A different kind of four dimensional brane for string theory

TL;DR

This paper introduces a novel four-dimensional brane model extending the Polyakov action, which differs from traditional D-branes but shares some structural features, and explores its quantization and low-energy implications.

Contribution

It proposes a new conformally invariant four-dimensional brane model and analyzes its quantization, critical dimension, and low-energy effective equations.

Findings

Identifies a critical spacetime dimension for the new brane.

Derives Einstein's equations coupled to a scalar dilaton in the low-energy limit.

Introduces a tensor structure relevant at low energies.

Abstract

We present a generalization of the string's Polyakov action that describes a conformally invariant four dimensional brane. The new extended object is very different from the traditional D-branes of string theory, but, nevertheless, shares some structural similarities with the string, especially when it comes to the low-energy limit of small tension. We introduce a rather rich structure of tensors that can play a role at low energies. In analogy with the bosonic string, we initiate the quantization of the new brane discussing the extent in which it produces a critical dimension of spacetime and Einstein's equations coupled to a scalar dilaton under some approximations.