High Energy Physics

Astrophysical observations spanning dwarf galaxies to galaxy clusters indicate that dark matter halos are less dense in their central regions compared to expectations from collisionless dark matter N-body simulations. Using detailed fits to dark matter halos of galaxies and clusters, we show that self-interacting dark matter may provide a consistent solution to the dark matter deficit problem across all scales, even though individual systems exhibit a wide diversity in halo properties. 

The mathematical notion of moonshine relates the theory of finite groups with that of modular objects. The first example, 'Monstrous Moonshine', was clarified in the context of two dimensional conformal field theory in the 90's. In 2010, interest in moonshine in the physics community was reinvigorated when Eguchi et. al. observed representations of the finite group M24 appearing in the elliptic genus of nonlinear sigma models on K3. In 2013, Cheng, Duncan, and Harvey provided a uniform construction of 23 new examples of moonshine, called 'umbral moonshine', of which M24 moonshine is a special case. 

In this talk, I will describe recent work studying the symmetries of certain Landau-Ginzburg orbifold theories that flow in the IR to c=6 N=(4, 4) superconformal field theories on the moduli space of K3 sigma models. We show that discrete symmetries of the UV theory implicate all 23 instances of umbral moonshine, not just M24 moonshine, in symmetries of K3 CFTs. I will then discuss a particular string theory compactification to three dimensions where we find a precise connection to all 23 umbral groups and type IIA string theory on K3.

Over the last few years it has become increasingly clear that there is a deep connection between quantum gravity and quantum information. The connection goes back to the discovery that black holes carry entropy with an amount given by the horizon area. I will present evidence that this is only the tip of the iceberg, and prove that a similar area law applies to more general Renyi entanglement entropies. To demonstrate the simplicity of this prescription, I will use it to calculate the mutual Renyi information between two disks of arbitrary dimension. Furthermore, I will provide quantum corrections to the area law and use it to solve the following important problem: what region of the dual spacetime is described by a subregion in a holographic theory? The answer to this question lies in a new perspective that I will advocate: holography is a quantum error correcting code.

The High-Energy community is only now in the process of fully appreciating the opportunities the LHC provides by producing electroweak-scale resonances beyond threshold. On the one hand this is reflected by changing from the so-called 'kappa framework’ to effective operators and on the other hand by studying Higgs and gauge boson production in processes with large momentum transfer. Accessing more exclusive phase space regions will allow to either discover New Physics or improve Higgs-boson couplings measurements. I will discuss implications of and tools necessary for these measurements, focusing on Higgs boson and Dark Matter phenomenology.

I will discuss a natural basis of CFT operators for probing dual gravitational physics in a diffeomorphism-invariant manner. On the CFT side, these operators are already well-known: they are 'OPE Blocks' that contribute to the Operator Product Expansion with fixed Casimir. On the gravity side, I will show that these OPE blocks are dual to diff-invariant geodesic or surface operators. Our new entry to the holographic dictionary can be understood as an operator generalization of the Ryu-Takayanagi proposal and I will show it gives a unified description for a host of important results in holography. 

I explain the hierarchy problem of the standard model of particle physics, and discuss some of the ideas which have been put forward to resolve it. I then show that a specific class of theories, built around a framework known as neutral naturalness, can help address this problem while remaining consistent with all current experimental tests. I explain that while certain theories in this class give rise to striking signals, others are extremely difficult to test, and require a detailed study of the properties of the Higgs boson. I consider the implications of these results for the Large Hadron Collider, and for future experimental programs.

Light sterile neutrinos are predicted in many theories beyond the Standard Model and may be hinted at in short-baseline data. However cosmological data seems to rule out these neutrinos. Intriguingly, this tension is ameliorated when these new neutrinos are self-interacting. I will explore the impact of this self-interaction on their evolution in the early universe and on the spectrum and flavor of IceCube's ultrahigh energy neutrinos.

The venerable proton continues to play a central role in fundamental particle physics.   Neutrinos scatter from protons in neutrino oscillation experiments, Weakly Interacting Massive Particles (WIMPs) are expected to scatter from protons in dark matter searches, and electrons or muons are bound by protons in precision atomic spectroscopy.   Our understanding of the proton is an obstacle to the success of next generation experiments hoping to discover CP violation in the lepton sector and determine the neutrino mass hierarchy, discover the particle nature of dark matter, or reveal new interactions such as those that violate lepton universality.  In this talk I present (i) an overview of the current state of knowledge in the neutrino sector, and theoretical advances that will determine a crucial missing ingredient in the predicted signal process of neutrino-nucleus scattering at long baseline neutrino oscillation experiments (ii) the first complete calculation of the scattering cross section of a proton on a static electroweak source, which determines WIMP-nucleus scattering rates at underground direct detection experiments and (iii) the status of the proton radius puzzle, whose most "mundane" resolution requires a 5 standard deviation shift in the value of the Rydberg constant.   I describe how each of these problems has spurred the development of powerful new methods in effective quantum field theory.

I will discuss the recent LHC excess in the di-photon distribution at an invariant mass of 750 GeV.  Various explanations in terms of weakly coupled and strongly coupled physics will be presented. Possible connection with Dark Matter will also be discussed.