Bulletin of the American Physical Society
2008 APS April Meeting and HEDP/HEDLA Meeting
Volume 53, Number 5
Friday–Tuesday, April 11–15, 2008; St. Louis, Missouri
Session W11: Particle and String Theory |
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Sponsoring Units: DPF Chair: Sherwin Love, Purdue University Room: Hyatt Regency St. Louis Riverfront (formerly Adam's Mark Hotel), St. Louis B |
Tuesday, April 15, 2008 10:45AM - 10:57AM |
W11.00001: Heterotic Phenomenology of $SU(3)$ Manifolds Tibra Ali, Gerald Cleaver Incorporating the effects of flux compactifications, such as moduli fixing and supersymmetry breaking, in the $E_8\times E_8$ heterotic string theory is an important problem both from the theoretical and phenomenological points of view. Since there is a dearth of fluxes in heterotic strings, one way of including fluxes is by considering the internal manifold to be a six dimensional $SU(3)$ manifold. In this talk we focus mainly on a subclass of $SU(3)$ manifolds known as half-flat manifolds. First we consider the ten dimensional solution of the form $R^{1,2} \times Z_7$, where $R^{1,2}$ is a three dimensional Minkowski space-time and $Z_7$ is a non-compact $G_2$ holonomy manifold. Half-flat manifolds can be thought of as hypersurfaces in $Z_7$, and the above construction then implies that the four dimensional effective action that follows from compactification on a half-flat manifold breaks the $E_8\times E_8$ group down to $E_6\times E_8$, as in the standard embedding on Calabi-Yau compactifications. Recently, this result was also found by Gurrieri, Lukas and Micu independently using a different approach. In this talk we shall present aspects of the low-energy effective action emphasizing the ten dimensional geometric origin. We shall conclude by mentioning some observations about extending our methods and results to more general $SU(3)$ manifolds. [Preview Abstract] |
Tuesday, April 15, 2008 10:57AM - 11:09AM |
W11.00002: Heterotic String Models with Perturbatively Broken Supersymmetry? Gerald Cleaver, Alon Faraggi, Elisa Manno, Cristina Timirgaziu By employing our standard analysis of flat directions we present a quasi-realistic three generation free fermionic heterotic string model in which an F- and D- flat solution does not appear to exist at least to eighth order in the superpotential. Our analysis suggests that stringent flat directions may not exist to any order. Bose-Fermi degeneracy of the string spectrum implies that the one-loop partition function and hence the one-loop cosmological constant vanishes in the model. Hence this model may represent the first known example with vanishing cosmological constant and perturbatively broken supersymmetry. We discuss the distinctive properties of the internal free fermion boundary conditions that may correspond to a large set of models that share these properties. [Preview Abstract] |
Tuesday, April 15, 2008 11:09AM - 11:21AM |
W11.00003: Abelian fibrations, string junctions and type IIA duals of $T^6/Z_2$ Michael Schulz, Ron Donagi, Peng Gao In previous work, it was argued that the type IIB $T^6/Z_2$ orientifold with a choice of flux preserving $N=2$ supersymmetry is dual to a class of purely geometric type IIA compactifications on abelian surface ($T^4$) fibered Calabi-Yau manifolds. In this talk, I provide two concrete descriptions of the resulting manifolds. The first is a monodromy based description, which generalizes the F-theory technology of 7-branes and string junctions to the case of a $T^4$ rather than $T^2$ fiber. The second is an explicit algebro-geometric construction which the $T^4$ fibers arise as the Jacobian tori of a family of genus-2 Riemann surfaces. After describing some applications of this work, I close with a speculation on a relation between the latter construction and the dimensional duality of Silverstein et al. [Preview Abstract] |
Tuesday, April 15, 2008 11:21AM - 11:33AM |
W11.00004: Physics and Geometry of Brane Vectors Chi Xiong, Tom Clark, Sherwin Love, Tonnis ter Veldhuis In the flexible brane world scenario we use the decomposition of higher dimensional gravity and Kaluza-Klein theories to explore the properties of extra vectors. These vectors were components of higher dimensional metric and are massive due to a Higgs effect which makes the Nambu Goldstone bosons become the longitudinal component of the vector fields. We study the masses of these vectors and their couplings to the Standard Model, by using the embedding geometry. In 5D spacetime we found that the geometry of the brane-bulk world, either intrinsic or extrinsic, depend on the extra vector and the 4D graviton only. Connections between the embedding geometry and coset construction by non-linear realization are also discussed. [Preview Abstract] |
Tuesday, April 15, 2008 11:33AM - 11:45AM |
