Non-supersymmetric D-branes with vanishing cylinder amplitudes in asymmetric orbifolds

Abstract

Abstract We study the type II string vacua with chiral space-time SUSY constructed as asymmetric orbifolds of torus and K3 compactifications. Despite the fact that all the D-branes are non-BPS in any chiral SUSY vacua, we show that the relevant non-geometric vacua of asymmetric orbifolds allow rather generally configurations of D-branes which lead to vanishing cylinder amplitudes, implying the bose-fermi cancellation at each mass level of the open string spectrum. After working on simple models of toroidal asymmetric orbifolds, we focus on the asymmetric orbifolds of T 2 × ℳ, where ℳ is described by a general N $$ \mathcal{N} $$ = 4 SCFT with c = 6 defined by the Gepner construction for K3. Even when the modular invariant partition functions in the bulk remain unchanged, the spectra of such non-BPS D-branes with the bose-fermi cancellation can vary significantly according to the choice of orbifolding.

Keywords

• Conformal Field Models in String Theory
• D-branes
• Superstring Vacua
• Superstrings and Heterotic Strings