On the trivalent junction of three non-tachyonic heterotic string theories

A bstract Recently, Altavista, Anastasi, Angius and Uranga discussed a method to construct junctions and bouquets of different perturbative string theories. Following this analysis, we here argue that three non-tachyonic ten-dimensional heterotic string theories can be joined together at a nine-dimensional junction. This is done by creating a two-dimensional non-conformal 𝒩 = (0 , 1) supersymmetric quantum field theory with three asymptotic ends, each equipped with one of the worldsheet theories of the supersymmetric E 8 × E 8 theory, the supersymmetric SO(32) theory, and the non-supersymmetric SO(16) × SO(16) theory, respectively. It is actually a special case of a more general construction involving an arbitrary ℤ 2 -symmetric theory T , its ℤ 2 -orbifold T/ ℤ 2 , and the modified ℤ 2 -orbifold ( T × q ) / ℤ 2 , where q is a certain ℤ 2 -symmetric spin invertible theory.