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<title>Neckpinch — Scalar curvature</title><link>https://neckpinch.com/topics/scalar-curvature/</link><description>New arXiv papers on scalar curvature, from Neckpinch</description>
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<item><title>Conjugate radius and parabolicity along the Ricci flow</title><link>https://neckpinch.com/papers/2611.03823/</link><guid isPermaLink="false">arxiv:2611.03823</guid><pubDate>Mon, 02 Nov 2026 00:00:00 GMT</pubDate><description>Chandan Kumar Mondal — We study the behaviour of the conjugate radius under the Ricci flow on complete noncompact manifolds. We show that if (Mⁿ,g(t))_(t∈[0,T]) is a complete Ricci flow with nonnegative scalar curvature at t=0, the initial metric is parabolic and not Ricci-flat, and the Einstein tensor Ric-1/2 Rg is bounded above, then parabolicity is preserved along the flow and the conjugate radius of g(t) is finite for every t∈(0,T]. As an application, we prove that a complete noncompact gradient shrinking Ricci soliton whose volume growth is subquadratic, in the sense that liminf_(r→∞)Vol(B(p,r))/r²=0, has finite conjugate radius.</description><category>Ricci flow</category><category>Ricci solitons</category><category>Ricci-flat &amp; Calabi–Yau</category><category>Scalar curvature</category><category>Boundaries &amp; non-compact</category></item>
<item><title>Rigidity of shrinking Ricci solitons with low-dimensional focal sets</title><link>https://neckpinch.com/papers/2611.02740/</link><guid isPermaLink="false">arxiv:2611.02740</guid><pubDate>Mon, 02 Nov 2026 00:00:00 GMT</pubDate><description>Matheus Andrade Ribeiro de Moura Horácio — We prove that, in every dimension, the focal set of the potential function of a complete gradient shrinking Ricci soliton with constant scalar curvature is totally geodesic whenever it has dimension two or three, and that every complete five-dimensional gradient shrinking Ricci soliton with constant scalar curvature is rigid. The first result follows from a Bochner identity for the covariant derivative of the Ricci tensor at the focal set. For the second, when the scalar curvature is twice the soliton constant, we prove that total geodesy implies rigidity through an integral identity on the level hypersurfaces; the case of scalar curvature three times the soliton constant is treated by a separate argument. As further applications, we combine our methods with the rigidity theorem in the recent preprint of Li, Li, Ou, Qu, Wu and Zhou to obtain rigidity in arbitrary dimension when the scalar curvature is twice or three times the soliton constant, and under integral Weyl pinching for four-dimensional focal sets.</description><category>Ricci solitons</category><category>Curvature pinching</category><category>4-manifolds</category><category>Scalar curvature</category><category>Stability &amp; uniqueness</category></item>
<item><title>Calabi flow on polarized Kähler surfaces</title><link>https://neckpinch.com/papers/2611.01968/</link><guid isPermaLink="false">arxiv:2611.01968</guid><pubDate>Sun, 01 Nov 2026 00:00:00 GMT</pubDate><description>Haozhao Li, Bing Wang, Kai Zheng — We study global smooth Calabi flows on polarized Kähler surfaces (M,L), assuming uniformly bounded Sobolev constants and the algebraic conditions χ(𝓞_M)=1 and c₁(M)· c₁(L)&gt;0. Using the orbifold compactness theorem, we prove a uniform Bergman estimate, construct a normal test configuration for each geometric limit, and establish uniqueness of the extremal orbifold limit up to polarized holomorphic isometry. K-polystability then identifies the limit with the original surface and gives a constant scalar curvature Kähler metric. We also prove finite-group equivariant versions of these results. Independently of the flow, we obtain a uniform Bergman lower bound for polarized cscK surfaces with bounded volume and Sobolev constants and |S|≤1. We illustrate the hypotheses with nonstationary flows near a product cscK metric on ℙ¹×ℙ¹ and near Calabi&apos;s non-cscK extremal metric on the first Hirzebruch surface. Their controlled-cone energy inequalities follow from elementary calculations and continuity.</description><category>Other curvature flows</category><category>Kähler geometry</category><category>Scalar curvature</category><category>Limit spaces &amp; RCD</category><category>Stability &amp; uniqueness</category><category>Kähler–Einstein &amp; K-stability</category></item>
