Small Vacuum Energy and Tunneling in a Modified Bousso-Polchinski Model

TL;DR

This paper introduces a simplified string theory flux vacuum model that predicts small vacuum energies and analyzes tunneling transitions, applying it to a large Calabi-Yau database.

Contribution

It presents a new flux vacuum model with small energy spacing in thin wafers and applies it to the Sch"oller-Skarke database, revealing dominant giant flux leaps.

Findings

Most Calabi-Yau configurations have vacuum energy spacing ≤ 10^{-120} in Planck units.

Giant leaps dominate flux tunneling transitions in the model.

The universe's age constrains Calabi-Yau topologies, satisfied by the entire database.

Abstract

We propose a simplified model for the cosmological constant in string theory flux vacua motivated by type IIB and F-theory compactifications. Relative to the Bousso-Polchinski model, small vacuum energy spacing occurs in thin wafers rather than thin shells. The model is applied to the entire Sch\"oller-Skarke database of Calabi-Yau fourfolds, which exhibit $532,600,483$ distinct sets of Hodge numbers. The overwhelming majority of those ($99.95\%$ percent for some choices of parameters) exhibit a vacuum energy spacing of~$10^{-120}$ in Planck units or smaller. Brown-Teitelboim membrane nucleation transitions can populate this landscape of flux vacua. In the thin-wall approximation, and ignoring gravitational corrections, we find that the bubble transitions are always dominated by giant leaps in flux space. The age of the universe places a bound on Calabi-Yau topology that is satisfied for the entire Sch\"oller-Skarke database.