A finite cutoff on the string worldsheet?

TL;DR

This paper proposes a modified prescription for D-brane backgrounds in string theory that ensures the Einstein equations align with worldsheet scale invariance, suggesting a finite worldsheet cutoff and connecting to recent theoretical developments.

Contribution

It introduces a new D-brane prescription that maintains known D-brane properties while achieving the Einstein-scale invariance equivalence, implying a finite worldsheet cutoff.

Findings

Modified D-brane prescription aligns Einstein equations with worldsheet scale invariance.

Suggests the worldsheet cutoff is finite, impacting string theory formulations.

Connects to recent work by Maldacena, Strominger, Gopakumar, and Vafa.

Abstract

D-brane backgrounds are specified in closed string theories by holes with appropriate mixed Dirichlet and Neumann boundary conditions on the string worldsheet. As presently stated, the prescription defining D-brane backgrounds is such that the Einstein equation is not equivalent to the condition for scale invariance on the string worldsheet. A modified D-brane prescription is found, that leads to the desired equivalence, while preserving all known D-brane lore. A possible interpretation is that the worldsheet cutoff is finite. Possible connections to recent work of Maldacena and Strominger, and Gopakumar and Vafa are suggested.