MIT Center for Theoretical Physics — a Leinweber Institute Publications

We develop a flow-based sampling algorithm for \(SU(N)\) lattice gauge theories that is gauge-invariant by construction. Our key contribution is constructing a class of flows on an \(SU(N)\) variable (or on a \(U(N)\) variable by a simple alternative) that respect matrix conjugation symmetry. We apply this technique to sample distributions of single \(SU(N)\) variables and to construct flow-based samplers for \(SU(2)\) and \(SU(3)\) lattice gauge theory in two dimensions.

Bounds on transport represent a way of understanding allowable regimes of quantum and classical dynamics. Numerous such bounds have been proposed, either for classes of theories, or, by using general arguments, universally for all theories. Few are exact and inviolable. I present a new set of methods for deriving exact, rigorous and sharp bounds on all coefficients of hydrodynamic dispersion relations, including diffusivity and the speed of sound. These general techniques combine analytic properties of hydrodynamics and the theory of univalent (complex holomorphic and injective) functions. Particular attention is devoted to bounds relating transport to quantum chaos, which can be established through pole-skipping in quantum field theories with classical holographic duals. Examples of such bounds are shown along with holographic theories that can demonstrate the validity of the necessary assumptions involved. I also discuss examples of bounds without relation to chaos.

TeV-scale particles that couple to the standard model through the weak force represent a compelling class of dark matter candidates. The search for such weakly interacting massive particles has already spanned multiple decades, and whilst it has yet to provide any definitive evidence for their existence, viable parameter space remains. In this paper, we show that the upcoming Cherenkov Telescope Array (CTA) has significant sensitivity to uncharted parameter space at the TeV mass scale. To do so, we focus on two prototypical dark matter candidates, the Wino and Higgsino. Sensitivity forecasts for both models are performed including the irreducible background from misidentified cosmic rays, as well as a range of estimates for the Galactic emissions at TeV energies. For each candidate, we find substantial expected improvements over existing bounds from current imaging atmospheric Cherenkov telescopes. In detail, for the Wino we find a sensitivity improvement of roughly an order of magnitude in ⟨σv⟩, whereas for the Higgsino we demonstrate that CTA has the potential to become the first experiment that has sensitivity to the thermal candidate. Taken together, these enhanced sensitivities demonstrate the discovery potential for dark matter at CTA in the 1–100 TeV mass range.