Spinor-vector duality in image heterotic string vacua Original Research Article

Classification of the image space–time supersymmetric fermionic image heterotic-string vacua with symmetric internal shifts, revealed a novel spinor-vector duality symmetry over the entire space of vacua, where the image duality interchanges the spinor plus anti-spinor representations with vector representations. In this paper we demonstrate that the spinor-vector duality exists also in fermionic image heterotic string models, which preserve image space–time supersymmetry. In this case the interchange is between spinorial and vectorial representations of the unbroken image GUT symmetry. We provide a general algebraic proof for the existence of the image duality map. We present a novel basis to generate the free fermionic models in which the ten-dimensional gauge degrees of freedom are grouped into four groups of four, each generating an image modular block. In the new basis the GUT symmetries are produced by generators arising from the trivial and non-trivial sectors, and due to the triality property of the image representations. Thus, while in the new basis the appearance of GUT symmetries is more cumbersome, it may be more instrumental in revealing the duality symmetries that underly the string vacua.