A Cosmological Constant That is Too Small

TL;DR

This paper constructs a string theory vacuum with an extremely small negative cosmological constant, highlighting the challenge of achieving a positive vacuum energy in such models.

Contribution

It presents a novel string theory vacuum with an ultra-small negative cosmological constant and partial supersymmetry, advancing understanding of vacuum energy in string theory.

Findings

Vacuum energy magnitude < 10^{-123} in Planck units

Negative vacuum energy sign, some supersymmetry unbroken

Demonstrates difficulty in obtaining positive cosmological constant

Abstract

We construct a vacuum of string theory in which the magnitude of the vacuum energy is $< 10^{-123}$ in Planck units. Regrettably, the sign of the vacuum energy is negative, and some supersymmetry remains unbroken.