All-Order Quartic Couplings in Highly Symmetric D-brane-Anti-D-brane Systems

We compute six-point string amplitudes for the scattering of one closed string Ramond-Ramond state, two tachyons, and two gauge fields in the worldvolume of D-brane-anti-D-brane systems in the Type II superstring theories. From the resulting S-matrix elements, we read off the precise form of the couplings, including their exact numerical coefficients, of two tachyons and two gauge fields in the corresponding highly symmetric effective field theory (EFT) Lagrangian in the worldvolume of D-brane-Anti-D-brane to all orders in $\alpha'$, which modify and complete previous proposals. We verify that the EFT reproduces the infinite collection of stringy gauge field singularities in dual channels. Inspired by interesting similarities between the all-order highly symmetric EFTs and holographic duals of Vasiliev's higher spin gravities \`a l\`a Nilsson and Vasiliev, we make a proposal for tensionless limits of D-brane-anti-D-brane systems.