Burt A. Ovrut — Page 8

arXiv1992

Natural Supergravity Inflation

We show that a single uncharged chiral superfield, canonically coupled to \mbox{$N=1$} supergravity with vanishing superpotential, naturally drives inflation in the early universe for a class of simple Kahler potentials. Inflation occurs due to the one-loop generation of a Kahler anomaly proportional to $\R^2$. The coefficient of this $\R^2$ term is of the correct magnitude to describe all aspects of an inflationary cosmology, including sufficient amplitude perturbations and reheating. Higher order terms proportional to $\R^n$ for $n \geq 3$ are naturally suppressed relative to the $\R^2$ term and, hence, do not destabilize the theory.

hep-th↗

arXiv1992

Coordinate and Kähler $σ$-Model Anomalies and Their Cancellation in String Effective Field Theories

We discuss the complete set of one-loop triangle graphs involving the Yang-Mills gauge connection, the \Kahler\ connection and the $σ$-model coordinate connection in the effective field theory of $(2,2)$ symmetric $Z_N$ orbifolds. That is, we discuss pure gauge, pure \Kahler\ and pure $σ$-model coordinate anomalies as well as the mixed anomalies, such as \Kahler-gauge, some of which have been discussed elsewhere. We propose a mechanism for restoring both \Kahler\ and $σ$-model coordinate symmetry based upon the introduction of two types of counterterms. Finally, we enlarge the $σ$-model generalization of the Green-Schwarz mechanism to allow the removal of the universal parts of a wider class of anomalies than those previously discussed.

hep-th↗