255 research outputs found
Gravitational multipole moments from Noether charges
We define the mass and current multipole moments for an arbitrary theory of
gravity in terms of canonical Noether charges associated with specific residual
transformations in canonical harmonic gauge, which we call multipole
symmetries. We show that our definition exactly matches Thorne's mass and
current multipole moments in Einstein gravity, which are defined in terms of
metric components. For radiative configurations, the total multipole charges --
including the contributions from the source and the radiation -- are given by
surface charges at spatial infinity, while the source multipole moments are
naturally identified by surface integrals in the near-zone or, alternatively,
from a regularization of the Noether charges at null infinity. The conservation
of total multipole charges is used to derive the variation of source multipole
moments in the near-zone in terms of the flux of multipole charges at null
infinity.Comment: v1: 22 pages + 13 pages of appendices, 1 figure; v2: published
version in JHE
Near Horizon Extremal Geometry Perturbations: Dynamical Field Perturbations vs. Parametric Variations
In arXiv:1310.3727 we formulated and derived the three universal laws
governing Near Horizon Extremal Geometries (NHEG). In this work we focus on the
Entropy Perturbation Law (EPL) which, similarly to the first law of black hole
thermodynamics, relates perturbations of the charges labeling perturbations
around a given NHEG to the corresponding entropy perturbation. We show that
field perturbations governed by the linearized equations of motion and symmetry
conditions which we carefully specify, satisfy the EPL. We also show that these
perturbations are limited to those coming from difference of two NHEG solutions
(i.e. variations on the NHEG solution parameter space). Our analysis and
discussions shed light on the "no-dynamics" statements of arXiv:0906.2380 and
arXiv:0906.2376.Comment: 38 page
Extremal Rotating Black Holes in the Near-Horizon Limit: Phase Space and Symmetry Algebra
We construct the NHEG phase space, the classical phase space of Near-Horizon
Extremal Geometries with fixed angular momenta and entropy, and with the
largest symmetry algebra. We focus on vacuum solutions to dimensional
Einstein gravity. Each element in the phase space is a geometry with
isometries which has vanishing and constant charges. We construct an on-shell vanishing symplectic
structure, which leads to an infinite set of symplectic symmetries. In four
spacetime dimensions, the phase space is unique and the symmetry algebra
consists of the familiar Virasoro algebra, while in dimensions the
symmetry algebra, the NHEG algebra, contains infinitely many Virasoro
subalgebras. The nontrivial central term of the algebra is proportional to the
black hole entropy. This phase space and in particular its symmetries might
serve as a basis for a semiclassical description of extremal rotating black
hole microstates.Comment: Published in PLB, 5 page
Symplectic and Killing Symmetries of AdS Gravity: Holographic vs Boundary Gravitons
The set of solutions to the AdS Einstein gravity with Brown-Henneaux
boundary conditions is known to be a family of metrics labeled by two arbitrary
periodic functions, respectively left and right-moving. It turns out that there
exists an appropriate presymplectic form which vanishes on-shell. This promotes
this set of metrics to a phase space in which the Brown-Henneaux asymptotic
symmetries become symplectic symmetries in the bulk of spacetime. Moreover, any
element in the phase space admits two global Killing vectors. We show that the
conserved charges associated with these Killing vectors commute with the
Virasoro symplectic symmetry algebra, extending the Virasoro symmetry algebra
with two generators. We discuss that any element in the phase space
falls into the coadjoint orbits of the Virasoro algebras and that each orbit is
labeled by the Killing charges. Upon setting the right-moving function
to zero and restricting the choice of orbits, one can take a near-horizon
decoupling limit which preserves a chiral half of the symplectic symmetries.
Here we show two distinct but equivalent ways in which the chiral Virasoro
symplectic symmetries in the near-horizon geometry can be obtained as a limit
of the bulk symplectic symmetries.Comment: 39 pages, v2: a reference added, the version to appear in JHE
Wiggling Throat of Extremal Black Holes
We construct the classical phase space of geometries in the near-horizon
region of vacuum extremal black holes as announced in [arXiv:1503.07861].
Motivated by the uniqueness theorems for such solutions and for perturbations
around them, we build a family of metrics depending upon a single periodic
function defined on the torus spanned by the isometry directions. We
show that this set of metrics is equipped with a consistent symplectic
structure and hence defines a phase space. The phase space forms a
representation of an infinite dimensional algebra of so-called symplectic
symmetries. The symmetry algebra is an extension of the Virasoro algebra whose
central extension is the black hole entropy. We motivate the choice of
diffeomorphisms leading to the phase space and explicitly derive the symplectic
structure, the algebra of symplectic symmetries and the corresponding conserved
charges. We also discuss a formulation of these charges with a Liouville type
stress-tensor on the torus defined by the isometries and outline
possible future directions.Comment: 56 pages, 3 figure
Crystal structure of 4,4-dimethyl-2-(trifluoromethyl)-4,5-dihydro-1H-imidazole, C6H9F3N2
C6H9F3N2, monoclinic, P21/n (no. 14), a = 10.6224(9) Å, b = 11.8639(9) Å, c = 13.3139(11) Å, β = 105.903(3)°, V = 1613.6(2) Å3, Z = 8, Rgt(F) = 0.0618, wRref(F2) = 0.1629, T = 102(2) K [1–3]
Soft Charges and Electric-Magnetic Duality
The main focus of this work is to study magnetic soft charges of the four
dimensional Maxwell theory. Imposing appropriate asymptotic falloff conditions,
we compute the electric and magnetic soft charges and their algebra both at
spatial and at null infinity. While the commutator of two electric or two
magnetic soft charges vanish, the electric and magnetic soft charges satisfy a
complex current algebra. This current algebra through Sugawara
construction yields two Kac-Moody algebras. We repeat the charge
analysis in the electric-magnetic duality-symmetric Maxwell theory and
construct the duality-symmetric phase space where the electric and magnetic
soft charges generate the respective boundary gauge transformations. We show
that the generator of the electric-magnetic duality and the electric and
magnetic soft charges form infinite copies of algebra. Moreover, we
study the algebra of charges associated with the global Poincar\'e symmetry of
the background Minkowski spacetime and the soft charges. We discuss physical
meaning and implication of our charges and their algebra.Comment: 41 pages, 4 figures; published version in JHE
Oro-Dental Health Status and Salivary Characteristics in Children with Chronic Renal Failure
Children suffering from decreased renal function may demand unique considerations regarding special oral and dental conditions they are encountered to. It is mentioned that renal function deterioration may affect the hard or soft tissues of the mouth. Having knowledge about the high prevalence of dental defects, calculus, gingival hyperplasia, modified salivary composition and tissue responses to the dental plaque may aid the physician and the dentist to help nurture the patient with chronic renal failure through the crisis, with an aesthetically satisfying and functioning dentition
- …