Factorization of Chiral String Amplitudes

Understand

We re-examine a closed-string model defined by altering the boundary conditions for one handedness of two-dimensional propagators in otherwise-standard string theory.

• We evaluate the amplitudes using Kawai-Lewellen-Tye factorization into open-string amplitudes.
• The only modification to standard string theory is effectively that the spacetime Minkowski metric changes overall sign in one open-string factor.
• This cancels all but a finite number of states: As found in earlier approaches, with enough supersymmetry (e.g., type II) the tree amplitudes reproduce those of the massless truncation of ordinary string theory.