2025/08/02 by Sebastián Bahamondes, Bahamondes, Sebastián
Physics and Astronomy · #Black Holes and Theoretical Physics #FOS: Physical sciences #High Energy Physics - Theory (hep-th) #Noncommutative and Quantum Gravity Theories #Other Condensed Matter (cond-mat.other) #Topological Materials and Phenomena
paper · pdf · doi:10.48550/arxiv.2508.01497
openalex publication_date 2025/08/02 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
In this thesis we build a phenomenological, strongly coupled quantum field theory in 2+1-dimensions through AdS/CFT holography, by building a 3+1-dimensional, negatively curved gravity theory with a SU(2) gauge field, and a scalar field in the adjoint of SU(2). We locate a phase transition between two distinct phases at zero and finite temperature, which are characterized through the dispersion relation of quasi-normal modes of probe fermions in the bulk, and correspond either to a Dirac semimetal or a band insulator. These phases are separated by a critical phase/critical point (depending if T>0 or T=0, respectively) where the band structure of boundary fermions exhibits semi-Dirac anisotropy. We characterize each phase at T=0 by explicit solutions to the bulk equations of motion in the infra-red, and determine that the critical point's spacetime is a Lifshitz geometry, whose dynamical critical exponent is approximately equal to 2. We also find that this anisotropy induces a non-trivial scaling of the shear viscosity-entropy density ratio with respect to temperature in the T→ 0 limit, and find evidence that the anisotropic phase of the system corresponds to a finite-temperature quantum critical phase.