We describe a method to extract an effective Lagrangian description for open bosonic strings, at zero transcendentality. The method relies on a particular formulation of its scattering amplitudes derived from color-kinematics duality. More precisely, starting from a $(DF)^2 + \text{ YM}$ quantum field theory, we integrate out all the massive degrees of freedom to generate an expansion in the inverse string tension $\alpha^\prime$. We explicitly compute the Lagrangian terms through $\mathcal{ O}(\alpha^{ \prime 4})$, and target the sector of operators proportional to $F^4$ to all orders in $\alpha^\prime$.
Categories: hep-th