Tachyon Condensation in Superstring Field Theory

TL;DR

This paper investigates tachyon condensation in superstring field theory, demonstrating that the computed potential approaches the expected vacuum energy and confirming the theory's consistency with D-brane tension predictions.

Contribution

It provides a detailed calculation of the tachyon potential to level three, showing significant progress towards the conjectured vacuum energy cancellation in superstring theories.

Findings

Achieved 85% of the expected vacuum energy at level three

The effective tachyon potential is bounded and has two degenerate minima

The kink solution's energy matches the lower-dimensional D-brane tension

Abstract

It has been conjectured that at the stationary point of the tachyon potential for the D-brane-anti-D-brane pair or for the non-BPS D-brane of superstring theories, the negative energy density cancels the brane tensions. We study this conjecture using a Wess-Zumino-Witten-like open superstring field theory free of contact term divergences and recently shown to give 60% of the vacuum energy by condensation of the tachyon field alone. While the action is non-polynomial, the multiscalar tachyon potential to any fixed level involves only a finite number of interactions. We compute this potential to level three, obtaining 85% of the expected vacuum energy, a result consistent with convergence that can also be viewed as a successful test of the string field theory. The resulting effective tachyon potential is bounded below and has two degenerate global minima. We calculate the energy density of the kink solution interpolating between these minima finding good agreement with the tension of the D-brane of one lower dimension.