<item><title>Chern scalar curvature and finite-time singularities of the conformal Chern–Calabi flow</title><link>https://neckpinch.com/papers/2611.01623/</link><guid isPermaLink="false">arxiv:2611.01623</guid><pubDate>Sun, 01 Nov 2026 00:00:00 GMT</pubDate><description>Hongyu Chen, Li Ma, Li Sheng — On every unit-volume flat complex three-torus, we construct a solution of the volume-preserving conformal Chern–Calabi flow with a finite-time Chern Type-I singularity at any prescribed point. The full spatial supremum has an exact asymptotic coefficient, and prescribed rescalings converge to a complete nonflat radial shrinking solution. The positive part of Chern scalar curvature can remain arbitrarily small throughout the flow, as can each prescribed subcritical spatial curvature norm. We determine the punctured terminal metric, its one-point completion and unique nonflat tangent cone, and the terminal energy asymptotics. We also exclude Chern Type-II under a logarithmically improved critical weak L³ bound on Chern scalar curvature, and prove a separate scale-invariant integral criterion involving first Chern–Ricci curvature. The constructed singular solutions satisfy both criteria.</description><category>Other curvature flows</category><category>Singularities</category><category>Kähler geometry</category><category>Scalar curvature</category><category>Kähler–Einstein &amp; K-stability</category></item>
<item><title>Backward Pseudolocality of G₂-Laplacian Flow</title><link>https://neckpinch.com/papers/2610.38418/</link><guid isPermaLink="false">arxiv:2610.38418</guid><pubDate>Wed, 28 Oct 2026 00:00:00 GMT</pubDate><description>Weiyong He, Longhuan Yan — In this paper, we establish a new estimate on the time-derivative of pointed Nash entropy and use it to give a new proof of backward pseudolocality for Ricci flow. The proof does not rely on Bamler&apos;s compactness theorem and structure theory concerning limits of Ricci flows. Our methods also work for other reasonable geometric flows, like the G₂-Laplacian, at a scale depending on its deviation from Ricci flow and its scalar curvature.</description><category>Ricci flow</category><category>Generalized &amp; G₂ flows</category><category>Perelman entropy</category><category>Scalar curvature</category><category>Limit spaces &amp; RCD</category></item>
<item><title>Pseudolocality of G₂-Laplacian Flow</title><link>https://neckpinch.com/papers/2610.38408/</link><guid isPermaLink="false">arxiv:2610.38408</guid><pubDate>Wed, 28 Oct 2026 00:00:00 GMT</pubDate><description>Weiyong He, Longhuan Yan — In this paper, we give a new proof of Perelman&apos;s pseudolocality theorem for Ricci flow, which does not rely on Perelman&apos;s Harnack-type inequality. The key step is an estimate relating initial local μ-entropy to pointed Nash entropy at later spacetime points. The argument also works for other reasonable geometric flows, like the G₂-Laplacian flow, at a scale depending on its deviation from Ricci flow and its scalar curvature lower bound. As a consequence, we can also prove the quantitative rigidity results concerning pointed Nash entropy due to Hein-Naber and Bamler for such geometric flows. In the appendix, we also show that the other results in Bamler&apos;s work (arXiv:2008.07093), when suitably modified, remain valid for Laplacian flow with bounded torsion. These include log-Sobolev/Poincaré inequality for conjugate heat kernel measure, heat kernel estimates, and dependence of the pointed Nash entropy on its basepoint.</description><category>Ricci flow</category><category>Generalized &amp; G₂ flows</category><category>Perelman entropy</category><category>Harnack inequalities</category><category>Heat kernel</category><category>Scalar curvature</category><category>Stability &amp; uniqueness</category></item>
