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High Energy Physics - Theory, hep-th
Abstract:
We continue our investigation of Z-theory, the second double-copy component
of open-string tree-level interactions besides super-Yang-Mills (sYM). We show
that the amplitudes of the extended non-linear sigma model (NLSM) recently
considered by Cachazo, Cha, and Mizera are reproduced by the leading
alpha'-order of Z-theory amplitudes in the semi-abelian limit. The extension
refers to a coupling of NLSM pions to bi-adjoint scalars, and the semi-abelian
limit refers to a partial symmetrization over one of the color orderings that
characterize the Z-theory amplitudes. Alternatively, the partial symmetrization
corresponds to a mixed interaction among abelian and non-abelian states in the
underlying open-superstring amplitude. We simplify these permutation sums via
monodromy relations which greatly increase the efficiency in extracting the
alpha'-expansion of these amplitudes. Their alpha'-corrections encode
higher-derivative interactions between NLSM pions and bi-colored scalars all of
which obey the duality between color and kinematics. Through double copy, these
results can be used to generate the predictions of supersymmetric
Dirac-Born-Infeld-Volkov-Akulov theory coupled with sYM as well as a complete
tower of higher-order alpha'-corrections.
