For nearly 25 years Calabi-Yau 3-folds have played a central role in string theory. Yet no explicit metric on these spaces was known. I will outline ideas pioneered by Donaldson and Yau that lead to such a metric on quintic Calabi-Yau 3-folds, at least numerically. If time allows, I will also extend this approach to solving the hermitian Yang-Mills equation. Knowledge of the metric is unavoidable if one is to extract physical predictions from string theory.

Continuation of Sept. 10 talk.

Off-shell representations of N-extended supersymmetry can be represented unambiguously in terms of certain graphs, called Adinkras. Their complete classification may be factored into specifying their topologies, and then the height-assignments for each topological type. The latter problem has been solved by a recursive mechanism that generates all height-assignments for a fixed topology. The former, coarser, classification is equivalent to classifying certain error-correcting codes and is being completed for N≤32.

I will review the latest development on the WARP direct search for WIMP dark matter at Gran Sasso. I will also review some recent results on the program for exploration of underground sources of argon depleted from 39Ar, and the prospects for use of this material in large WIMP detectors.

In this talk, after reviewing some basics of heterotic compactifications, I will describe a potential swampland issue in heterotic strings. Specifically, I will show how conventional heterotic string worldsheet constructions cannot describe arbitrary E8 gauge fields. I will then introduce new heterotic worldsheets, in particular "fibered WZW models" which can be used to describe more general E8 gauge fields.

I will discuss a method for computing correlators and chiral rings for (0,2) heterotic non-linear sigma models with toric targets, whose left-movers couple to a holomorphic deformation of the tangent bundle. The chiral ring for a family of deformations of the product of two rational curves' tangent bundle will be presented as a specific example. These computations provide a conceptually simple, though computationally complex, check of recent (0,2) mirror symmetry results.

The dense hadronic matter present in the interior of neutron stars and presumably in some stages of intermediate energy heavy-ion collisions is not cold. Indeed, the temperatures during the last stages of a supernova explosion can be of the order of 10-50 MeV and therefore thermal effects can be as important as those induced by the strong interaction between the constituents of the stars. We will discuss the properties of the hot and dense matter present in these scenarios and how some of its thermal properties can be inferred from experimental data. We will also try to outline how the thermal effects can be studied using different quantum many-body techniques. The implication of such effects in the neutrino emission/cooling of neutron stars will be discussed.

Einstein metrics, Yang-Mills gauge potentials and Lagrangian submanifolds on Kahler manifolds are important both in mathematics and physics. On the mathematical side there are several theorems that dictate when these non-linear PDEs' can be solved. In physics they are fundamental objects in N=1 of string compatifications. In this talk, we will discuss novel methods in Kahler quantization that allow us to approximate these objects to a high degree of accuracy.

I will discuss a source of strong-interaction phases in exclusive B meson decays. The current data of the B → K π direct CP asymmetry require a sizable strong phase in penguin amplitudes. Theoretically, its source has been a subject of controversy for several years; penguin annihilation amplitudes have a sizable imaginary part in the perturbative QCD approach, whereas they are almost real in the soft-collinear effective theory with the zero-bin subtraction. I will explain how to reconcile the opposite theoretical observations in two approaches.

I will describe a Lagrangian framework for coupling twisted Landau-Ginzburg theories to topological gravity on the string world-sheet. This is one of the simplest systems of matter coupled to quantum gravity, it provides a toy model of non-critical string theory, and it has a number of mathematical applications.

I propose manifestly U-duality invariant modular forms for the D4R4 and D6R4 interactions in type II string theory compactified on T2. These receive only a finite number of perturbative contributions, as well as non-perturbative contributions coming from D-instantons and (p,q) string instantons.

As noted long ago by Atiyah and Bott, the classical Yang-Mills action on a Riemann surface admits a beautiful symplectic interpretation as the norm-square of the moment map associated to the Hamiltonian action by gauge transformations on the affine space of connections. In this talk, I will explain how certain Wilson loop observables in Chern-Simons gauge theory on a Seifert three-manifold can be given an analogous symplectic description. Among other consequences, this fact implies that the stationary-phase approximation to the Wilson loop path integral is exact for torus knots, an observation made empirically by Lawrence and Rozansky prior to this work.

An explosive outburst from an evaporating primordal black hole can produce a coherent transient pulse detectable in the radio spectrum. Such a burst would occur in the presence of an extra dimension with a TeV compactification scale. I will discuss the production and detection of a transient pulse created by a primordial black hole in the presence of an extra dimension. I will also give an overview of the Eight-meter-wavelength Transient Array a Virginia Tech constructed instrument capable of detecting such a transient pulse.

I will describe a geometric point of view on the holomorphic anomaly equations of the topological string. This point of view leads to a simplification of the equations themselves and makes obvious the relation between the anomaly equations in the open and closed sectors. Physically it seems to be linked to dimensional reduction from d=4 to d=3.

I will present a new family of AdS₄ vacua in IIA string theory. The internal space is topologically the complex projective space CP³, but the metric relevant for us will be neither Einstein nor Kaehler. All known moduli will be stabilized by fluxes, without using quantum effects or sources.