<item><title>Rigidity of Constant-Scalar-Curvature Ricci Shrinkers with Totally Geodesic Focal Set</title><link>https://neckpinch.com/papers/2610.37151/</link><guid isPermaLink="false">arxiv:2610.37151</guid><pubDate>Tue, 27 Oct 2026 00:00:00 GMT</pubDate><description>Fengjiang Li, Wenqi Li, Jianyu Ou, Yuanyuan Qu, Guoqiang Wu, Detang Zhou — Let (Mⁿ,g,f) be a complete connected shrinking gradient Ricci soliton with constant scalar curvature, satisfying Ric+∇²f=1/2g. We prove that if the focal set of f is totally geodesic, then M is rigid. Equivalently, its universal cover is a product of a compact Einstein manifold and a Euclidean space.</description><category>Ricci solitons</category><category>Einstein metrics</category><category>Scalar curvature</category><category>Stability &amp; uniqueness</category></item>
<item><title>Pseudo-Calabi Flow on Toric Variety</title><link>https://neckpinch.com/papers/2610.34340/</link><guid isPermaLink="false">arxiv:2610.34340</guid><pubDate>Sun, 25 Oct 2026 00:00:00 GMT</pubDate><description>Junhao Tian, Kai Zheng — In this paper, we prove the long time existence of the pseudo-Calabi flow on a compact toric variety for any Tⁿ-invariant initial Kähler metric. If the Mabuchi functional is proper modulo automorphisms, the flow converges exponentially to a constant scalar curvature Kähler (cscK) metric. In particular, this gives a flow proof that properness of the K-energy implies the existence of a cscK metric in the toric setting.</description><category>Other curvature flows</category><category>Kähler geometry</category><category>Scalar curvature</category><category>Long-time existence &amp; convergence</category><category>Kähler–Einstein &amp; K-stability</category></item>
<item><title>Continuation and convergence for the higher dimensional conformal Chern–Calabi flow</title><link>https://neckpinch.com/papers/2610.31270/</link><guid isPermaLink="false">arxiv:2610.31270</guid><pubDate>Thu, 22 Oct 2026 00:00:00 GMT</pubDate><description>Hongyu Chen, Li Ma, Li Sheng — We study the volume-normalized gradient flow of the squared Chern scalar curvature on compact Hermitian manifolds of complex dimension n≥3. The flow extends smoothly past a finite time if the spatial supremum of Chern scalar curvature belongs to L² in time. A uniform curvature bound in the evolving L^p norm, for one fixed p&gt;n, gives global existence and smooth convergence of the whole trajectory to a constrained critical metric. On Chern scalar-flat backgrounds, small initial L^p curvature gives exponential convergence to the background. A corresponding condition on the trace-free first Chern–Ricci form gives exponential convergence on Chern–Ricci-flat Hermitian and positive Kähler–Einstein backgrounds. The smallness thresholds are independent of the initial higher derivatives. We also construct constant Chern scalar curvature backgrounds of either sign with arbitrarily small smooth perturbations whose solutions, if global, cannot converge back to the background.</description><category>Other curvature flows</category><category>Einstein metrics</category><category>Ricci-flat &amp; Calabi–Yau</category><category>Singularities</category><category>Kähler geometry</category><category>Scalar curvature</category><category>Long-time existence &amp; convergence</category><category>Kähler–Einstein &amp; K-stability</category></item>
