TASI Lectures: Particle Physics from Perturbative and Non-perturbative Effects in D-braneworlds

In these notes we review aspects of semi-realistic particle physics from the point of view of type II orientifold compactifications. We discuss the appearance of gauge theories on spacetime filling D-branes which wrap non-trivial cycles in the Calabi-Yau. Chiral matter can appear at their intersections, with a natural interpretation of family replication given by the topological intersection number. We discuss global consistency, including tadpole cancellation and the generalized Green-Schwarz mechanism, and also the importance of related global $U(1)$ symmetries for superpotential couplings. We review the basics of D-instantons, which can generate superpotential corrections to charged matter couplings forbidden by the global $U(1)$ symmetries and may play an important role in moduli stabilization. Finally, for the purpose of studying the landscape, we discuss certain advantages of studying quiver gauge theories which arise from type II orientifold compactifications rather than globally defined models. We utilize the type IIa geometric picture and CFT techniques to illustrate the main physical points, though sometimes we supplement the discussion from the type IIb perspective using complex algebraic geometry.Comment: 35 pages. Based on lectures given by M.C. at TASI 2010. v2: added references, fixed typo

USING NATURE AS BOTH MENTOR AND MODEL: ANIMAL WELFARE RESEARCH AND DEVELOPMENT IN SUSTAINABLE SWINE PRODUCTION

Livestock Production/Industries,

Air fluorescence detection of large air showers below the horizon

In the interest of exploring the cosmic ray spectrum at energies greater than 10 to the 18th power eV, where flux rates at the Earth's surface drop below 100 yr(-1) km(-2) sr(-1), cosmic ray physicists have been forced to construct ever larger detectors in order to collect useful amounts of data in reasonable lengths of time. At present, the ultimate example of this trend is the Fly's Eye system in Utah, which uses the atmosphere around an array of skyward-looking photomultiplier tubes. The air acts as a scintillator to give detecting areas as large as 5000 square kilometers sr (for highest energy events). This experiment has revealed structure (and a possible cutoff) in the ultra-high energy region above 10 o the 19th power eV. The success of the Fly's Eye experiment provides impetus for continuing the development of larger detectors to make accessible even higher energies. However, due to the rapidly falling flux, a tenfold increase in observable energy would call for a hundredfold increase in the detecting area. But, the cost of expanding the Fly's Eye detecting area will approximately scale linearly with area. It is for these reasons that the authors have proposed a new approach to using the atmosphere as a scintillator; one which will require fewer photomultipliers, less hardware (thus being less extensive), yet will provide position and shower size information

The Bing-Borsuk and the Busemann Conjectures

We present two classical conjectures concerning the characterization of manifolds: the Bing Borsuk Conjecture asserts that every $n$-dimensional homogeneous ANR is a topological $n$-manifold, whereas the Busemann Conjecture asserts that every $n$-dimensional $G$-space is a topological $n$-manifold. The key object in both cases are so-called {\it generalized manifolds}, i.e. ENR homology manifolds. We look at the history, from the early beginnings to the present day. We also list several open problems and related conjectures.Comment: We have corrected three small typos on pages 8 and

Set-partition tableaux and representations of diagram algebras

The partition algebra is an associative algebra with a basis of set-partition diagrams and multiplication given by diagram concatenation. It contains as subalgebras a large class of diagram algebras including the Brauer, planar partition, rook monoid, rook-Brauer, Temperley-Lieb, Motzkin, planar rook monoid, and symmetric group algebras. We give a construction of the irreducible modules of these algebras in two isomorphic ways: first, as the span of symmetric diagrams on which the algebra acts by conjugation twisted with an irreducible symmetric group representation and, second, on a basis indexed by set-partition tableaux such that diagrams in the algebra act combinatorially on tableaux. The first representation is analogous to the Gelfand model and the second is a generalization of Young's natural representation of the symmetric group on standard tableaux. The methods of this paper work uniformly for the partition algebra and its diagram subalgebras. As an application, we express the characters of each of these algebras as nonnegative integer combinations of symmetric group characters whose coefficients count fixed points under conjugation