The Lorentzian Space-Times of the Orientation-Orbifold String Systems

الأصل · EN

To illustrate our recent discussions of the target space-times in general orbifold-string theories of permutation-type, we return here to a detailed analysis of some simple examples of this type, namely an explicit set of orientation-orbifold string systems. These orientation-orbifold string systems provide twisted, multisector generalizations of ordinary critical open-closed bosonic string systems -- each such system exhibiting a unique graviton. Furthermore, each sector σ of these string systems shows the following properties: a) 26 effective degrees of freedom, b) a Lorentzian space-time with space-time dimension D(σ)≤ 26, c) an SO(D(σ)-1,1)-invariant ordinary string subsystem with quantized intercept less than or equal one, and d) an extra set of (26-D(σ)) twisted fields which are SO(D(σ)-1,1) scalars. Subexamples of non-tachyonic strings and four-dimensional strings are noted. Additionally, we discuss certain subsets of physical states of these theories, concluding that these investigations are so far consistent with the no-ghost conjecture for all the Lorentzian orbifold-string theories of permutation-type.