<item><title>Type I estimates for the Kähler-Ricci flow II</title><link>https://neckpinch.com/papers/2610.22941/</link><guid isPermaLink="false">arxiv:2610.22941</guid><pubDate>Fri, 16 Oct 2026 00:00:00 GMT</pubDate><description>Wangjian Jian, Jian Song — In this paper, we establish geometric consequences of our Type I scalar curvature estimate for finite-time solutions of the Kähler-Ricci flow on compact Kähler manifolds. We prove a uniform global diameter bound and a Type I diameter bound for every fibre of finite time holomorphic contraction. These estimates yield Gromov-Hausdorff convergence to a unique compact metric space homeomorphic to the normal Kähler space determined by the limiting cohomology class. We also establish a local partial C⁰ estimate for the normalized flow and show that the tangent shrinkers are normal complex analytic varieties with log terminal singularities.</description><category>Ricci flow</category><category>Kähler–Ricci flow</category><category>Ricci solitons</category><category>Singularities</category><category>Kähler geometry</category><category>Scalar curvature</category><category>Limit spaces &amp; RCD</category><category>Analytic minimal model program</category></item>
<item><title>Gromov-Hausdorff Convergence of Constant Scalar Curvature Kähler Metrics near the Canonical Class</title><link>https://neckpinch.com/papers/2610.21934/</link><guid isPermaLink="false">arxiv:2610.21934</guid><pubDate>Thu, 15 Oct 2026 00:00:00 GMT</pubDate><description>Frederick Tsz-Ho Fong, Junbang Liu — Let X be a compact Kähler manifold with semi-ample canonical bundle. For any Kähler class [ω], Jian–Shi–Song proved that there exists a unique cscK metric in the class 2πc₁(K_X)+ε[ω] when ε∈ (0,ε₀], using the properness criterion of Chen–Cheng. We prove that the cscK metrics in 2πc₁(K_X)+ε[ω] converge, as εdownarrow0, in the Gromov–Hausdorff topology to the metric completion of the twisted Kähler-Einstein metric on the canonical model of X as conjectured by Jian–Shi–Song. Based on the technique developed in this paper, we can also give a new proof the theorem of Lee–Tosatti–Zhang on the Gromov-Hausdorff convergence of the normalized Kähler–Ricci flow on X.</description><category>Ricci flow</category><category>Kähler–Ricci flow</category><category>Einstein metrics</category><category>Kähler geometry</category><category>Scalar curvature</category><category>Limit spaces &amp; RCD</category><category>Kähler–Einstein &amp; K-stability</category><category>Analytic minimal model program</category></item>
<item><title>Finite Time Noncollapsing Kähler-Ricci Flow: Gaussian Type Heat Kernel, Gromov-Hausdorff Limits</title><link>https://neckpinch.com/papers/2610.21824/</link><guid isPermaLink="false">arxiv:2610.21824</guid><pubDate>Thu, 15 Oct 2026 00:00:00 GMT</pubDate><description>Lei Zhang, Zhenlei Zhang — In this paper, we study heat kernel estimates along the Kähler-Ricci flow with finite time noncollapsing singularities over a compact Kähler manifold. The starting point is the type-II scalar-curvature estimate, which gives the natural parabolic scale r≲ T-t near the singular time. By combining the distance distortion and space-time cut-off estimates of Bamler–Zhang with entropy, mean-value inequality, and conjugate heat-kernel estimates, we obtain two-sided Gaussian bounds and gradient bounds that are uniform on this scale. Under the global type-I scalar-curvature estimate, the same estimates hold on every scale. We then use these estimates and the monotonicity of the W₁-distance between conjugate heat flows to construct a canonical singular-time pseudo-distance. The distances dₜ (induced by ω(t)) converge uniformly to this pseudo-distance. Its metric quotient is the unique Gromov–Hausdorff limit. Finally, we apply Bamler&apos;s theory and the recent work of Hallgren–Zhang to obtain the following. Every fixed-base-point type-I blow-up admits a subsequential metric-flow limit whose time slices are singular shrinking Kähler–Ricci soliton spaces with normal complex-analytic and log-terminal structure, unique tangent cones, and a polarized Fano fibration. For moving base points, the limiting metric flow, equipped with its limiting conjugate heat flow, is a metric soliton precisely under an entropy-pinching condition.</description><category>Ricci flow</category><category>Kähler–Ricci flow</category><category>Ricci solitons</category><category>Kähler–Ricci solitons</category><category>Singularities</category><category>(Non)collapsing</category><category>Heat kernel</category><category>Curvature pinching</category><category>Kähler geometry</category><category>Scalar curvature</category></item>
