High Energy Physics

I will discuss recent work studying universal properties of gravity in anti-de Sitter (AdS) spacetime from the perspective of conformal field theory (CFT). After reviewing relevant aspects of the AdS/CFT correspondence, I will demonstrate that all CFTs in three or more dimensions possess a spectrum of operators consistent with long-distance locality and Newtonian gravity in AdS. In generalizing these results to two-dimensional CFTs, I will then show that operators with large scaling dimension create classical backgrounds in the limit of large central charge. This result can be directly related to eigenstate thermalization in 2d CFTs and black hole geometries in 3d AdS. I will conclude by discussing methods for going beyond this large central charge limit in 2d and for studying black holes in higher dimensions.

The Most Wanted Particle

In what promises to be a smashing public lecture, Jon Butterworth will give a personal account of what it is like to work on the largest experiment ever built, the Large Hadron Collider at CERN. He will recount the excitement and tension surrounding the quest, under unprecedented media and public attention, to find the famous Higgs boson. Butterworth, a physics professor at University College London (UCL), will explain the motivation and importance of the Higgs search, discuss his specific research at CERN’s ATLAS detector, and speculate on the exciting breakthroughs that still await in the world of high-energy physics.

The discovery of the Higgs boson at the Large Hadron Collider marks the culmination of a decades-long hunt for the last ingredient of the Standard Model. At the same time, this discovery has started a new era in the search for more fundamental physics. In this talk, I will discuss what we have learned from the Higgs discovery about the mechanism of electroweak symmetry breaking and the implications for the existence of additional Higgs bosons. I will then highlight the future prospects of the Higgs boson in shedding light on New Physics and in particular on the nature of Dark Matter.

We will discuss techniques for computing 4-point functions of local operators in 2D conformal field theories, and their implications for semiclassical 3D quantum gravity. For generic 4-point functions, we present new closed-form expansions of the Virasoro conformal blocks. Specializing to correlators of holomorphic operators, these can be efficiently and exactly determined using an analytic implementation of the conformal bootstrap. Applying this method to the sewing construction of 2D CFT partition functions, we compute, via AdS/CFT, the semiclassical expansion of pure 3D quantum gravity around saddle point geometries of genus two; unlike at genus one, this expansion does not truncate at finite loop order.  

The presence of an instability in the Standard Model Higgs potential may have important implications for inflation and the viability of our Universe. In particular, if the Hubble scale during inflation is comparable to (or larger than) the instability scale of the potential, quantum fluctuations in the Higgs field will lead to the Higgs sampling the unstable part of the potential during inflation. However, to correctly study transitions to the unstable regime and determine the significance for the resulting universe requires addressing a number of subtleties. I will discuss these subtleties and a variety of possible approaches to studying Higgs evolution during inflation. By considering both (1) the evolution of Higgs fluctuations in the Gaussian approximation and (2) a perturbative calculation of the fluctuation two-point correlation function, I aim to elucidate how to address these issues in a consistent, physical way. The insight provided by these approaches will set the scene for studying Higgs fluctuations via the Fokker-Planck (FP) approach, which captures the non-Gaussian nature of the field. As such, it provides information about the rare—but, in terms of the fate of our Universe, potentially extremely important—patches that experience particularly large fluctuations.

In this talk I will propose a general correspondence which associates a non-perturbative quantum mechanical operator to a toric Calabi-Yau manifold, and I will propose a conjectural expression for its spectral determinant. As a consequence of these results, I will derive an exact quantization condition for the operator spectrum. I will give a concrete illustration of this conjecture by focusing on the example of local P2. This approach also provides a non-perturbative Fermi gas picture of topological strings on toric background and suggests the existence of an underlying theory of M2 branes behind this formulation.

With the increase of the center-of-mass energy from 8 TeV
to 13 TeV for LHC Run 2, the probability for boosted topologies will
become even higher than in Run 1. This also comes with a large
increase in pileup from the increased luminosity. This talk
investigates the state of the art of boosted algorithms and grooming
techniques, addresses shortcomings and possible improvements, and
discusses hot-topic items that will be interesting early on in Run 2.