Search Talks

I discuss the latest developments on the Princeton Axion Search (PXS), a search for QCD axion dark matter in the 0.8-2.1 ueV mass range (200-500 MHz frequencies). PXS addresses the transitional range between cavity haloscopes and the DMRadio program, which operates below any cavity modes and utilizes lumped-element techniques. I describe development efforts on all aspects of the experimental apparatus, including the cryogenics, solenoidal magnet, near-quantum-limited readout amplifiers, and resonator. PXS leverages a partnership with the DOE Princeton Plasma Physics Laboratory to design and construct a large-bore, conduction-cooled solenoid. It also benefits from a partnership with Caltech/NASA JPL to implement parametric amplifiers in this frequency range. PXS is developing superconducting resonators and readouts beyond the Standard Quantum Limit of amplification in collaboration with the DMRadio program, which aims to probe the lower sub-ueV mass range. I discuss some of these collaborative efforts.

Ultralight scalar fields present a compelling dark matter candidate that can imprint potential signatures on observables spanning from the early Universe to today. In this talk, I will explore the implications of scalar dark matter that couples quadratically to the Standard Model. Such couplings induce temporal variations in the fundamental constants, leading to measurable effects on Big Bang Nucleosynthesis, the Cosmic Microwave Background, and equivalence principle tests. I will discuss how these changes influence the light element abundances and the CMB power spectrum, and how current cosmological data constrain this class of dark matter models. In addition, I will discuss the quadratically-coupled scalar dark matter manifests itself in equivalence principle tests.

Non-invertible symmetries have received a lot of attention in the last few years, with nontrivial applications in both high energy physics and condensed matter physics. I will discuss exact realizations of non-invertible symmetries on the lattice. Specifically, I will present a tensor network representation of non-invertible duality symmetries, such as the well known Kramers-Wannier duality in 1+1d and the Wegner duality in 3+1d, using a graphical tool from quantum information known as ZX-calculus. I will then discuss some low energy consequences of these symmetries in explicit lattice models. In particular, I will introduce a deformation of the 3+1d lattice Z2 gauge theory with exactly degenerate and (provably) gapped ground states, which include a product state and the toric code ground states. I’ll end with some generalisations and future directions.

The conformal bootstrap has been extremely successful for simple critical systems such as the 3D Ising model and vector models, where it has led to very precise determinations of critical exponents.

However, obtaining similarly reliable nonperturbative data for more complicated theories, especially conformal gauge theories, remains difficult. One practical obstruction is that the standard derivative basis converges slowly when the external operators have high conformal dimension. In this talk, I will describe an analytic functional approach to this problem. I will start from the one-dimensional story, where analytic functionals give bases dual to generalized free spectraand turn crossing into discrete sum rules. I will then explain how the construction can be lifted to higher dimensions using the factorization of two-dimensional global blocks together with dimensional reduction formulas for higher-dimensional conformal blocks. The result is a class of product analytic functionals acting directly on higher-dimensional crossing equations. I will discuss the convergence and positivity properties of these functionals and show that, unlike the standard derivative basis, they maintain fast convergence even when the external operators have high conformal dimension. I will then present numerical applications, including bounds and data extraction in the 3D Ising model, as well as extensions to bootstrap problems with global symmetry. I will end with possible applications to mixed-correlator bootstrap and strongly coupled conformal gauge theories.

In this talk, I will formulate a new class of primordial perturbations called kinetic isocurvature perturbations, where the mass density of dark matter is constant relative to the photon number density while the kinetic energy of dark matter fluctuates in space. Such perturbations naturally arise in scenarios where a nonrelativistic heavy field decays into relativistic dark matter particles with a spatially modulated rate. As dark matter cools and becomes nonrelativistic, these fluctuations in kinetic energy leave large-scale density perturbations essentially unaffected and therefore evade the Cosmic Microwave Background bounds on isocurvature perturbations, yet survive as spatial variations in the free-streaming scale, resulting in patch-by-patch variation of the matter power spectrum.

I will review an analogy between spectral theory of automorphic forms on hyperbolic d-manifolds and conformal field theory in d-1 dimensions. Building on this analogy, I will use the conformal bootstrap to prove a new bound on certain triple product L-functions. I will discuss in which sense the conformal/automorphic bootstrap provides a complete axiomatization of the underlying objects.