Fermionic states during closed-string tachyon condensation

Verify the conjecture that the non-perturbative fermionic excitations arising from ten-dimensional bosonic closed strings compactified on the \(SO(32)\) lattice become dynamically lighter during closed-string tachyon condensation.

Background

The paper proposes investigating whether the five tachyon-free closed superstring theories can emerge as perturbative expansions around tachyon-free stable coherent states of open bosonic string field theory. A central obstacle is that bosonic string theory conventionally contains only spacetime bosons, whereas superstring theories contain spacetime fermions.

The paper notes that bosonic closed strings compactified on the $SO(32)$ lattice possess non-perturbative fermionic excitations and explicitly formulates the unresolved conjecture that these states become lighter as the closed-string tachyon condenses. Confirming this behavior would be a step toward realizing closed superstring field theories as fluctuations around stable states of open bosonic string field theory.