Narrow Results

Using software under development at Baylor University, we explicitly construct all layer 1 gauge, weakly coupled free fermionic heterotic string models up to order 22 in four large spacetime dimensions. The gauge models consist primarily of gauge content making a systematic construction process efficient. We present an overview of the model building procedure, redundancies in the process, methods used to reduce such redundancies and statistics regarding the occurrence of various combinations of gauge group factors and GUT groups. Statistics for both and models are presented.

Utilizing the gauge framework, software under development at Baylor University, we explicitly construct all layer 1 weakly coupled free fermionic heterotic string (WCFFHS) gauge models up to order 32 in four to ten large spacetime dimensions. These gauge models are well suited to large scale systematic surveys and, while they offer little phenomenologically, are useful for understanding the structure of the WCFFHS region of the string landscape. Herein, we present the gauge groups statistics for this swath of the landscape for both supersymmetric and non-supersymmetric models.

E₈ × E₈ heterotic string and M-theory, when appropriately compactified, can give rise to realistic, N = 1 supersymmetric particle physics. In particular, the exact matter spectrum of the MSSM, including three right-handed neutrino supermultiplets, one per family, and one pair of Higgs–Higgs conjugate superfields is obtained by compactifying on Calabi–Yau manifolds admitting specific SU(4) vector bundles. These "heterotic standard models" have the SU(3)_C × SU(2)_L × U(1)_Y gauge group of the standard model augmented by an additional gauged U(1)_{B – L}. Their minimal content requires that the B – L gauge symmetry be spontaneously broken by a vacuum expectation value of at least one right-handed sneutrino. In a previous paper, we presented the results of a renormalization group analysis showing that B – L gauge symmetry is indeed radiatively broken with a B – L/electroweak hierarchy of to . In this paper, we present the details of that analysis, extending the results to include higher order terms in tan β^-1 and the explicit spectrum of all squarks and sleptons.