On simply connected five manifolds Sasakian-Einstein metrics coincide with Riemannian metrics admitting real Killing spinors which are of great interest as models of near horizon geometry for three-brane solutions in superstring theory [24]. We expand on the recent work of Demailly and Kollar [14] and Johnson and Kollar [20] who give methods for constructing Kahler-Einstein metrics on log del Pezzo surfaces. By a previous result of the first two authors [9], circle V-bundles over log del Pezzo surfaces with Kahler-Einstein metrics have Sasakian-Einstein metrics on the total space of the bundle. Here these simply connected 5-manifolds arise as links of isolated hypersurface singularities which by the well known work of Smale [36] together with [11] must be diffeomorphic to S5#l(S2×S3). More precisely, using methods from Mori theory in algebraic geometry we prove the existence of 14 inequivalent Sasakian-Einstein structures on S2×S3 and infinite families of such structures on #l(S2×S3) with 2≤l≤7. We also discuss the moduli problem for these Sasakian-Einstein structures.

background

Einstein manifolds with zero Ricci curvature

On the geometry of Sasakian-Einstein 5-manifolds

These notes are based on the Fermi Lectures delivered at the Scuola Normale Superiore, Pisa, in June 2001. The principal aim of the lectures was to present the structure theory developed by Toby Colding and myself, for metric spaces which are Gromov-Hausdorff limits of sequences of Riemannian manifolds which satisfy a uniform lower bound of Ricci curvature. The emphasis in the lectures was on the "non-collapsing" situation. A particularly interesting case is that in which the manifolds in question are Einstein (or Kahler-Einstein). Thus, the theory provides information on the manner in which Einstein metrics can degenerate.

Degeneration of Riemannian metrics under Ricci curvature bounds

On simply connected five manifolds Sasakian-Einstein metrics coincide with Riemannian metrics admitting real Killing spinors which are of great interest as models of near horizon geometry for three-brane solutions in superstring theory [KW]. We expand on the recent work of Demailly and Kollar [DK] and Johnson and Kollar [JK1] who give methods for constructing Kahler-Einstein metrics on log del Pezzo surfaces. By [BG1] circle V-bundles over log del Pezzo surfaces with Kahler-Einstein metrics have Sasakian-Einstein metrics on the total space of the bundle. Here these simply connected 5-manifolds arise as links of isolated hypersurface singularities which by the well known work of Smale [Sm] together with [BG3] must be diffeomorphic to $\scriptstyle{S^5#l(S^2\times S^3)}.$ More precisely, using methods from Mori theory in algebraic geometry we prove the existence of 14 inequivalent Sasakian-Einstein structures on $\scriptstyle{S^2\times S^3}$ and infinite families of such structures on $\scriptstyle{#l(S^2\times S^3)}$ with $\scriptstyle{2\leq l\leq7}$. We also discuss the moduli problem for these Sasakian-Einstein structures.

On the Geometry of Sasakian-Einstein 5-Manifolds

In this paper, we study the behavior of Ricci-flat Kahler metrics on Calabi-Yau manifolds under algebraic geometric surgeries: extremal transitions or flops. We prove a version of Candelas and de la Ossa’s conjecture: Ricci-flat Calabi-Yau manifolds related by extremal transitions and flops can be connected by a path consisting of continuous families of Ricci-flat Calabi-Yau manifolds and a compact metric space in the Gromov-Hausdorff topology. In an essential step of the proof of our main result, the convergence of Ricci-flat Kahler metrics on Calabi-Yau manifolds along a smoothing is established, which can be of independent interest.

/pdf/continuity-of-extremal-transitions-and-flops-for-calabi-yau-4llptfudan.pdf

Continuity of extremal transitions and flops for Calabi-Yau manifolds

Convergence of Calabi–Yau manifolds

https://www.intlpress.com/site/pub/files/_fulltext/journals/sdg/2001/0006/0001/SDG-2001-0006-0001-a001.pdf

Einstein manifolds with zero Ricci curvature

Citations

On the geometry of Sasakian-Einstein 5-manifolds

Degeneration of Riemannian metrics under Ricci curvature bounds

On the Geometry of Sasakian-Einstein 5-Manifolds

Continuity of extremal transitions and flops for Calabi-Yau manifolds

Convergence of Calabi–Yau manifolds

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