Boundary Modes in String Field Theory

Fuente: arXiv
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Main Authors: Maccaferri, Carlo, Poletti, Riccardo, Ruffino, Alberto, Vošmera, Jakub
Format: Preprint
Published: 2025
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_version_ 1866916632088018944
author Maccaferri, Carlo
Poletti, Riccardo
Ruffino, Alberto
Vošmera, Jakub
author_facet Maccaferri, Carlo
Poletti, Riccardo
Ruffino, Alberto
Vošmera, Jakub
contents We discuss the construction of boundary contributions to free string field theory actions in the context of the bosonic string. We show that it is generally possible to obtain a well-defined variational principle by adding a simple boundary term (which only depends on the value of the bulk fields at the boundary) to the original bulk action. However, it is in general not possible to do this in a gauge-invariant way unless suitable boundary degrees of freedom are added. We explicitly construct such boundary contributions for the massless level of both the open and the closed SFT, as well as for the tensionless limit of the full string field theory. Our results reproduce linearized general relativity with the Gibbons-Hawking-York term and provide similar gauge-invariant actions for the infinite tower of massless higher-spin gauge theories for all Regge trajectories. By writing down a gauge-invariant action for the first massive level of the open string, we provide evidence that an analogous construction should be possible for the full tensile string field theory.
format Preprint
id arxiv_https___arxiv_org_abs_2502_19373
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Boundary Modes in String Field Theory
Maccaferri, Carlo
Poletti, Riccardo
Ruffino, Alberto
Vošmera, Jakub
High Energy Physics - Theory
We discuss the construction of boundary contributions to free string field theory actions in the context of the bosonic string. We show that it is generally possible to obtain a well-defined variational principle by adding a simple boundary term (which only depends on the value of the bulk fields at the boundary) to the original bulk action. However, it is in general not possible to do this in a gauge-invariant way unless suitable boundary degrees of freedom are added. We explicitly construct such boundary contributions for the massless level of both the open and the closed SFT, as well as for the tensionless limit of the full string field theory. Our results reproduce linearized general relativity with the Gibbons-Hawking-York term and provide similar gauge-invariant actions for the infinite tower of massless higher-spin gauge theories for all Regge trajectories. By writing down a gauge-invariant action for the first massive level of the open string, we provide evidence that an analogous construction should be possible for the full tensile string field theory.
title Boundary Modes in String Field Theory
topic High Energy Physics - Theory
url https://arxiv.org/abs/2502.19373