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We introduce a new functional $\mathcal{E}_{\mathfrak{p}}$ on the space of conformal structures on an oriented projective manifold $(M,\mathfrak{p})$. The nonnegative quantity $\mathcal{E}_{\mathfrak{p}}([g])$ measures how much…

Differential Geometry · Mathematics 2024-10-22 Thomas Mettler

Let $\overline{M}$ be a smooth manifold with boundary $\partial M$ and interior $M$. Consider an affine connection $\nabla$ on $M$ for which the boundary is at infinity. Then $\nabla$ is projectively compact of order $\alpha$ if the…

Differential Geometry · Mathematics 2016-11-08 Andreas Cap , A. Rod Gover

We point out a simple construction of an infinite class of Einstein near-horizon geometries in all odd dimensions greater than five. Cross-sections of the horizons are inhomogeneous Sasakian metrics (but not Einstein) on S^3xS^2 and more…

High Energy Physics - Theory · Physics 2012-10-19 Hari K. Kunduri , James Lucietti

We discuss Sasakian-Einstein geometry under a quasi-regularity assumption. It is shown that the space of all quasi-regular Sasakian-Einstein orbifolds has a natural multiplication on it. Furthermore, necessary and sufficient conditions are…

Differential Geometry · Mathematics 2007-05-23 Charles P. Boyer , Krzysztof Galicki

We extend the notion of a Sasakian structure from the classical setting of a cooriented contact manifold, where it is given by a compatibility between a contact form $\eta$ and a Riemannian metric $g_M$ on $M$, to the case of an arbitrary…

Differential Geometry · Mathematics 2026-05-27 Katarzyna Grabowska , Janusz Grabowski , Rouzbeh Mohseni

We study eta-Einstein geometry as a class of distinguished Riemannian metrics on contact metric manifolds. In particular, we use a previous solution of the Calabi problem for Sasakian geometry to prove the existence of eta-Einstein…

Differential Geometry · Mathematics 2008-11-26 Charles P. Boyer , Krzysztof Galicki , Paola Matzeu

In this note we begin a systematic study of compact conformal manifolds of SCFTs in four dimensions (our notion of compactness is with respect to the topology induced by the Zamolodchikov metric). Supersymmetry guarantees that such…

High Energy Physics - Theory · Physics 2015-06-23 Matthew Buican , Takahiro Nishinaka

The purpose of this paper is to study the Sasakian geometry on odd dimensional sphere bundles over a smooth projective algebraic variety $N$ with the ultimate, but probably unachievable goal of understanding the existence and non-existence…

Differential Geometry · Mathematics 2021-09-29 Charles P. Boyer , Christina W. Tønnesen-Friedman

We propose a new approach to the existence of constant transversal scalar curvature Sasaki structures drawing on ideas and tools from the CR Yamabe problem, establishing a link between the CR Yamabe invariant, the existence of Sasaki…

Differential Geometry · Mathematics 2025-09-03 Abdellah Lahdili , Eveline Legendre , Carlo Scarpa

We establish an equivalence between conformally Einstein--Maxwell Kahler 4-manifolds (recently studied in many works) and extremal Kahler 4-manifolds (in the sense of Calabi) with nowhere vanishing scalar curvature. The corresponding pairs…

Differential Geometry · Mathematics 2019-01-07 Vestislav Apostolov , David M. J. Calderbank

We show that any dimension $6$ nearly K\"ahler (or nearly para-K\"ahler) geometry arises as a projective manifold equipped with a $\textrm{G}_2^{(*)}$ holonomy reduction. In the converse direction we show that if a projective manifold is…

Differential Geometry · Mathematics 2017-08-22 Rod Gover , Roberto Panai , Travis Willse

We develop a geometric and explicit construction principle that generates classes of Poincare-Einstein manifolds, and more generally almost Einstein manifolds. Almost Einstein manifolds satisfy a generalisation of the Einstein condition;…

Differential Geometry · Mathematics 2008-08-18 A. Rod Gover , Felipe Leitner

We introduce the concept of a branched holomorphic Cartan geometry. It generalizes to higher dimension the definition of branched (flat) complex projective structure on a Riemann surface introduced by Mandelbaum. This new framework is much…

Differential Geometry · Mathematics 2018-01-16 Indranil Biswas , Sorin Dumitrescu

Using $S^1$-equivariant symplectic homology, in particular its mean Euler characteristic, of the natural filling of links of Brieskorn-Pham polynomials, we prove the existence of infinitely many inequivalent contact structures on various…

Differential Geometry · Mathematics 2016-12-21 Charles P. Boyer , Leonardo Macarini , Otto van Koert

In the present work we provide a constructive method to describe contact structures on compact homogeneous contact manifolds. The main feature of our approach is to describe the Cartan-Ehresmann connection (gauge field) for principal circle…

Differential Geometry · Mathematics 2019-08-07 Eder M. Correa

By combining the join construction from Sasakian geometry with the Hamiltonian 2-form construction from K\"ahler geometry, we recover Sasaki-Einstein metrics discovered by physicists. Our geometrical approach allows us to give an algorithm…

Differential Geometry · Mathematics 2014-06-19 Charles P. Boyer , Christina W. Tønnesen-Friedman

We develop a holonomy reduction procedure for general Cartan geometries. We show that, given a reduction of holonomy, the underlying manifold naturally decomposes into a disjoint union of initial submanifolds. Each such submanifold…

Differential Geometry · Mathematics 2014-05-08 Andreas Cap , A. Rod Gover , Matthias Hammerl

We discuss a deformation of Sasakian structure in the presence of totally skew-symmetric torsion by introducing odd dimensional manifolds whose metric cones are K\"ahler with torsion. It is shown that such a geometry inherits similar…

High Energy Physics - Theory · Physics 2015-06-05 Tsuyoshi Houri , Hiroshi Takeuchi , Yukinori Yasui

In this article we discuss how to construct canonical \emph{strong} Carrollian geometries at time/space like infinity of projectively compact Ricci flat Einstein manifolds $(M,g)$ and discuss the links between the underlying projective…

Differential Geometry · Mathematics 2024-12-24 Jack Borthwick , Yannick Herfray

We describe a general procedure for constructing new Sasaki metrics of constant scalar curvature from old ones. Explicitly, we begin with a regular Sasaki metric of constant scalar curvature on a 2n+1-dimensional compact manifold M and…

Differential Geometry · Mathematics 2016-08-23 Charles P. Boyer , Christina W. Tønnesen-Friedman