scholarly journals Extrinsic curvature of semiconvex subspaces in Alexandrov geometry

2009 ◽  
Vol 37 (3) ◽  
pp. 241-262 ◽  
Author(s):  
Stephanie B. Alexander ◽  
Richard L. Bishop
Keyword(s):  
Extrinsic Curvature ◽  
Alexandrov Geometry

scholarly journals HIGHER-ORDER CURVATURE TERMS IN BORN–INFELD TYPE BRANE THEORIES

2011 ◽  
Vol 20 (01) ◽  
pp. 59-75 ◽  
Author(s):  
EFRAIN ROJAS
Keyword(s):  
Ricci Tensor ◽  
General Structure ◽  
Extrinsic Curvature ◽  
Higher Order ◽  
Square Root ◽  
Auxiliary Variables ◽  
Field Equations ◽  
Alternative Description ◽  
Brane Models ◽  
Combined Matrix

The field equations associated to Born–Infeld type brane theories are studied by using auxiliary variables. This approach hinges on the fact, that the expressions defining the physical and geometrical quantities describing the worldvolume are varied independently. The general structure of the Born–Infeld type theories for branes contains the square root of a determinant of a combined matrix between the induced metric on the worldvolume swept out by the brane and a symmetric/antisymmetric tensor depending on gauge, matter or extrinsic curvature terms taking place on the worldvolume. The higher-order curvature terms appearing in the determinant form come to play in competition with other effective brane models. Additionally, we suggest a Born–Infeld–Einstein type action for branes where the higher-order curvature content is provided by the worldvolume Ricci tensor. This action provides an alternative description of the dynamics of braneworld scenarios.

COVARIANT CONFORMAL DECOMPOSITION OF EINSTEIN EQUATIONS

2002 ◽  
Vol 17 (20) ◽  
pp. 2762-2762
Author(s):  
E. GOURGOULHON ◽  
J. NOVAK
Keyword(s):  
Numerical Simulations ◽  
Extrinsic Curvature ◽  
Einstein Equations ◽  
Numerical Implementation ◽  
Einstein’S Equations ◽  
Einstein's Equations ◽  
Tensor Density ◽  
Dirac Gauge ◽  
Ill Posed ◽  
Isolated Systems

It has been shown1,2 that the usual 3+1 form of Einstein's equations may be ill-posed. This result has been previously observed in numerical simulations3,4. We present a 3+1 type formalism inspired by these works to decompose Einstein's equations. This decomposition is motivated by the aim of stable numerical implementation and resolution of the equations. We introduce the conformal 3-"metric" (scaled by the determinant of the usual 3-metric) which is a tensor density of weight -2/3. The Einstein equations are then derived in terms of this "metric", of the conformal extrinsic curvature and in terms of the associated derivative. We also introduce a flat 3-metric (the asymptotic metric for isolated systems) and the associated derivative. Finally, the generalized Dirac gauge (introduced by Smarr and York5) is used in this formalism and some examples of formulation of Einstein's equations are shown.

scholarly journals ON EIGENVALUE ESTIMATES FOR THE SUBMANIFOLD DIRAC OPERATOR

2002 ◽  
Vol 13 (05) ◽  
pp. 533-548 ◽  
Author(s):  
NICOLAS GINOUX ◽  
BERTRAND MOREL
Keyword(s):  
Dirac Operator ◽  
Lower Bounds ◽  
Dirac Operators ◽  
Extrinsic Curvature ◽  
Eigenvalue Estimates ◽  
Killing Spinors ◽  
Spinor Fields ◽  
Twisted Dirac Operators

We give lower bounds for the eigenvalues of the submanifold Dirac operator in terms of intrinsic and extrinsic curvature expressions. We also show that the limiting cases give rise to a class of spinor fields generalizing that of Killing spinors. We conclude by translating these results in terms of intrinsic twisted Dirac operators.

Anomalies generated by extrinsic curvature

1987 ◽  
Vol 36 (3) ◽  
pp. 479-486 ◽  
Author(s):  
F. Langouche ◽  
H. Leutwyler
Keyword(s):  
Extrinsic Curvature

scholarly journals Manifold curvature and Ehrenfest forces with a moving basis

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Jessica Halliday ◽  
Emilio Artacho
Keyword(s):  
Extrinsic Curvature ◽  
Quantum States ◽  
Basis Set ◽  
Electronic Subsystem ◽  
Intrinsic Curvature ◽  
Geometrical Meaning

Known force terms arising in the Ehrenfest dynamics of quantum electrons and classical nuclei, due to a moving basis set for the former, can be understood in terms of the curvature of the manifold hosting the quantum states of the electronic subsystem. Namely, the velocity-dependent terms appearing in the Ehrenfest forces on the nuclei acquire a geometrical meaning in terms of the intrinsic curvature of the manifold, while Pulay terms relate to its extrinsic curvature.

scholarly journals Submanifolds with nonpositive extrinsic curvature

2016 ◽  
Vol 196 (2) ◽  
pp. 407-426 ◽  
Author(s):  
Samuel Canevari ◽  
Guilherme Machado de Freitas ◽  
Fernando Manfio
Keyword(s):  
Extrinsic Curvature

scholarly journals A Conformal Field Theory of Extrinsic Geometry of 2-d Surfaces

1997 ◽  
Vol 52 (1-2) ◽  
pp. 97-104
Author(s):  
K.S. Viswanathan ◽  
R. Parthasarathy
Keyword(s):  
Extrinsic Curvature ◽  
Universality Class ◽  
Gravity Theory ◽  
World Sheet ◽  
Light Cone Gauge ◽  
Conformal Field ◽  
Extrinsic Geometry ◽  
Wznw Model ◽  
The Mean ◽  
Conserved Currents

Abstract In the description of the extrinsic geometry of the string world sheet regarded as a conformal immersion of a 2-d surface in R3 it was previously shown that, restricting to surfaces with h √ g = 1, where h is the mean scalar curvature and g is the determinant of the induced metric on the surface, leads to Virasaro symmetry. An explicit form of the effective action on such surfaces is constructed in this article, which is the extrinsic curvature analog of the WZNW action. This action turns our to be the gauge invariant combination of the actions encountered in 2-d intrinsic gravity theory in light-cone gauge and the geometric action appearing in the quantization of the Virasaro group. This action, besides exhibiting Virasaro symmetry in z-sector, has SL (2, C) conserved currents in the z̅-sector. This allows us to quantize this theory in the z̅-sector along the lines of the WZNW model. The quantum theory on h √ g = 1 surfaces in R3 is shown to be in the same universality class as the intrinsic 2-d gravity theory.

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