Supersymmetry Constraints and String Theory on K3

String theory, misaligned supersymmetry, and the supertrace constraints.

We demonstrate that string consistency in four spacetime dimensions leads to a spectrum of string states which satisfies the supertrace constraints Str1 = 0 and StrM2 ∝ Λ at tree level, where Λ is the one-loop string cosmological constant. This result holds for a large class of string theories, including critical heterotic strings. For strings lacking spacetime supersymmetry, these supertrace c...

M(atrix) String Theory on K3

We conjecture that M-theory compactiied on an ALE space (or K3) is described by 0-branes moving on the ALE space. We give evidence for this by showing that if we compactify another circle, we recover string theory on the ALE space. This guarantees that in the large N limit, the matrix model correctly describes the force law between gravitons moving in an ALE background. We also show the appeara...

1. Supersymmetry and String Theory

String Theory, Unification and Supersymmetry

One cannot yet point to any firm string prediction. While many approximate string ground states are known with interesting properties, we do not have any argument that one or another describes what we observe around us, and for reasons which appear fundamental we do not know how to systematically determine even any rough quantitative properties. I argue here that we should examine large classes...

Splitting Supersymmetry in String Theory

We point out that type I string theory in the presence of internal magnetic fields provides a concrete realization of split supersymmetry. To lowest order, gauginos are massless while squarks and sleptons are superheavy. We build such realistic U(3) × U(2) × U(1) models on stacks of magnetized D9-branes. Though not unified into a simple group, these theories preserve the successful supersymmetr...