Decoupling limits in M-theory

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 M 1/3 m 2/3 and decouple, whereas in matrix theory they only decouple in the large N limit.fixed, giving the 't Hooft limit [24] of the super Yang-Mills theory, in which only the planar Feynman diagrams survive. In this limit, for large but finite N, the bulk and/or string modes do not decouple and are presumably crucial to the consistency of the theory, but in the infinite N limit, the bulk and string modes all

On domain-wall/QFT dualities in various dimensions

“…For instance, in some cases the worldvolume QFT involved in the DW/QFT duality is non-renormalizable. This indicates, for particular regions in the parameter space, the presence of extra non-decoupled degrees of freedom similar to those discussed in [22]. In this paper we discussed duality conjectures which can be related to delocalized Dpbrane intersections.…”

“…If we do not use the freedom to tune N, the analysis becomes more subtle because the bulk theory can become strongly coupled (g s → ∞). Sometimes this implies that the decoupling of gravity must be analysed in D + 1 dimensions and in some cases this decoupling is impossible [22]. This is, for instance, the case for all domain-wall p-branes and the D6-brane in D = 10.…”