Asymptotic freedom and infrared behavior in the type 0 string approach to gauge theory

In a recent paper we considered the type 0 string theories, obtained from t he ten-dimensional closed NSR string by a GSO projection which excludes spa ce-time fermions, and studied the low-energy dynamics of N coincident D-bra nes, This led us to conjecture that the four-dimensional SU(N) gauge theory coupled to six adjoint massless scalars is dual to a background of type 0 theory carrying N units of R-R 5-form flux and involving a tachyon condensa te. The tachyon background leads to a "soft breaking" of conformal invarian ce, and we derived the corresponding renormalization group equation. Minaha n has subsequently found its asymptotic solution for weak coupling and show ed that the coupling exhibits logarithmic flow, as expected from the asympt otic freedom of the dual gauge theory, We study this solution in more detai l and identify the effect of the 2-loop beta function. We also demonstrate the existence of a fixed point at infinite coupling, Just like the fixed po int at zero coupling, it is characterized by the AdS(5) x S-5 Einstein fram e metric. We argue that there is a RG trajectory extending all the way from the zero coupling fixed point in the UV to the infinite coupling fixed poi nt in the IR. (C) 1999 Elsevier Science B.V.