Bose-Fermi Degeneracy and Duality in Non-Supersymmetric Strings

TL;DR

This paper constructs non-supersymmetric string models with equal bosons and fermions at all mass levels, leading to vanishing cosmological constant contributions at multiple loops and suggesting a possible all-loop cancellation.

Contribution

It introduces asymmetric orbifold models exhibiting bose-fermi degeneracy and explores their duality, indicating potential non-perturbative stability of the cosmological constant.

Findings

One-loop and two-loop cosmological constant contributions vanish.

Models exhibit bose-fermi degeneracy at all mass levels.

Dual models suggest absence of certain non-perturbative corrections.

Abstract

Following Kachru, Kumar and Silverstein, we construct a set of non-supersymmetric Type II string models which have equal numbers of bosons and fermions at each mass level. The models are asymmetric {\bf Z}_2 \otimes {\bf Z}_2^{\prime} orbifolds. We demonstrate that this bose-fermi degeneracy feature implies that both the one-loop and the two-loop contributions to the cosmological constant vanish. We conjecture that the cosmological constant actually vanishes to all loops. We construct a strong-weak dual pair of models, both of which have bose-fermi degeneracy. This implies that at least some of the non-perturbative corrections to the cosmological constant are absent.