We present a complete classification of simply-connected pluriclosed manifolds with parallel Bismut torsion. Consequently, we also establish a splitting theorem for compact manifolds that are both pluriclosed with parallel Bismut torsion and have vanishing Bismut Ricci form. Due to the relations of these conditions with the Vaisman geometry, we also analyze the behavior of the pluriclosed flow, proving that it preserves the Vaisman condition on compact complex surfaces if and only if the starting metric has constant scalar curvature.
Ricci-flat metrics are fundamental in differential geometry, and they are easier to study when they have additional structures. I will describe my works on 4d non-trivially conformally Kähler Ricci-flat metrics, which actually is a very natural class of 4d Ricci-flat metrics. This leads to a classification of asymptotic geometries of such metrics at infinity and a classification of such gravitational instantons
Kahler Gradient Ricci Solitons (KGRS) are fundamental in the theory of Ricci flows. This talk's focus is on complex dimension two and will first review the recent beautiful classification of the shrinking possibly non-compact case. Then we'll discuss an approach to detect symmetry applicable to all cases. This differs from and should complement the popular perspective based on asymptotic behaviors. The idea is inspired by Morse-theoretic aspects of symplectic geometry and involves the understanding of singular sets of a moment map. Precisely, we'll show that a KGRS in complex dimension two is an integrable Hamiltonian system; if the system is generic, then it admits a holomorphic 2-torus action.
In this joint work with Mihai Paun, we show that a so-called Q-sheaf on a log terminal Kahler threefold satisfies a suitable Bogomolov-Gieseker inequality as soon as it is stable with respect to a Kahler class. I will discuss the strategy of the proof as well as some applications if time permits.
A central theme in Kähler geometry is the search for canonical Kähler metrics, such as Kähler-Einstein metrics, constant scalar curvature Kähler (cscK for short) metrics, extremal metrics, Kähler-Ricci solutions, etc. The concept of weighted cscK metrics, introduced by Lahdili in 2019, provides a unification of all the above geometric settings. In this talk I will give a panorama of what it is known about these metrics and I will present a criteria for ensuring their existence. This is a joint work with S. Jubert and A. Lahdili.
Steady Kahler-Ricci solitons are eternal solutions of the Kahler-Ricci flow. I will present new examples of such solitons with strictly positive sectional curvature that live on C^n and provide an answer to an open question of H.-D. Cao in complex dimension 2. This is joint work with Pak-Yeung Chan and Yi Lai.
Let P be a homogeneous polynomial in N+1 complex variables of degree d. The logarithmic Mahler Measure of P (denoted by m(P) ) is the integral of log|P| over the sphere in C^{N+1} with respect to the usual Hermitian metric and measure on the sphere. Now let X be a smooth variety embedded in CP^N by a high power of an ample line bundle and let $\Delta$ denote a generalized discriminant of X wrt the given embedding , then $\Delta$ is an irreducible homogeneous polynomial in the appropriate space of variables. In this talk I will discuss work in progress whose aim is to find an asymptotic expansion of m(\Delta) in terms of elementary functions of the degree of the embedding.
Gravitational instantons are non-compact Calabi-Yau metrics with L^2 bounded curvature and are categorized into six types. We will focus on the ALH* type which has a non-compact end with inhomogeneous collapsing near infinity. I will talk about a joint project with Rafe Mazzeo on the Fredholm mapping property of the Laplacian and the Dirac operator, where the geometric microlocal analysis of fibered metrics plays a central role. Application of this Fredholm theory includes the L^2 Hodge theory, polyhomogeneous expansion and local perturbation theory. I will also discuss a joint project with Yu-Shen Lin and Sidharth Soundararajan on the degeneration of such metrics which gives a partial compactification of their moduli space.
We will discuss the isotopy problem of symplectic forms in a fixed symplectic class on compact four manifolds.
We will introduce a nonlinear Hodge flow for a general approach. We will also discuss the hypersymplectic flow, introduced by Fine-Yao to study hypersymplectic four manifolds.
We introduce a 4th order flow moving Lagrangian submanifolds in a symplectic manifold. The flow evolves within a Hamiltonian isotopy class and is a gradient flow for volume, and it exists uniquely in shorttime and can be extended if the 2nd fundamental form is bounded.
This is joint work with Micah Warren.