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Given a closed contact 3-manifold with a compatible Riemannian metric, we show that if the sectional curvature is 1/4-pinched, then the contact structure is universally tight. This result improves the Contact Sphere Theorem in [EKM12],…

Differential Geometry · Mathematics 2013-04-19 Jian Ge , Yang Huang

We introduce some new curvature quantities such as conformal Ricci curvature and bi-Ricci curvature and extend the classical Myers theorem under these new curvature conditions. Moreover, we are able to obtain the Myers type theorem for…

dg-ga · Mathematics 2008-02-03 Ying Shen , Rugang Ye

A theorem of Mumford states that, on complex surfaces, any normal isolated singularity whose link is diffeomorphic to a sphere is actually a smooth point. While this property fails in higher dimensions, McLean asks whether the contact…

Algebraic Geometry · Mathematics 2017-01-24 Tommaso de Fernex , Yu-Chao Tu

First we confirm a conjecture asserting that any compact K\"ahler manifold $N$ with $\Ric^\perp>0$ must be simply-connected by applying a new viscosity consideration to Whitney's comass of $(p, 0)$-forms. Secondly we prove the projectivity…

Differential Geometry · Mathematics 2020-09-23 Lei Ni

We recast the soft $S$-matrices on the celestial sphere as correlation functions of certain $2$-dimensional models of topological defects. In pointing out the double copy structure between the soft photon and soft graviton cases, we arrive…

High Energy Physics - Theory · Physics 2021-04-27 Nikhil Kalyanapuram

We propose a new graph kernel for graph classification and comparison using Ollivier Ricci curvature. The Ricci curvature of an edge in a graph describes the connectivity in the local neighborhood. An edge in a densely connected…

Machine Learning · Computer Science 2019-07-17 Kin Sum Liu , Chien-Chun Ni , Yu-Yao Lin , Jie Gao

Soft uniform structures provide a way to speak about uniform closeness in a parameterized setting. Working over a fixed parameter set, we treat entourages as soft relations and introduce a notion of \emph{soft uniformity} whose axioms…

General Topology · Mathematics 2026-02-24 S. Ray

We discuss recursion relations for scattering amplitudes with massive particles of any spin. They are derived via a two-parameter shift of momenta, combining a BCFW-type spinor shift with the soft limit of a massless particle involved in…

High Energy Physics - Theory · Physics 2023-01-11 Adam Falkowski , Camila S. Machado

We introduce the weighted orthogonal Ricci curvature -- a two-parameter version of Ni--Zheng's orthogonal Ricci curvature. This curvature serves as a very natural object in the study of the relationship between the Ricci curvature(s) and…

Differential Geometry · Mathematics 2021-11-02 Kyle Broder , Kai Tang

The study of the quantization of the QCD string with the helix structure is put into the context of a decades-long discussion opposing the probabilistic and the deterministic interpretations of the quantum theory. The recent evolution of…

High Energy Physics - Phenomenology · Physics 2017-01-11 Sarka Todorova-Nova

Scalar effective field theories with enhanced soft limits behave in many ways like gauge theories and gravity. In particular, symmetries fix the structure of interactions and the tree-level S-matrix in both types of theories. We explore how…

High Energy Physics - Theory · Physics 2020-10-08 James Bonifacio , Kurt Hinterbichler , Laura A. Johnson , Austin Joyce , Rachel A. Rosen

Using deformation theory of rational curves, we prove a conjecture of Sommese on the extendability of morphisms from ample subvarieties when the morphism is a smooth (or mildly singular) fibration with rationally connected fibers. We apply…

Algebraic Geometry · Mathematics 2020-11-23 Tommaso de Fernex , Chung Ching Lau

In various articles, it is said that the class of all soft topologies on a common universe forms a complete lattice, but in this paper, we prove that it is a complete lattice. Some soft topologies are maximal and some are minimal with…

General Topology · Mathematics 2022-10-18 Samer Al Ghour , Zanyar A. Ameen

In a previous paper, we proved that a projective K\"ahler manifold of positive total scalar curvature is uniruled. At the other end of the spectrum, it is a well-known theorem of Campana and Koll\'ar-Miyaoka-Mori that a projective K\"ahler…

Algebraic Geometry · Mathematics 2015-09-08 Gordon Heier , Bun Wong

We describe a few elementary aspects of the circle of ideas associated with a quantum field theory (QFT) approach to Riemannian Geometry, a theme related to how Riemannian structures are generated out of the spectrum of (random or quantum)…

Mathematical Physics · Physics 2021-02-02 Mauro Carfora , Francesca Familiari

Soft theorems describe the behavior of scattering amplitudes when one or several external particles are taken to be energetically soft. In tree-level gravity there are universal soft theorems for the three leading orders in the soft…

High Energy Physics - Theory · Physics 2025-04-24 Eivind Jørstad , Sruthi A. Narayanan

We apply Tian's method in Kahler-Einstein problem to prove that a conic K\''ahler metric with lower Ricci curvature bound can be approximated by smooth K\''ahler metrics with the same lower Ricci curvature bound. Furthermore, conic…

Differential Geometry · Mathematics 2016-09-07 Liangming Shen

We prove that if the initial hypersurface of the mean curvature flow in spheres satisfies a sharp pinching condition, then the solution of the flow converges to a round point or a totally geodesic sphere. Our result improves the famous…

Differential Geometry · Mathematics 2015-06-16 Li Lei , Hongwei Xu

This is a survey paper focusing on the interplay between the curvature and topology of a Riemannian manifold. The first part of the paper provides a background discussion, aimed at non-experts, of Hopf's pinching problem and the Sphere…

Differential Geometry · Mathematics 2010-06-01 S. Brendle , R. M. Schoen

In a recent paper, Chiney and Samanta have introduced a new definition of soft topology, using the soft elementary intersection and union. In this paper, basing at this approach, we introduce a definition of soft elementary compact set, and…

General Mathematics · Mathematics 2018-05-22 Mahmoud Bousselsal , Abderachid Saadi