Two Higgs Pair Heterotic Vacua and Flavor-Changing Neutral Currents

TL;DR

This paper constructs a heterotic M-theory vacuum with a realistic MSSM spectrum, featuring an extra Higgs pair and suppressed flavor-changing neutral currents due to stringy selection rules, aligning with experimental bounds.

Contribution

It introduces a heterotic M-theory vacuum with a specific Calabi-Yau structure that naturally suppresses flavor-changing neutral currents through stringy selection rules.

Findings

Realistic quark/lepton mass hierarchy achieved.

Suppression of Higgs-mediated flavor-changing neutral currents.

Model consistent with experimental bounds on flavor processes.

Abstract

We present a vacuum of heterotic M-theory whose observable sector has the MSSM spectrum with the addition of one extra pair of Higgs-Higgs conjugate superfields. The quarks/leptons have a realistic mass hierarchy with a naturally light first family. The double elliptic structure of the Calabi-Yau compactification threefold leads to two ``stringy'' selection rules. These classically disallow Yukawa couplings to the second Higgs pair and, hence, Higgs mediated flavor-changing neutral currents. Such currents are induced in higher-dimensional interactions, but are naturally suppressed. We show that our results fit comfortably below the observed upper bounds on neutral flavor-changing processes.