A no-ghost theorem for the bosonic Nappi-Witten string

Abstract

We prove a no-ghost theorem for a bosonic string propagating in Nappi-Witten spacetime. This is achieved in two steps. We first demonstrate unitarity for a class of NW/U(1) modules: the norm of any state which is primary with respect to a chosen timelike U(1) is non-negative. We then show that physical states - states satisfying the Virasoro constraints - in a class of modules of an affinisation of the Nappi-Witten algebra are contained in the NW/U(1) modules. Similar to the case of strings on $Ad{S}_3$, in order to saturate the spectrum obtained in light-cone quantization we are led to include modules with energy not bounded from below, which are related to modules with energy bounded from below by spectral flow automorphisms.

24 pages, 1 figure

References in corpus (19)

• Strings in flat space and pp waves from $\mathcal{N}=4$ Super Yang Mills
• Type IIB Green-Schwarz superstring in plane wave Ramond-Ramond background
• A new maximally supersymmetric background of IIB superstring theory
• Strings in AdS_3 and the SL(2,R) WZW Model. Part 1: The Spectrum
• A WZW model based on a non-semi-simple group
• Strings in AdS_3 and the SL(2,R) WZW Model. Part 3: Correlation Functions
• On solvable models of type IIB superstring in NS-NS and R-R plane wave backgrounds
• Geometrical interpretation of D-branes in gauged WZW models
• The No-ghost Theorem for AdS_3 and the Stringy Exclusion Principle
• String Propagation in Gravitational Wave Backgrounds
• Nonsemisimple Sugawara Constructions
• A Class of String Backgrounds as a Semiclassical Limit of WZW Models
• Gauging a Non-Semi-Simple WZW Model
• Cosets as gauge slices in SU(1,1) strings
• On Bosonic and Supersymmetric Current Algebras for Non-Semi-Simple Groups
• Exact string backgrounds from WZW models based on non-semi-simple groups
• Strings in Gravimagnetic Fields
• On the unitarity of gauged non-compact WZNW strings
• On the unitarity of gauged non-compact world-sheet supersymmetric WZNW models

Cited by in corpus (1)

• Modular invariant partition functions for non-compact G/Ad(H) models