Forthcoming events in this series
The torsional conifold: fivebranes and the Klebanov-Strassler theory
Abstract
Stringy corrections to the Kahler potential, SUSY breaking and the stabilization of (all) Kahler moduli
String Theory and Many-Body Physics
Abstract
Aspects of heterotic Calabi-Yau compactifications
Abstract
Crystal Melting and Wall Crossing for Donaldson-Thomas Invariants
Abstract
On Fields over Fields
Abstract
Generalized scaling and integrability from AdS5 x S5
Abstract
N=2 Superconformal Theories and M5 branes
Abstract
Holographic Superconductors in M-Theory
Abstract
Twistor-Strings, Grassmannians and Leading Singularities
Abstract
Scanning through Heterotic Vacua
Abstract
T-Duality Invariant String Theory at the Quantum Level
Abstract
In this talk I will be discussing some reformulations of string theory which promote T-duality to the level of a manifest symmetry namely Hull's Doubled Formalism and Klimcik and Severa's Poisson-Lie T-duality. Such formalisms double the number of fields but also incorporate some chirality-like constraint. Invoking this constraint leads one to consider sigma-models which, though duality invariant, do not possess manifest Lorentz Invariance. Whilst such formalisms make sense at a classical level their quantum validity is less obvious. I address this issue by examining the renormalization of these duality invariant sigma models. This talk is based upon both forthcoming work and recent work in arXiv:0910.1345 [hep-th] and its antecedents arXiv:0708.2267, arXiv:0712.1121.
Computational Challenges in Calabi-Yau and String Phenomenology
Abstract
Three dimensional gravity, its black holes, conformal symmetry and the remarkable application of the Cardy formula
Abstract
M2-branes at hypersurface singularities and their deformations
Abstract
On the classification of Brane Tilings
Abstract
Dynamical Vacuum Selection and Supersymmetry Breaking in String Theory
Abstract
Gauge Threshold Corrections for Local String Models
Abstract
A CY Manifold with 3 Generations and Small Hodge Numbers
Abstract
String Axiverse
Abstract
String theory suggests the simultaneous presence of many ultralight axions possibly populating each decade of mass down to the Hubble scale 10^-33eV. Conversely the presence of such a plenitude of axions (an "axiverse") would be evidence for string theory, since it arises due to the topological complexity of the extra-dimensional manifold and is ad hoc in a theory with just the four familiar dimensions. We investigate how upcoming astrophysical experiments will explore the existence of such axions over a vast mass range from 10^-33eV to 10^-10eV. Axions with masses between 10^-33eV to 10^-28eV cause a rotation of the CMB polarization that is constant throughout the sky. The predicted rotation angle is of order \alpha~1/137. Axions in the mass range 10^-28eV to 10^-18eV give rise to multiple steps in the matter power spectrum, that will be probed by upcoming galaxy surveys and 21 cm line tomography. Axions in the mass range 10^-22eV to 10^-10eV affect the dynamics and gravitational wave emission of rapidly rotating astrophysical black holes through the Penrose superradiance process. When the axion Compton wavelength is of order of the black hole size, the axions develop "superradiant" atomic bound states around the black hole "nucleus". Their occupation number grows exponentially by extracting rotational energy from the ergosphere, culminating in a rotating Bose-Einstein axion condensate emitting gravitational waves. This mechanism creates mass gaps in the spectrum of rapidly rotating black holes that diagnose the presence of axions. The rapidly rotating black hole in the X-ray binary LMC X-1 implies an upper limit on the decay constant of the QCD axion f_a