A DUALITY BETWEEN STRINGS AND 5-BRANES

Not only does the heterotic string admit a heterotic 5-brane as a soliton but the heterotic 5-brane admits as a soliton a heterotic string. This provides further evidence that the two theories may be dual descriptions of the same physics, with the strong coupling regime of one theory described by the weak coupling regime of the other. To illustrate this, we show how the energy-momentum tensor of the quadratic Yang-Mills action associated with the string reduces to that of an elementary 5-brane, and how the energy-momentum tensor of the quartic Yang-Mills action associated with the 5-brane reduces to that of an elementary string.