Fall 2014

Recently, Mintun, Polchinski, and Sun highlighted a subtlety in the effective description of a system of pair of D3-branes intersecting/overlapping in 1+1 dimension.  The issue they focused on was the existence/absence of solitons corresponding to D-string stretched between the D3-branes, which is expected to exist by S-duality (since the state corresponding to the F-string is included in the effective description.) We show that the subtleties identified by Mintun et.al. goes away if the angle between the D3-branes are scaled in a certain way as the alpha'->0 limit is taken.  In our scaling, the UV pathology encountered by Mintun et.al. is regulated by a tower of massive states whose spectrum and interaction is computable.

I will describe some aspects of holographic RG flows, including spontaneous symmetry breaking, the a-theorem and the holographic realization of the dilaton.

Abstract:  There has been a lot of recent progress in applying the conformal bootstrap technique to obtain non-perturbative information about various conformal field theories.   In this talk, I will focus on superconformal field theories with N=8 supersymmetry in three dimensions and show how to derive bounds on various operator dimensions and OPE coefficients in these theories.

In theories of semi-classical quantum gravity where the cosmological constant is considered a thermodynamic variable, the gravitational mass of a black hole has been shown to correspond to the enthalpy of the thermodynamic system, rather than the energy. The resulting extended thermodynamics now includes pressure and volume. This means that we can imagineer black hole heat engines that do useful mechanical work.  We present a study of some of these in anti-de Sitter (AdS) spacetime. We also propose that the extension should be used for all spacetime solutions, and consider the  case of Taub-NUT-AdS and Taub-Bolt-AdS geometries.

Recently, it has been proposed that in quantum gravity, the entanglement entropy of a general region should be finite and the leading contribution is given by the Bekenstein-Hawking area law. This spacetime entanglement conjecture motivates the study of 'hole-ography' in the AdS/CFT correspondence. The latter construction allows the Bekenstein-Hawking entropy of codimension-two surfaces in the bulk spacetime to be evaluated in terms of the entanglement entropies evaluated in the boundary theory.

The paradigm of a particle with constant eternal acceleration has long influenced thinking in a number of directions, from the question as to whether an accelerating particle radiates, to the quantum mystery of Unruh radiation,  to the question as to how EPR entanglement can be encoded in the classical geometry of the gravity dual of a quantum field theory.

This talk will revisit this paradigm in the context of N=4 Yang-Mills theory where the important question of quantum field theory interactions can be studied both in perturbation theory and at strong coupling using AdS/CFT, with some surprising conclusions.

I will discuss the discovery prospect of light dark matter with the  NOVA near detector at Fermilab. I will give first an overview on the current bounds on the quarks-light dark matter interaction and I will then explain why neutrino experiments can improve these bounds. Finally I  will focus on the NOVA experiment discussing  possible models and  parameter space  potentially constrained by this experiment.

Several methods exist for realising dark matter and gauge coupling unification in composite Higgs models.  I will give an overview of the most popular ideas, and show how they can be incorporated into complete, stand-alone models.  I will then discuss how renormalisable, UV completions of these models may be constructed, and what the top-down approach can tell us about low energy physics.

I will discuss two exciting prospects for future neutrino measurements.  New technological advancements make neutrino capture on tritium a promising path forward towards the detection of the CvB.  I will show that gravitational focusing by the Sun causes the expected neutrino capture rate to modulate annually. The amplitude and phase of the modulation depend on the phase-space distribution of the local neutrino background, which is perturbed by structure formation. Gravitational focusing is the only source of modulation for neutrino capture experiments, in contrast to dark-matter direct-detection searches where the Earth’s time-dependent velocity relative to the Sun also plays a role.  I will also show that CvB observatories may measure anisotropies in the cosmic neutrino velocity and spin distributions by polarizing the tritium targets.  

In the second part of my talk, I will propose the first truly directional antineutrino detector for antineutrinos above the hydrogen inverse beta decay threshold, with potential applications including monitoring for nuclear nonproliferation, spatially mapping geo-neutrinos, characterizing the diffuse supernova neutrino background, and searching for new physics in the neutrino sector. The design is a straightforward modification of existing antineutrino detectors; a prototype could be built with existing technology.

We discuss the origin of Holography in Higher Spin Gravity/O(N) Vector Model  Duality. Based on Bi-local fields of the CFT a bulk formulation of the theory is described first. It is then demonstrated that this representation corresponds to a "symmetric' gauge of Higher Spin Gravity

It is a familiar idea that the holographic duality between strongly coupled local quantum field theories and weakly coupled gravitational systems is inherently related to the renormalization group of the field theory. In this talk, I will describe a holographic interpretation of the exact renormalization group equations of theories near their free fixed points. This holographic description has an interpretation in terms of the unbroken phase of a higher spin gauge theory. A precise geometric interpretation of this theory can be described in terms of principal jet bundles.