Paper · Aug 12, 2024

The weighted Hermite–Einstein equation

Michael Hallam, Abdellah Lahdili

As on arXiv

Abstract

We introduce a new weighted version of the Hermite–Einstein equation, along with notions of weighted slope (semi/poly)stability, and prove that a vector bundle admits a weighted Hermite–Einstein metric if and only if it is weighted slope polystable. The new equation encompasses several well-known examples of canonical Hermitian metrics on vector bundles, including the usual Hermite–Einstein metrics, Kähler–Ricci solitons, and transversally Hermite–Einstein metrics on certain Sasaki manifolds. We prove that the equation arises naturally as a moment map, that solutions to the equation are unique up to scaling, and demonstrate a weighted Kobayashi–Lübke inequality satisfied by vector bundles admitting a weighted Hermite–Einstein metric. As an application of our techniques, we extend a bound of Tian on the Ricci curvature to a bound on a modified Ricci curvature, related to the existence of Kähler–Ricci solitons. Along the way, we introduce a new weighted vortex equation, as well as a weighted analogue of Gieseker stability. A key technical point is the application of a new extension of Inoue's equivariant intersection numbers to arbitrary weight functions on the moment polytope of a Kähler manifold with Hamiltonian torus action.

Submitted
Aug 12, 2024
Subjects
math.DG, math.AG

Comments: 56 pages, comments welcome

Its neighbourhood

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The 8 papers on this site closest to this one, judged by the topics they share, the words and phrases in their titles and abstracts, and their authors. They are not its citations, but a map of the work around it. Papers here go back to 2021, plus the canon.

Connected papers This paper in the centre and the 8 papers closest to it around it, in date order clockwise from the top. The closer a paper sits to the centre, the stronger the connection. This paper Multiplier Hermitian-Einstein metrics on Fano manifolds of KSM-type (Yasuhiro Nakagawa and Satoshi Nakamura, 2022)8Nakagawa 2022 Weighted extremal metrics on blowups (Michael Hallam, 2023)1Hallam 2023 Deformations of Fano manifolds with weighted solitons (Akito Futaki, 2023)2Futaki 2023 Log del Pezzo ℂ^*-surfaces, Kähler-Einstein metrics, Kähler-Ricci solitons and Sasaki-Einstein metrics (Daniel Hättig, Jürgen Hausen and Hendrik Süß, 2023)3Hättig 2023 From Kähler Ricci solitons to Calabi-Yau Kähler cones (Vestislav Apostolov, Abdellah Lahdili and Eveline Legendre, 2024)5Apostolov 2024 On weighted extremal Kähler metrics (Akito Futaki, 2026)4Futaki 2026 Sasaki with torsion manifolds and string backgrounds (Beatrice Brienza, Anna Fino, Udhav Fowdar et al., 2026)7Brienza 2026 The Miyaoka-Yau inequality and the delta invariant for Fano varieties II -soliton case- (Tomoyuki Hisamoto and Masataka Iwai, 2026)6Hisamoto 2026
Closer to the centre: more closely connected. Clockwise from the top: oldest to newest. Ricci flowWider flowsalso connected to each other
  1. Weighted extremal metrics on blowups

    Michael Hallam

    Topics Sasakian & contact geometry, Kähler–Ricci solitons, Kähler geometry · Same author Michael Hallam · Shared terms “torus action”, “Sasaki”

  2. Deformations of Fano manifolds with weighted solitons

    Akito Futaki

    Topics Sasakian & contact geometry, Kähler–Ricci solitons, Einstein metrics · Shared terms “moment polytope”, “weight functions”, “equivariant”

  3. Log del Pezzo -surfaces, Kähler-Einstein metrics, Kähler-Ricci solitons and Sasaki-Einstein metrics

    Daniel Hättig, Jürgen Hausen and Hendrik Süß

    Topics Sasakian & contact geometry, Kähler–Ricci solitons, Einstein metrics · Shared terms “Sasaki”, “admitting”

  4. On weighted extremal Kähler metrics

    Akito Futaki

    Topics Sasakian & contact geometry, Kähler–Ricci solitons, Einstein metrics · Shared terms “Sasaki”

  5. From Kähler Ricci solitons to Calabi-Yau Kähler cones

    Vestislav Apostolov, Abdellah Lahdili and Eveline Legendre

    Topics Kähler–Ricci solitons, Kähler geometry, Ricci solitons · Same author Abdellah Lahdili · Shared terms “weight functions”, “polytope”

  6. The Miyaoka-Yau inequality and the delta invariant for Fano varieties II -soliton case-

    Tomoyuki Hisamoto and Masataka Iwai

    Topics Kähler–Ricci solitons, Einstein metrics, Kähler geometry · Shared terms “weighted slope”, “equivariant”, “Gieseker”

  7. Sasaki with torsion manifolds and string backgrounds

    Beatrice Brienza, Anna Fino, Udhav Fowdar et al.

    Topics Sasakian & contact geometry, Einstein metrics, Kähler geometry · Shared terms “Hermite”, “Sasaki”, “analogue”

  8. Multiplier Hermitian-Einstein metrics on Fano manifolds of KSM-type

    Yasuhiro Nakagawa and Satoshi Nakamura

    Topics Kähler–Ricci solitons, Einstein metrics, Kähler geometry · Shared terms “Hermitian”, “admitting”

Read around it

Background reading

The guides for the topics of this paper: what each idea is, why it matters, and the papers to read first.

In the guidebook

  1. 11B.1
    Ricci SolitonsBook 11B · Solitons, Compactness and Singularities

    Self-similar solutions: the Gaussian, cylinders, the cigar and the Bryant soliton.

  2. 12B.2
    The Asymptotic Soliton and Three-Dimensional ShrinkersBook 12B · κ-Solutions and Surgery

    Perelman's Proposition 11.2 proved with Morgan and Tian: the reduced-length bounds on κ-solutions, the limit of rescalings, the equality case, and the classification of shrinking solitons in dimensions two and three.