W11.00005: Bjorken flow from an AdS Schwarzschild black hole James Alsup, George Siopsis We consider a large black hole in asymptotically AdS spacetime of arbitrary dimension with a Minkowski boundary. By performing an appropriate slicing as we approach the boundary, we obtain via holographic renormalization a gauge theory fluid obeying Bjorken hydrodynamics in the limit of large longitudinal proper time. The metric we obtain reproduces to leading order the metric recently found as a direct solution of the Einstein equations in five dimensions. Our results are also in agreement with recent exact results in three dimensions. [Preview Abstract] |
Tuesday, April 15, 2008 11:45AM - 11:57AM |
W11.00006: Quasi-normal modes of a black hole localized on a brane Usama al-Binni, George Siopsis Black holes residing on a brane are expected to be observed at the LHC pointing to the existence of large extra dimensions. Signatures include the spectrum of Hawking radiation and quasi-normal modes through the detection of decay products. We calculate analytically the quasi-normal modes of black holes at the LHC using the WKB approximation. Unlike previous calculations, where the tension of the brane was assumed to be negligible, we obtain analytic expressions which are valid for any value of the tension of the brane (low as well as high). [Preview Abstract] |
Tuesday, April 15, 2008 11:57AM - 12:09PM |
W11.00007: Charged Black Hole in a Canonical Ensemble Andrew Lundgren We consider the thermodynamics of a charged black hole enclosed in a cavity. The charge in the cavity and the temperature at the walls are fixed, yielding a canonical ensemble. We derive the phase structure and stability of the black hole equilibrium states. We compare our results to those of other work which uses asymptotically anti-deSitter boundary conditions to define the thermodynamics. The thermodynamic properties have extensive similarities which suggest that the idea of AdS holography is more dependent on the existence of the boundary than on the exact details of asymptotically AdS metrics. [Preview Abstract] |
Tuesday, April 15, 2008 12:09PM - 12:21PM |
W11.00008: A Simple Model to Solve $\mu/B_\mu$ Problem in Gauge Mediation Tao Liu, Carlos Wagner We provide a simple model to solve $\mu/B_\mu$ problem in gauge mediated NMSSM. In this model the messenger sector contains one pair $3+\bar 3$ and one pair $2+\bar 2$ messengers. These two messenger pairs couple to different gauge singlets which measure SUSY breaking in the hidden sector. Such a messenger sector naturally arises in many backgrounds. We illustrate that the electroweak scale can be stabilized and phenomenologically interesting mass spectrum of particles and superparticles can be generated in most of the perturbative (at GUT scale) $\lambda-\kappa$ parameter region. In particular, this conclusion applies to all low-, intermediate- and high-scale gauge-mediations. [Preview Abstract] |
Tuesday, April 15, 2008 12:21PM - 12:33PM |
W11.00009: Chiral Lattice Gauge Theories and the Strong Coupling Dynamics of a Yukawa-Higgs Model with Ginsparg-Wilson Fermions Joel Giedt, Erich Poppitz The Yukawa-Higgs/Ginsparg-Wilson-fermion construction of chiral lattice gauge theories described in hep-lat/0605003 uses exact lattice chirality to decouple the massless chiral fermions from a mirror sector, whose strong dynamics is conjectured to give cutoff-scale mass to the mirror fermions without breaking the chiral gauge symmetry. In this talk, we report on our study of the mirror sector dynamics of a two-dimensional chiral gauge theory in the limit of strong Yukawa and vanishing gauge couplings, in which case it reduces to an $XY$ model coupled to Ginsparg-Wilson fermions. For the mirror fermions to acquire cutoff-scale mass it is believed to be important that the $XY$ model remain in its ``high temperature'' phase, where there is no algebraic ordering---a conjecture supported by the results of our work. We use analytic and Monte-Carlo methods with dynamical fermions to study the scalar and fermion susceptibilities, and the mirror fermion spectrum. Our results provide convincing evidence that the strong dynamics does not ``break" the chiral symmetry (more precisely, that the mirror fermions do not induce algebraic ordering in two-dimensions), and that the mirror fermions decouple from the infrared physics. [Preview Abstract] |
Tuesday, April 15, 2008 12:33PM - 12:45PM |
W11.00010: Symmetries in Evolving Space Time, and Their Connection to High Frequency Gravity Wave Production Andrew Beckwith We claim that linking a shrinking prior universe via a wormhole solution for a pseudo time dependent Wheeler De Witt equation permits the formation of a short-term quintessence scalar field, which is tied to an initial configuration of the Einstein field equations allowing for high frequency gravitational waves (HFGW) at the onset of inflation. This is due to symmetries in space time which enable the creation of high frequency gravitational waves. The wormhole thermal bridge between prior to present universes is of less than Planck's time duration, yet has consequences up to our present cosmological era. It also leads to phase transition changes which form a template as to graviton production. [Preview Abstract] |
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