Zenith Grant Awardee

Dr. A. Garrett Lisi

Theiss Research

Project Title

E8 Theory

Project Summary

The Standard Model of particle physics provides an accurate but disjointed description of nature. Each different force–electromagnetic, weak, and strong–is described by a different, smooth geometric shape, called a Lie group, moving over our four dimensions of space-time. Each force particle–photon, weak boson, and gluon–is identified with a symmetry of the corresponding shape. The matter particles–electrons, neutrinos, and quarks–interact with the different forces according to their separate electric, weak, and strong charges. Gravity may also be described as a curved shape moving over our space-time, interacting with matter according to its mass and spin. The particle masses arise from interaction with the Higgs field, which also interacts with gravity and the other forces. It is the goal of E8 Theory to develop a unified description of all fundamental particle fields as the symmetries of a single shape. All known fields–the four forces, Higgs, and matter–would be various parts of single, quantized geometric field describing a beautiful shape moving and twisting over our four dimensions of space-time. The most promising candidate for this shape is the largest simple exceptional Lie group, E8, which matches the fields of the Standard Model and gravity remarkably well–but all geometries will be considered in this exciting search.

Technical Abstract

There are several clues that the fields of the Standard Model and gravity may be unified within a larger Lie group. The renormalization flows of the U(1), SU(2), and SU(3) coupling constants roughly converge at high energies, consistent with a description of the known gauge fields as parts of the principal bundle connection of a Grand Unified Theory. The fact that the weak bosons couple only to the left chiral parts of fermions indicates a nontrivial relationship between gauge and internal gravitational symmetries. Also, the Dirac masses of the fermions, involving interactions between their left and right chiral parts and the Higgs field, require the combined use of the gravitational frame and Higgs fields in curved spacetime. And, remarkably, the algebraic structure of the fermions matches the peculiar structure of the exceptional Lie groups, allowing all fields and their interactions to be described by a single superconnection and its curvature.

The E8 Theory project seeks to extend the successful GUT program and achieve the geometric unification of gauge, Higgs, and gravitational fields as parts of the quantized connection of a single Lie group or supergroup. One promising description employing the E8 Lie group will be developed further, and others considered.