Stringy horizons and UV/IR mixing

Stringy Domain Walls and Other Stringy Topological Defects ⋆

We point out that the moduli sector of the (2, 2) string compactification with its nonperturbatively preserved non-compact symmetries is a framework to study global topological defects. Based on the target space modular invariance of the nonperturbative superpotential of the four-dimensional N = 1 supersymmetric string vacua, topologically stable stringy domain walls are found. Explicit supersy...

Strange and stringy.

Stringy Chern classes

Work of Dixon, Harvey, Vafa and Witten in the 80’s ([DHVW85]) introduced a notion of Euler characteristic (for quotients of a torus by a finite group) which became known as the physicist’s orbifold Euler number. In the 90’s V. Batyrev introduced a notion of stringy Euler number ([Bat99b]) for ‘arbitrary Kawamata log-terminal pairs’, proving that this number agrees with the physicist’s orbifold ...

Stringy Robinson-Trautman solutions.

A class of solutions of the low energy string theory in four dimensions is studied. This class admits a geodesic, shear-free null congruence which is non-twisting but in general diverging and the corresponding solutions in Einstein’s theory form the Robinson-Trautman family together with a subset of the Kundt’s class. The Robinson-Trautman conditions are found to be frame invariant in string th...

Stringy Toda Cosmologies

We discuss a particular stringy modular cosmology with two axion fields in seven space-time dimensions, decomposable as a time and two flat three-spaces. The effective equations of motion for the problem are those of the SU(3) Toda molecule, and hence are integrable. We write down the solutions, and show that all of them are singular. They can be thought of as a generalization of the Pre-Big-Ba...