I will discuss new, general, and simple positivity bounds at finite momentum transfer. Massive gravity violates these bounds unless its cutoff (the mass gap M to new states) is within one order of magnitude of the graviton mass M≲ O(10)m. Non-gravitational effective theories of massive spin-2 or higher spin are similarly bounded.

 

The holographic principle posits a radical way to quantify gravitational physics. It claims that all information of a gravitational theory in a region of space can be encoded by a quantum theory at the boundary of this region. During this colloquium, I will define gravity from a boundary perspective. We will see how one can construct gravity through this relationship, using possible quantum theories on the boundary as materials for the undertaking. The presentation will focus on the large-N limit of two-dimensional symmetric product orbifolds: this will be the material.  I will show how one can single out which symmetric product orbifold theory could lead to a strongly coupled point in their moduli space, whose dual could be a semi-classical theory of AdS_3 gravity. In this process, strange, counter-intuitive and also novel effects will occur which will be discussed.

I will review how SGWBs are sourced and how the GW sky will appear at different frequencies. I will discuss how information in the SGWBs can be mined and review the present and future observational landscape.

"Analogue" Hamiltonian simulation involves engineering a Hamiltonian of interest in the laboratory and studying its properties experimentally. Large-scale Hamiltonian simulation experiments have been carried out in optical lattices, ion traps and other systems for two decades. Despite this, the theoretical basis for Hamiltonian simulation is surprisingly sparse. Even a precise definition of what it means to simulate a Hamiltonian was lacking.

 

AdS/CFT duality postulates that quantum gravity in a d-dimensional anti-de-Sitter bulk space is equivalent to a strongly interacting field theory on its d-1 dimensional boundary. Recently, connections between AdS/CFT duality and quantum error-correcting codes have led (amongst other things) to tensor network toy models that capture important aspects of this holographic duality. However, these toy models struggle to encompass dualities between bulk and boundary energy scales and dynamics.

 

On the face of it, these two topics seem to have nothing whatsoever to do with one another.

 

In this talk, I will explain how we put analogue Hamiltonian simulation on a rigorous theoretical footing, by drawing on techniques from Hamiltonian complexity theory and Jordan algebras. I will show how this proved far more fruitful than a mere mathematical tidying-up exercise, leading to the discovery of universal quantum Hamiltonians [Science, 351:6 278, p.1180, 2016], [Proc. Natl. Acad. Sci. 115:38 p.9497, 2018]. And I will explain how this new Hamiltonian simulation formalism allowed us to extend the toy models of AdS/CFT to encompass energy scales, dynamics, and even (toy models of) black hole formation [J. High Energy Phys 2019:17; J. High Energy Phys 2022:52]. Finally, I will also discuss the significant limitations of tensor networks as toy models of AdS/CFT duality, and what these results suggest about possible ways forward.

 

With the absence of the discovery of new heavy particles at the LHC, the search for new physics has turned to using precision measurements to uncover the footprints of BSM physics.  The Standard Model Effective Field Theory is a useful tool for these searches and I will discuss developments in the SMEFT and in the interpretation of SMEFT measurements at the LHC.

 

 

I will do a colloquium-style survey of some developments in black hole physics that have occurred in recent years. This selection will choose developments that have the potential to be useful for present or future projects of researchers in the audience, focusing on an interplay between theory, phenomenology and high-energy physics.

Scattering amplitudes are an important observable in quantum field theory. However, in certain quantum field theories (such as quantum chromodynamics or QCD) it can be very challenging to reliably predict the amplitudes of low-energy bound states called hadrons. In this talk, I will explain how progress has been made by deriving mathematical relations between amplitudes and the discrete energies of the system confined to a finite, periodic volume. This is useful, in part because methods exist to calculate those energies numerically, but I will also argue that such relations have taught important general lessons about low-energy scattering.

Ground-based microwave background maps have now surpassed Planck in sensitivity, at higher spatial
resolution. I will review some of the main science results from the Atacama Cosmology Telescope DR6 data set, with a particular focus
on cosmological model constraints, gravitational lensing, and the thermal and kinematic Sunyaev-Zeldovich
effect. This sets the stage for Simons Obsevatory, the next-generation microwave experiment currently under
construction in Chile. SO will build on the successes of ACT, Simons Array, and BICEP, and aims to map
the sky in many frequency bands at angular scales ranging from an arcminute up to a few degrees. Science
goals of SO include growth of structure and gravitation; primordial tensor perturbations from inflation; number of
relativistic particle species and total neutrino mass; primordial magnetic fields and cosmic birefringence; and
cosmological model constraints.

In this talk, I will highlight the need to consider dark matter candidates and signatures in a holistic and self-consistent manner. I will use pseudo-Dirac dark matter, a longtime favourite for model-builders and a prolific “anomaly fixer,” as a case study. Surprisingly, the parameter space for this candidate still has yet to be fully explored, and I will show two regions of the parameter space where qualitatively new production mechanisms arise. I will then show the various ways these production mechanisms will be manifest in the subsequent cosmology, astrophysical systems, and terrestrial experiments. The complementarity of these systems, which can constrain different parts of the parameter space, can be used in tandem for the eventual detection or exclusion of this dark matter model.

Neutrinos are fascinating elementary particles heralding the dawn of the multi-messenger astronomy era. Neutrinos affect the stellar dynamics, drive the formation of new elements, and carry signatures of the yet mysterious physics ruling the most powerful cosmic fireworks. Recent developments on the role of neutrinos in compact astrophysical sources will be reviewed together with the most exciting detection prospects.