<item><title>A note on the Chern-Yamabe flow on compact Hermitian manifolds with negative Gauduchon degree</title><link>https://neckpinch.com/papers/2610.15326/</link><guid isPermaLink="false">arxiv:2610.15326</guid><pubDate>Sun, 11 Oct 2026 00:00:00 GMT</pubDate><description>Weike Yu — In this note, we prove that on a compact Hermitian manifold with negative Gauduchon degree, the Chern-Yamabe flow introduced in our recent work [13] converges to the solution of prescribed Chern scalar curvature problem, provided that the candidate curvature function is nonpositive and not identically zero.</description><category>Yamabe flow</category><category>Scalar curvature</category></item>
<item><title>Rigidity of Kähler-Ricci Solitons with Constant Scalar Curvature</title><link>https://neckpinch.com/papers/2610.11935/</link><guid isPermaLink="false">arxiv:2610.11935</guid><pubDate>Thu, 08 Oct 2026 00:00:00 GMT</pubDate><description>Matheus Horácio, Wenqi Li, Jianyu Ou, Guoqiang Wu, Detang Zhou — Let (M^(2m),g,f,J) be a complete nonsteady gradient Kähler-Ricci soliton satisfying Ric+∇² f=λg, λ≠ 0. We prove that constant scalar curvature forces the soliton to be rigid. More precisely, the universal cover splits holomorphically and isometrically as N^(2k)×ℂ^(m-k), where N^(2k) is Kähler-Einstein with Ric_(g_N)=λg_N. In the shrinking case the quotient is trivial; in the normalization λ=1/2 one has R≡ k. The Kähler result rests on a Riemannian rigidity criterion. On a complete nonsteady gradient Ricci soliton, if 𝓛_∇fRic is nonnegative or nonpositive everywhere, then it vanishes and the soliton is rigid; no assumption on the scalar curvature is needed. Along the Ricci flow generated by the soliton, this means that a Ricci tensor that is monotone in time is constant in time, and that this forces rigidity. We also give a direct proof that the pinching 0≤Ric≤λg forces constant scalar curvature and radial flatness, yielding the rigidity conclusion through the Petersen-Wylie characterization. The proof combines a weighted cutoff argument with a partial Codazzi symmetry for the Ricci endomorphism.</description><category>Ricci flow</category><category>Ricci solitons</category><category>Kähler–Ricci solitons</category><category>Einstein metrics</category><category>Curvature pinching</category><category>Kähler geometry</category><category>Scalar curvature</category><category>Stability &amp; uniqueness</category><category>Kähler–Einstein &amp; K-stability</category></item>
<item><title>On Ricci solitons whose level hypersurfaces have parallel second fundamental form</title><link>https://neckpinch.com/papers/2610.11209/</link><guid isPermaLink="false">arxiv:2610.11209</guid><pubDate>Thu, 08 Oct 2026 00:00:00 GMT</pubDate><description>Matheus Andrade Ribeiro de Moura Horácio — We study gradient Ricci solitons whose potential functions have level hypersurfaces with parallel second fundamental form. We show that such a soliton is locally a multiply warped product of a one-dimensional base and Einstein fibers, with potential function depending only on the base. Thus, locally, this condition characterizes the multiply warped structure that occurs in many classical constructions of Ricci solitons. We further prove that the same local structure follows for any gradient Ricci soliton if just one regular level hypersurface has parallel second fundamental form and parallel intrinsic Ricci tensor. As an application, we prove that a complete nonsteady gradient Ricci soliton with constant scalar curvature is rigid as soon as one regular level hypersurface has this property. In particular, the conjecture of Cao holds for gradient shrinking Ricci solitons with this property. We also prove that a complete gradient shrinking Ricci soliton whose regular level hypersurfaces have parallel second fundamental form and at most one nonzero principal curvature is rigid, without any assumption on the scalar curvature.</description><category>Ricci solitons</category><category>Scalar curvature</category><category>Rotational symmetry &amp; warped products</category></item>
