A Landscape in Boundary String Field Theory: New Class of Solutions with Massive State Condensation

TL;DR

This paper explores non-perturbative vacua in boundary string field theory by numerically finding a vast landscape of solutions with varying energies, including states with small vacuum energy, interpreted as perturbative closed string states.

Contribution

It introduces a new class of solutions with massive state condensation in boundary string field theory and analyzes their energy distribution through numerical methods.

Findings

Numerous solutions with energies between D-brane tension and tachyon vacuum energy.

Distribution of solutions forms a dense landscape including states with small vacuum energy.

Solutions are interpreted as perturbative closed string states.

Abstract

We solve the equation of motion of boundary string field theory allowing generic boundary operators quadratic in $X$, and explore string theory non-perturbative vacua with massive state condensation. Using numerical analysis, a large number of new solutions are found. Their energies turn out to distribute densely in the range between the D-brane tension and the energy of the tachyon vacuum. We discuss an interpretation of these solutions as perturbative closed string states. From the cosmological point of view, the distribution of the energies can be regarded as the so-called landscape of string theory, as we have a vast number of non-perturbative string theory solutions including one with small vacuum energy.