Quantum Newtonian dynamics on a light front - art. no. 025005

We recall the special features of quantum dynamics on a light front (in an infinite momentum frame) in string and field theory. The reason this approa ch is more effective for string than for fields is stressed: the light-fron t dynamics for string is that of a true Newtonian many particle system, sin ce a string bit has a fixed Newtonian mass. In contrast, each particle of a field theory has a variable Newtonian mass P+; so the Newtonian analogy ac tually requires an infinite number of species of elementary Newtonian parti cles. This complication substantially weakens the value of the Newtonian an alogy in applying light-front dynamics to nonperturbative problems. Motivat ed by the fact that conventional field theories can be obtained as infinite tension limits of string theories, we propose a way to recast field theory as a standard Newtonian system. We devise and analyze some simple quantum mechanical systems that display the essence of the proposal, and we discuss prospects for applying these ideas to large N-c QCD. [S0556-2821(99)01302- 8].