Superpotential

About: Superpotential is a research topic. Over the lifetime, 3836 publications have been published within this topic receiving 137867 citations.

A Symplectic Hamiltonian derivation of quasilocal energy momentum for GR

Abstract: The various roles of boundary terms in the gravitational Lagrangian and Hamiltonian are explored. A symplectic Hamiltonian-boundary-term approach is ideally suited for a large class of quasilocal energy-momentum expressions for general relativity. This approach provides a physical interpretation for many of the well-known gravitational energy-momentum expressions including all of the pseudotensors, associating each with unique boundary conditions. From this perspective we find that the pseudotensors of Einstein and M{\o}ller (which is closely related to Komar's superpotential) are especially natural, but the latter has certain shortcomings. Among the infinite possibilities, we found that there are really only two Hamiltonian-boundary-term quasilocal expressions which correspond to {\em covariant} boundary conditions; they are respectively of the Dirichlet or Neumann type. Our Dirichlet expression coincides with the expression recently obtained by Katz and coworkers using Noether arguments and a fixed background. A modification of their argument yields our Neumann expression.

Matrix Models, Topological Strings, and Supersymmetric Gauge Theories

Abstract: We show that B-model topological strings on local Calabi-Yau threefolds are large N duals of matrix models, which in the planar limit naturally give rise to special geometry. These matrix models directly compute F-terms in an associated N=1 supersymmetric gauge theory, obtained by deforming N=2 theories by a superpotential term that can be directly identified with the potential of the matrix model. Moreover by tuning some of the parameters of the geometry in a double scaling limit we recover (p,q) conformal minimal models coupled to 2d gravity, thereby relating non-critical string theories to type II superstrings on Calabi-Yau backgrounds.

Anisotropic Modulus Stabilisation: Strings at LHC Scales with Micron-sized Extra Dimensions

Abstract: We construct flux-stabilised IIB compactifications whose extra dimensions (EDs) have very different sizes, and use these to describe several vacua with a TeV string scale. Because we can access regimes where 2 dimensions are hierarchically larger than the other 4, we find examples where 2 dimensions are micron-sized while the other 4 are at the weak scale in addition to standard examples with all 6 EDs equally large. Besides providing UV completeness, the phenomenology of these models is richer than vanilla large-dimensional models in several ways: (i) they are supersymmetric, with SUSY broken at sub-eV scales in the bulk but only nonlinearly realised in the SM sector, leading to no MSSM superpartners and many more bulk missing-energy channels, as in supersymmetric large extra dimensions (SLED); (ii) small cycles in the complicated extra-dimensional geometry allow some KK states to reside at TeV scales even if all 6 EDs are much larger; (iii) a rich spectrum of string and KK states at TeV scales; and (iv) an equally rich spectrum of light moduli having unusually small (but technically natural) masses, with potentially interesting implications for cosmology and astrophysics that nonetheless evade new-force constraints. The hierarchy problem is solved because the extra-dimensional volume is naturally stabilised at exponentially large values: the EDs are CY geometries with a 4D K3 or T^4-fibration over a 2D base, with moduli stabilised within the LARGE-Volume scenario. The new technical step is the use of poly-instanton corrections to the superpotential (which, unlike for simpler models, are likely to be present on K3 or T^4-fibered CY compactifications) to obtain a large hierarchy between the sizes of different dimensions. For several scenarios we identify the low-energy spectrum and briefly discuss some of their astrophysical, cosmological and phenomenological implications.

D-brane superpotentials and RG flows on the quintic

Abstract: The behaviour of D2-branes on the quintic under complex structure deformations is analysed by combining Landau-Ginzburg techniques with methods from conformal field theory. It is shown that the boundary renormalisation group flow induced by the bulk deformations is realised as a gradient flow of the effective space time superpotential which is calculated explicitly to all orders in the boundary coupling constant.