Tracing New Physics: From Symmetry to Observation

Author: Patrone, Samuel

Year: 2026

Degree: Dissertation (Ph.D.)

Advisor: Wise, Mark B.

Committee Members: Weinstein, Alan Jay; Papucci, Michele; Murgui Galvez, Clara; Wise, Mark B.

Option: Physics

Abstract

Despite the success of the Standard Model of particle physics and the λCDM model of cosmology in describing many aspects of nature, several fundamental questions still demand extensions of our current understanding. This thesis studies how effective descriptions and symmetry principles can be used to trace possible new physics and understand their effect on low-energy observables.

The first part focuses on large-scale structure as a probe of primordial physics. Since galaxies are biased tracers of the underlying matter density field, extracting primordial information from galaxy surveys requires a controlled treatment of nonlinear gravitational evolution, galaxy bias, and short-distance sensitivity. We study the renormalization of composite operators in the galaxy bias expansion in the presence of local primordial non-Gaussianity, showing how different ultraviolet regulators affect counterterm coefficients while preserving the structures fixed by symmetry.

The second part turns to physics beyond the Standard Model. We study finite naturalness in Pati-Salam theories of quark-lepton unification, deriving constraints from finite threshold corrections to the Higgs mass. We then investigate long-lived axion-like particles in beam-dump experiments, showing that electromagnetic cascades can substantially enhance the sensitivity of such searches. Finally, we study leptogenesis in automatic Nelson-Barr models, identifying viable regions where spontaneous CP violation can both protect the quality of the strong CP solution and generate the observed baryon asymmetry.

Together, these results trace new physics from symmetry to observation, showing how effective descriptions turn microscopic principles into cosmological and experimental targets.