Toward the classification of the realistic free fermionic models

TL;DR

This paper explores the structure and classification of realistic free fermionic models in string theory, highlighting how free phases influence phenomenology and connecting model symmetries to physical properties.

Contribution

It provides a detailed analysis of the construction, classification, and role of free phases in free fermionic models, offering insights into their phenomenological implications.

Findings

Identification of key building blocks in model construction

Connection between free phases and mirror symmetry

Impact of free phases on low-energy phenomenology

Abstract

The realistic free fermionic models have had remarkable success in providing plausible explanations for various properties of the Standard Model which include the natural appearance of three generations, the explanation of the heavy top quark mass and the qualitative structure of the fermion mass spectrum in general, the stability of the proton and more. These intriguing achievements makes evident the need to understand the general space of these models. While the number of possibilities is large, general patterns can be extracted. In this paper I present a detailed discussion on the construction of the realistic free fermionic models with the aim of providing some insight into the basic structures and building blocks that enter the construction. The role of free phases in the determination of the phenomenology of the models is discussed in detail. I discuss the connection between the free phases and mirror symmetry in (2,2) models and the corresponding symmetries in the case of the (2,0) models. The importance of the free phases in determining the effective low energy phenomenology is illustrated in several examples. The classification of the models in terms of boundary condition selection rules, real world-sheet fermion pairings, exotic matter states and the hidden sector is discussed.