Quark Lepton Symmetry Across Scales with Sumit Biswas

The Pati–Salam symmetry provides a simple way of unifying quarks and leptons by treating lepton number as the fourth color. In this talk, I will discuss two different realizations of this symmetry. I will first show how Pati–Salam symmetry can survive down to the TeV scale, despite the usually very strong flavor constraints, and discuss some of its signatures in lepton flavor violation and at colliders. I will then move to a universal-seesaw realization, where the observed fermion masses arise through mixing with vector-like fermions. An interesting feature of this setup is that neutrinos remain massless at tree level and acquire their masses radiatively. I will focus mainly on what these two examples teach us about fermion masses, neutrino masses, and flavor in theories with quark–lepton symmetry.

This lecture was made possible by the William C. Ferguson Fund.