Where is String Theory?

Understand

We use the S-matrix bootstrap to carve out the space of unitary, crossing symmetric and supersymmetric graviton scattering amplitudes in ten dimensions.

• We focus on the leading Wilson coefficient $\alpha$ controlling the leading correction to maximal supergravity.
• The negative region $\alpha<0$ is excluded by a simple dual argument based on linearized unitarity (the desert).
• A whole semi-infinite region $\alpha \gtrsim 0.14$ is allowed by the primal bootstrap (the garden).