Abstract :
Limits of a system of N Dn-branes in which the bulk and string degrees of freedom decouple to leave a ‘matter’ theory are investigated and, for n > 4, either give a free theory or require taking N → ∞. The decoupled matter theory is described at low energies by the N → ∞ limit of n + 1-dimensional super Yang-Mills, and at high energies by a free type II string theory in a curved space-time. Metastable bound states of D6-branes with mass M and D0-branes with mass m are shown to have an energy proportional to M13m23 and decouple, whereas in matrix theory they only decouple in the large N limit.
