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We establish a short-time existence theory for complete Ricci flows under scaling-invariant curvature bounds, starting from rotationally symmetric metrics on $\mathbb{R}^{n+1}$ that are noncollapsed at infinity, without assuming bounded…

Differential Geometry · Mathematics 2025-05-30 Ming Hsiao

Ricci flow on two dimensional surfaces is far simpler than in the higher dimensional cases. This presents an opportunity to obtain much more detailed and comprehensive results. We review the basic facts about this flow, including the…

Differential Geometry · Mathematics 2011-03-25 James Isenberg , Rafe Mazzeo , Natasa Sesum

We prove the short-time existence of Ricci flows on complete manifolds with scalar curvature bounded below uniformly, Ricci curvature bounded below by a negative quadratic function, and with almost Euclidean isoperimetric inequality holds…

Differential Geometry · Mathematics 2024-10-15 Fei He

We show for a non homogeneous boundary value problem for the Ricci flow on the disk that when the initial metric has positive curvature and the boundary is convex then the initial metric is deformed, via the normalized flow and along…

Differential Geometry · Mathematics 2016-03-11 Jean C. Cortissoz , Alexander Murcia

This is the first of a series of papers on the long-time behavior of 3 dimensional Ricci flows with surgery. In this paper we first fix a notion of Ricci flows with surgery, which will be used in this and the following three papers. Then we…

Differential Geometry · Mathematics 2018-03-16 Richard H. Bamler

A theory of gravitation is proposed, modeled after the notion of a Ricci flow. In addition to the metric an independent volume enters as a fundamental geometric structure. Einstein gravity is included as a limiting case. Despite being a…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Wolfgang Graf

The two-dimensional renormalization group acting as the Ricci flow $\Lambda\frac{\partial}{\partial\Lambda} g_{\mu\nu} = R_{\mu\nu}$ produces a specific 1+3 dimensional space-time metric which describes an expanding universe that starts…

Cosmology and Nongalactic Astrophysics · Physics 2020-05-13 Daniel Friedan

This is the second paper in a series of works devoted to nonholonomic Ricci flows. By imposing non-integrable (nonholonomic) constraints on the Ricci flows of Riemannian metrics we can model mutual transforms of generalized Finsler-Lagrange…

Differential Geometry · Mathematics 2008-11-26 Sergiu I. Vacaru

In this paper we study a boundary value problem for the Ricci flow in the two dimensional ball endowed with a rotationally symmetric metric. We show short and long time existence results. We construct families of metrics for which the flow…

Differential Geometry · Mathematics 2007-05-23 Jean Cortissoz

In this work we construct and analyze exact solutions describing Ricci flows and nonholonomic deformations of four dimensional (4D) Taub-NUT spacetimes. It is outlined a new geometric techniques of constructing Ricci flow solutions. Some…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Sergiu I. Vacaru , Mihai Visinescu

We discuss in rather general terms quantum field theories dealing with spaces of maps between Riemannian manifolds. In particular we explore the well--known connection between the renormalization group flow for non--linear sigma models and…

High Energy Physics - Theory · Physics 2015-05-13 Mauro Carfora , Stefano Romano

In this paper we present some results on a family of geometric flows introduced by Bourguignon that generalize the Ricci flow. For suitable values of the scalar parameter involved in these flows, we prove short time existence and provide…

Differential Geometry · Mathematics 2017-04-25 Giovanni Catino , Laura Cremaschi , Zindine Djadli , Carlo Mantegazza , Lorenzo Mazzieri

The renormalization group equations of two-dimensional sigma models describe geometric deformations of their target space when the world-sheet length changes scale from the ultra-violet to the infra-red. These equations, which are also…

High Energy Physics - Theory · Physics 2009-11-10 I. Bakas

In this expository article, we introduce the topological ideas and context central to the Poincare Conjecture. Our account is intended for a general audience, providing intuitive definitions and spatial intuition whenever possible. We…

History and Overview · Mathematics 2011-01-04 Scott D. Kominers

In this paper we analyze Ricci flows on which the scalar curvature is globally or locally bounded from above by a uniform or time-dependent constant. On such Ricci flows we establish a new time-derivative bound for solutions to the heat…

Differential Geometry · Mathematics 2015-11-20 Richard H. Bamler , Qi S. Zhang

Ricci flow spacetimes were introduced by Kleiner & Lott as a way to describe Ricci flow through singularities, and have since been used elsewhere in the literature, prompting the question of their rigidity. In $(2+1)$-dimensions, we show…

Differential Geometry · Mathematics 2022-11-23 Luke Thomas Peachey

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

We discuss from a geometric point of view the connection between the renormalization group flow for non--linear sigma models and the Ricci flow. This offers new perspectives in providing a geometrical landscape for 2D quantum field…

High Energy Physics - Theory · Physics 2010-01-21 Mauro Carfora

Ricci curvature and Ricci flow have proven to be powerful tools for analyzing the geometry of discrete structures, particularly on undirected graphs, where they have been applied to tasks ranging from community detection to graph…

Differential Geometry · Mathematics 2025-09-25 Shuliang Bai , Rui Li , Shuang Liu , Xin Lai

We revisit spatially flat FLRW cosmology in light of recent advances in standard model relativistic fluid dynamics. Modern fluid dynamics requires the presence of curvature-matter terms in the energy-momentum tensor for consistency. These…

General Relativity and Quantum Cosmology · Physics 2019-07-09 Rudolf Baier , Sayantani Lahiri , Paul Romatschke