Due to quantum fluctuations, spacetime is foamy on small scales. The degree of foaminess is found to be consistent with holography, a principle prefigured in the physics of black hole entropy. Applied to cosmology, the holographic model of spacetime foam requires the existence of dark energy which, we argue, is composed of an enormous number of inert "particles" of extremely long wavelength. We suggest that these "particles" obey infinite statistics in which all representations of the particle permutation group can occur. We also propose to detect spacetime foam by looking for halos in the images of distant quasars.

The MiniBooNE experiment at Fermilab, running since 2002, is designed to search for neutrino interactions as indicated by the LSND experiment. In addition to the neutrino oscillation search, MiniBooNE has measured neutrino interactions using very large data samples. The recently commissioned SciBooNE experiment, also at Fermilab on the same beamline, is also studying neutrino interactions with a high precision detector. The status and results from these experiments will be discussed along with new directions in neutrino detector technology.

We show that cosmological observables can constrain the topology of the compact additional dimensions predicted by string theory. This is done by relating cosmological observables to the microscopic parameters of the potentials and field-dependent kinetic terms of the multiple scalar fields that arise in the low-energy limit of string theory. We apply our formalism to the Large Volume Scenarios in Type IIB flux compactifications where analytical calculations are possible.

Particle physicists have become increasingly interested in precision cosmological tests over the last couple of decades. Supernovae, Galaxy Cluster, and the Cosmic Microwave Background surveys are all examples of observations that have proven useful for testing particle physics models. Galaxy cluster formation is particularly useful for studying the evolution of our universe since we can observe clusters forming over the last 10 billion years. I will first show how galaxy cluster formation models can be used in conjunction with observations to place constraints on cosmological parameters. Constraints on parameters will be shown using the recent ROSAT X-Ray Cluster survey. I will then discuss the sensitivity and insensitivity of cluster surveys for constraining physics beyond the standard model.

Recently the flavor composition of the neutrino mass states has been measured with increasing precision. However, the ν_e component of the third state, controlled by the mixing angle θ₁₃, together with the ordering of the neutrino masses remain unknown issues. Under the normal (inverted) hierarchy there is known resonant enhancement (suppression) of the ν_μ→ν_e three-flavor oscillation probability in matter for several GeV neutrinos with long baselines when θ₁₃ > 0. Conversely, anti-neutrinos experience suppression (enhancement). Expanding the standard oscillation analysis to incorporate all active neutrino flavors, Super-Kamiokande (SK) can exploit this asymmetry to address these open questions. The results of fits to the SK-I and SK-II atmospheric neutrino data under a three-flavor oscillation model for both hierarchies will be presented.

The Magellanic Clouds are the closest galaxies to our own. They differ from the Milky Way by having elemental abundances more similar to galaxies in the primordial Universe. The sensitivity of the Spitzer Space Telescope has enabled spectroscopic surveys of stars producing dust in the Magellanic Clouds, providing a glimpse of how evolved stars in these systems shed their mass, produce dust, and enrich the interstellar medium. Our spectra reveal that as the abundances become more primordial, the ejected mass and forming dust vary in several significant ways. The most important result is that the dust returned to the galaxy becomes more carbon-rich. These results demonstrate that the interstellar chemistry and radiative environments of high-redshift galaxies differ substantially from our own.

A dual to the Aharonov-Bohm effect exists, whereby an electric field generates a quantum phase along the path of a magnetic moment or spin. The dual quantum phase is referred to as the Aharonov-Casher phase. Through the Aharonov-Casher phase, spin-orbit interaction is predicted to produce a new collective state of matter which can be regarded as a spin dual to the fractional quantum Hall state. The fractional quantum Hall state is induced by an applied magnetic field under Coulombic electron-electron interactions in systems where kinetic energy is quenched. The new spin dual state in turn is predicted under applied electric fields when the ratio of effective spin-spin interactions to kinetic energy is high. We present experimental and materials conditions of spin-orbit interaction, spin-spin interactions and electric fields under which the new state may be observed.

During past few years we have depeloped techniques to construct exact analytic solutions in open string field theory (OSFT). We are now in a good position to explore things such as the dynamical aspects of tachyon condensation. We shall construct a light-cone time dependent solution of OSFT in an arbitrary linear dilaton background that has the amazing feature of asymptoting to the true tachyon vacuum in the far future.May

We present a novel solution to the low entropy and arrow of time puzzles of the initial state of the Universe. Our result derives from the physics of a diffeomorphism invariant extension of Matrix theory, formulated previously here at Tech, as the basis for a new quantum theory of gravity. The particular dynamical state space of this model, a nonlinear Grassmannian, has recently been studied by Michor and Mumford. They showed that the geodesic distance between any two points on this space vanishes. We translate this paradoxical mathematical result into a description of a hot, zero entropy state and an arrow of time after the Big Bang. The latter is seen as a far from equilibrium, large fluctuation driven, "freezing by heating" metastable ordered phase transition, a jamming transition of a non-linear dissipative dynamical system.