks. One corresponds to that of an infrared singular propagator which can generate long range forces between colored objects. The second to that of very massive gluons. Finally we make a brief speculation on color singlets