Talks

It is a generic feature of strongly correlated electronic systems that several mechanisms (broadly represented by interactions) compete with each other. This competition often leads to the phenomenon of frustration. In strongly correlated systems such as doped Mott insulators kinetic energy and Coulomb repulsion frustrate the tendency of doped holes to phase separate. The result is the onset of a set of novel phases, which we dubbed Electronic Liquid Crystal (ELC) states, with varying degrees of complexity. Much like classical liquid crystals, electronic liquid crystal phases break translation and rotational invariance to varying degrees. In this talk I will focus on the experimental evidence and theory of two these phases, stripes and nematics, in several different systems including two-dimensional electron gases in large magnetic fields, ruthenate oxides, heavy fermions, and cuprate and pnictide superconductors.

Using the framework of deconstruction, we construct simple, weakly-coupled supersymmetric models that explain the Standard Model flavor hierarchy and produce a flavorful soft spectrum compatible with precision limits. Electroweak symmetry breaking is fully natural/ the mu-term is dynamically generated with no B mu-problem and the Higgs mass is easily raised above LEP limits without reliance on large radiative corrections. These models possess the distinctive spectrum of superpartners characteristic of 'effective supersymmetry': the third generation superpartners tend to be light, while the rest of the scalars are heavy.

I will describe the current state of our attempts to characterize the nature of the Dark Energy, the name given to the unknown phenomenology that is driving the observed accelerating cosmic expansion. There is a historical analogy between our current situation and the days of confusion before the advent of quantum mechanics. But while quantum physics emerged in a single academic generation, I fear that our attaining a deeper understanding of Dark Energy may not be as rapid. I will outline some steps we can take to try to avoid an extended period of sophisticated confusion and intellectual stagnation.

We use a field theoretic generalization of the Wigner-Weisskopf method to study the stability of the Bunch-Davies vacuum state for a massless, conformally coupled interacting test field in de Sitter space. A simple example of the impact of vacuum decay upon a non-gaussian correlation is discussed. Single particle excitations also decay into two particle states, leading to particle production that hastens the exiting of modes from the de Sitter horizon resulting in the production of \emph{entangled superhorizon pairs} with a population consistent with unitary evolution. We find a non-perturbative, self-consistent "screening" mechanism that shuts off vacuum decay asymptotically, leading to a stationary vacuum state in a manner not unlike the approach to a fixed point in the space of states.

After reviewing the basics of Coleman deLuccia tunneling, especially in the thin-wall limit, I discuss an (almost) exact tunneling solution in a piecewise linear and quadratic potential. A comparison with the exact solution for a piecewise linear potential demonstrates the dependence of the tunneling rate on the exact shape of the potential. Finally, I will mention applications when determining initial conditions for inflation in the landscape. Based on arXiv:1102.4742 [hep-th].

Neutrino oscillations has been observed and confirmed at two mass splittings (\Delta m^2), which is consistent with three generations of neutrinos and an unitary mixing matrix. Despite the rapid progress in understanding neutrino oscillations in the last decade, two large questions remain about neutrino oscillation parameters at \Delta m^2 ~ 0.001 eV^2. Is \theta_{23} exactly 45 degrees, indicating an additional symmetry in neutrino mixing? Is \theta_{13} non-zero, which would mean there could be CP violation in the neutrino sector. If \theta_{13} is large enough, then such CP violation could be studied with future high intensity experiments such as the proposed Long Baseline Neutrino experiment in the US (LBNE). The Tokai-To-Kamioka (T2K) long baseline neutrino experiment is designed to precisely measure \nu_{\mu} disappearance (\Delta m^2_{23}, \theta_{23}) and search for \nu_e appearance (\theta_{13}). A beam of muon neutrinos is generated at the J-PARC facility in Tokai-mura, Japan, and is sampled by two near detectors, ND280 and INGRID, before reaching the Super-Kamiokande detector, 295km away. In this talk, a first look at \nu_{\mu} disappearance and \nu_e appearance will be shown from T2K, from the inaugural 6 month run ending in June 2010 (3.23x10^19 protons on target, at 15.5 kW x 10^7s).