NO WORMHOLES WITH REAL MINIMALLY COUPLED SCALAR FIELDS - COMMENT

Cotsakis et al. [Phys. Rev. D 49, 6489 (1994)] claimed that wormhole s olutions can be obtained with real scalar fields which could in turn b e simulated with higher order gravity theories. Because of various sig n errors this conclusion is not justified, and instead a complex scala r field is necessary. Higher derivative theories can have wormholes by choosing the ''wrong signs'' for the coefficients in front of the fun ctions of scalar curvature. This ensures that there is a minus sign in front of the kinetic term in the conformally related scalar field the ory, thus ensuring that the Ricci tensor has negative eigenvalues. A r eal scalar field with a negative definite potential V(phi)<0, although satisfying the Ricci tensor condition, does not support a wormhole, a t least when using a FRW metric.