Discussion

More informal discussion will take place on Wednesday's at 12:30 (*and occasionally during our Tues. or Thurs. slots depending on scheduling issues) in the small seminar room. The schedule is tentative; as members decide something is more interesting or urgent, or as there are new developments, topics and facilitators may change.

Sept. 6: Eva Silverstein and Michael Dine lead a discussion on non-supersymmetric states in the landscape.

change process in string theory, connecting Calabi-Yau manifolds in a new way using non-abelian gauged linear sigma models. existing models of compactification on Riemann surfaces of arbitary genus, with fluxes and branes (including triple intersections of 7-branes (and separated anti-7-branes), which provide the necessary negative terms in the potential, locally as in Giddings/Kachru/Polchinski). This highlights the question of whether any purely ``top down" preference for supersymmetry can be determined from string theory, since tori, Calabi-Yaus, and other spaces preserving SUSY constitute a special choice among potential compactification manifolds. More formally, the larger class manifests interesting conceptual features of its own; for example using modular invariance the effective central charge of superstring theory on target spaces of negative sectional curvature can be seen to be greater than the critical value, with the fundamental group supporting an exponential density of winding modes. (This reproduces physically a basic theorem of Milnor relating topology and geometry.) Topology changing transitions connect different genera, fitting this class into the M theory hedgehog. Throughout there was discussion on various aspects and implications of this, and on the general question of how to formulate the early time behavior of such models (these, as well as Calabi-Yaus with flux), which carry positive potential energy. There will be discussions on formulating eternal inflation later in the workshop (see below). hope to have a technical seminar on this new construction somewhat later in the workshop.
 * Morrison introduced a recent paper of Hori and Tong exhibiting a new kind of classical topology
 * Silverstein discussed the likelihood that there are vast numbers of non-supersymmetric states, using as illustration
 * Dine noted that one can construct (tachyon free) models with susy broken at the compactification scale whenever one can mod out a supersymmetric compactification by a freely-acting discrete R symmetry. This allows construction of infinite sets as in IIA. We

Sept. 13: Gordy Kane leads a discussion on LHC and String Theory: what will we learn, how can we connect this to an underlying microscopic theory.

Sept. 20: Mirjam Cvetic will lead a discussion on open problems in string model building.

Sept. 27: Continuation of last week's discussion

Oct 4: Jason Kumar will lead a discussion on Baryogenesis and string theory.

Oct 25: Joe Polchinski will lead a discussion on cosmology with a focus on ``Eternal Inflation".

Nov. 1: Seminar by Michael Douglas, ``Computing Kahler Potentials in N=1 Compactifications"

Nov. 15: Segei Gukov will lead a discussion on "Elements of G2 Phenomenology".