Results 11 to 20 of about 199,809 (94)

Spectral asymptotics for sub-Riemannian Laplacians. I: quantum ergodicity and quantum limits in the 3D contact case [PDF]

open access: yes, 2017
This is the first paper of a series in which we plan to study spectral asymptotics for sub-Riemannian Laplacians and to extend results that are classical in the Riemannian case concerning Weyl measures, quantum limits, quantum ergodicity, quasi-modes ...
de Verdière, Yves Colin   +2 more
core   +3 more sources

Commutators of Littlewood-Paley gκ∗$g_{\kappa}^{*} $-functions on non-homogeneous metric measure spaces

open access: yesOpen Mathematics, 2017
The main purpose of this paper is to prove that the boundedness of the commutator Mκ,b∗$\mathcal{M}_{\kappa,b}^{*} $ generated by the Littlewood-Paley operator Mκ∗$\mathcal{M}_{\kappa}^{*} $ and RBMO (μ) function on non-homogeneous metric measure ...
Lu Guanghui, Tao Shuangping
doaj   +1 more source

A unified mode decomposition method for physical fields in homogeneous cosmology [PDF]

open access: yes, 2013
The methods of mode decomposition and Fourier analysis of classical and quantum fields on curved spacetimes previously available mainly for the scalar field on Friedman- Robertson-Walker (FRW) spacetimes are extended to arbitrary vector bundle fields on ...
Avetisyan, Zhirayr G.
core   +2 more sources

Renormalization group properties in the conformal sector: towards perturbatively renormalizable quantum gravity

open access: yesJournal of High Energy Physics, 2018
The Wilsonian renormalization group (RG) requires Euclidean signature. The conformal factor of the metric then has a wrong-sign kinetic term, which has a profound effect on its RG properties.
Tim R. Morris
doaj   +1 more source

Initial Conditions in String Cosmology [PDF]

open access: yes, 1998
We take a critical look at a recent conjecture concerning the past attractor in the pre-big-bang scenario. We argue that the Milne universe is unlikely to be a general past attractor for such models and support this with a number of examples.Comment: 10 ...
A. Buonanno   +31 more
core   +2 more sources

The $L^p$-diameter of the group of area-preserving diffeomorphisms of $S^2$

open access: yes, 2016
We show that for each $p \geq 1,$ the $L^p$-metric on the group of area-preserving diffeomorphisms of the two-sphere has infinite diameter. This solves the last open case of a conjecture of Shnirelman from 1985.
Brandenbursky, Michael, Shelukhin, Egor
core   +1 more source

A two measure model of dark energy and dark matter

open access: yes, 2012
In this work we construct a unified model of dark energy and dark matter. This is done with the following three elements: a gravitating scalar field, phi with a non-conventional kinetic term, as in the string theory tachyon; an arbitrary potential, V(phi)
Douglas Singleton   +12 more
core   +1 more source

Isodiametric inequality in Carnot groups

open access: yes, 2010
The classical isodiametric inequality in the Euclidean space says that balls maximize the volume among all sets with a given diameter. We consider in this paper the case of Carnot groups.
Rigot, Severine
core   +4 more sources

Global, Local and Vector-Valued Tb Theorems on Non-Homogeneous Metric Spaces [PDF]

open access: yes, 2011
Various Tb theorems play a key role in the modern harmonic analysis. They provide characterizations for the boundedness of Calderón-Zygmund type singular integral operators.
Martikainen, Henri
core  

Homogeneous Modes of Cosmological Instantons

open access: yes, 2000
We discuss the O(4) invariant perturbation modes of cosmological instantons. These modes are spatially homogeneous in Lorentzian spacetime and thus not relevant to density perturbations.
A. Khvedelidze   +21 more
core   +1 more source

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