BPS DYNAMICS OF THE TRIPLE (P,Q) STRING JUNCTION

We study the dynamics of the triple junction of (p, q) strings in Type IIB string theory. We probe the tension and mass density of (p, q) st rings by studying harmonic fluctuations of the triple junction. We sho w that they agree perfectly with the BPS formula provided a suitable g eometric interpretation of the junction is given. We provide a precise statement of the BPS limit and force-balance property. At weak coupli ng and sufficiently dense limit, we argue that a (p, q) string embedde d in the string network is a 'wiggly string', whose low-energy dynamic s can be described via a renormalization group evolved, smooth effecti ve non-relativistic string. We also suggest the possibility that, upon Type IIB strings being promoted to the M-theory membrane, there can e xist 'evanescent' bound-states at the triple junction in the continuum . (C) 1998 Elsevier Science B.V.