Superconformal anomaly free models in D=4

TL;DR

This paper constructs modified four-dimensional heterotic string models with superconformal symmetry and anomaly freedom, potentially explaining a vanishing cosmological constant and fermion generation structure.

Contribution

It introduces a new class of heterotic string models incorporating R flux tubes with superconformal symmetry and anomaly cancellation, advancing string model building.

Findings

Models support local superconformal symmetry consistent with quantum mechanics.

Anomaly freedom may relate to a naturally vanishing cosmological constant.

R charge may influence fermion generation ordering.

Abstract

A family of modified $(0,1)$ heterotic string models in D=4 is constructed in which the strings incorporate $R$ flux tubes which may in special cases support a local spacetime superconformal symmetry consistent with quantum mechanics. There is an intrinsic Goldstino multiplet, so that supersymmetry breaking can be driven by any process that generates a non-zero value for the superpotential. The superconformal anomaly freedom of these models may be related to a naturally vanishing $\Lambda$. The $R$ charge of such models may also play a role in producing a generation-ordered fermion spectrum. \