Joshua M. Lapan

\mathcal{N} = {1} sigma models in AdS4

A bstractWe study sigma models in AdS4 with global

String theory on warped AdS3 and Virasoro resonances

\mathcal{N} = {1}

Computing the Spectrum of a Heterotic Flux Vacuum

supersymmetry and find that they differ significantly from their flat-space cousins — the target space is constrained to be a Kähler manifold with an exact Kähler form, the superpotential transforms under Kähler transformations, the space of supersymmetric vacua is generically a set of isolated points even when the superpotential vanishes, and the R-symmetry is classically broken by the cosmological constant. Remarkably, the exactness of the Kähler class is also required for the sigma model to arise as a decoupling limit of

Collective field description of matrix cosmologies

\mathcal{N} = {1}

SUSY enhancements in (0, 4) deformations of AdS3/CFT2

supergravity, and ensures the vanishing of gravitational anomalies. As applications of these results, we argue that fields with AdS4 scale masses are ubiquitous in, for example, type IIB

Linear Models for Flux Vacua

\mathcal{N} = {1}

Nearing the Horizon of a Heterotic String

AdS4 vacua stabilized near large volume; we also present a schematic argument that the Affleck-Dine-Seiberg runaway of Nf  < Nc SQCD can be regulated by considering the theory in AdS4.

Towards the massless spectrum of non-Kähler heterotic compactifications

We investigate aspects of holographic duals to time-like warped AdS3 space-times — which include Gödel’s universe — in string theory. Using worldsheet techniques similar to those that have been applied to AdS3 backgrounds, we are able to identify space-time symmetry algebras that act on the dual boundary theory. In particular, we always find at least one Virasoro algebra with computable central charge. Interestingly, there exists a dense set of points in the moduli space of these models in which there is actually a second commuting Virasoro algebra, typically with different central charge than the first. We analyze the supersymmetry of the backgrounds, finding related enhancements, and comment on possible interpretations of these results. We also perform an asymptotic symmetry analysis at the level of supergravity, providing additional support for the world sheet analysis.

Falling d0-branes in 2-D superstring theory

We compute the massless spectra of a set of flux vacua of the heterotic string. The vacua we study include well-known non-Kähler T2-fibrations over K3 with SU(3) structure and intrinsic torsion. Following gauged linear sigma models of these vacua into phases governed by asymmetric Landau-Ginzburg orbifolds allows us to compute the spectrum using generalizations of familiar LG-orbifold techniques. We study several four- and six-dimensional examples with spacetime

Towards the Massless Spectrum of Non-Kähler Heterotic Compactifications

\mathcal{N} = 2