# String Phenomenology From a Worldsheet Perspective

## TL;DR

This paper explores non-supersymmetric tachyonic superstrings as potential foundations for realistic string models, presenting a tachyon-free Standard-like Model and proposing a connection between different heterotic-string theories to better understand the string landscape.

## Contribution

It introduces a tachyon-free Standard-like Model from orbifolding heterotic strings and suggests a conjecture linking (2,0) and (2,2) heterotic theories, aiding in classifying viable string vacua.

## Key findings

- A tachyon-free six-generation Standard-like Model is constructed.
- Evidence is provided that (2,0) heterotic strings can connect to (2,2) models.
- Implications for identifying swampland theories and understanding moduli spaces.

## Abstract

I argue that the ten dimensional non--supersymmetric tachyonic superstrings may serve as good starting points for the construction of viable phenomenological vacua. Thus, enlarging the space of possible solutions that may address some of the outstanding problems in string phenomenology. A tachyon free six generation Standard--like Model is presented, which can be regarded as an orbifold of the $SO(16)\times E_8$ heterotic--string in ten dimensions. I propose that any $(2,0)$ heterotic--string in four dimensions can be connected to a $(2,2)$ one via an orbifold or by interpolations and provide some evidence for this conjecture. It suggests that any Effective Field Theory (EFT) model that cannot be connected to a $(2,2)$ theory is necessarily in the swampland, and will simplify the analysis of the moduli spaces of $(2,0)$ string compactifications.