<item><title>L² Curvature Bounds on Ricci flows with bounded scalar curvature up to dimension 7</title><link>https://neckpinch.com/papers/2610.10575/</link><guid isPermaLink="false">arxiv:2610.10575</guid><pubDate>Mon, 05 Oct 2026 00:00:00 GMT</pubDate><description>Xianbin Huang, Wancheng Zhang — In this paper, we study Ricci flows with uniformly bounded scalar curvature. On such Ricci flows we establish uniform L² Riemannian curvature bounds and L⁴ Ricci curvature bounds up to dimension 7. These estimates improves L^(2-ε) curvature bounds established by Bamler and L² curvature bounds in dimension 4 established by Bamler and Zhang. More generally, we establish uniform L² curvature bounds on n-manifolds satisfying an integral L^p Ricci curvature bound for p&gt; n/2, a uniform volume lower bound, and a strong ε-regularity assumption. This result extends the celebrated L² curvature estimates of Jiang and Naber, which were established under pointwise two-sided Ricci curvature bounds. To overcome the lack of pointwise control, we develop an L^p adaptation of the neck decomposition theorem and establish a superconvexity estimate for the curvature on neck regions. Furthermore, we demonstrate that our structural assumptions are dynamically natural on Ricci flows with bounded scalar curvature. As an application, by combining our estimate with the a priori L^(4-ε) curvature radius bound of Ricci flow established by Bamler, we obtain uniform L² curvature bounds on Ricci flows with bounded scalar curvature of dimension n ≤ 7.</description><category>Ricci flow</category><category>4-manifolds</category><category>Scalar curvature</category></item>
<item><title>Scalar curvature bounds and tangent cones for Kähler–Ricci shrinkers</title><link>https://neckpinch.com/papers/2610.05643/</link><guid isPermaLink="false">arxiv:2610.05643</guid><pubDate>Mon, 05 Oct 2026 00:00:00 GMT</pubDate><description>Yu Li, Junsheng Zhang — We prove a uniform scalar curvature bound, depending only on the dimension, for Kähler–Ricci shrinkers. We also prove that every noncompact Kähler–Ricci shrinker has a unique tangent cone at infinity, naturally homeomorphic to the base of its polarized Fano fibration. For shrinkers with maximal volume growth, this cone is isometric to the metric completion of the regular part equipped with the intrinsic distance induced by the limiting Kähler metric.</description><category>Ricci solitons</category><category>Kähler geometry</category><category>Scalar curvature</category><category>Boundaries &amp; non-compact</category><category>Analytic minimal model program</category></item>
<item><title>Generalized scalar curvature and Ricci flow on compact Lie groups</title><link>https://neckpinch.com/papers/2610.03795/</link><guid isPermaLink="false">arxiv:2610.03795</guid><pubDate>Thu, 01 Oct 2026 00:00:00 GMT</pubDate><description>Zhiqi Chen, Jianhua Yu, Huibin Chen, Junna Ni — Let G be a compact connected semisimple Lie group, let Q be a bi-invariant metric and let ρ be its Cartan three-form. We prove that every left-invariant generalized Ricci flow with [H₀]=[ρ] exists for all positive time and converges smoothly to a Bismut-Ricci-flat pair without rescaling or pullback. The standard pair uniquely maximizes generalized scalar curvature in its torsion class, and every left-invariant Bismut-Ricci-flat pair on a compact simple group is standard, answering questions of Fusi, Lafuente and Stanfield and of Lauret and Will. On the product of two copies of a compact simple group, nonstandard stationary pairs in the Cartan class are known; we construct nonstationary flows with the exact initial form [H₀]=[ρ] and nonstandard limits, disproving the general semisimple case of the convergence conjecture of Garcia-Fernandez and Streets. The proofs use a proper nonincreasing energy and a decomposition of Killing fields that parametrizes the stationary pairs by nilpotent Lie algebra endomorphisms.</description><category>Ricci flow</category><category>Generalized &amp; G₂ flows</category><category>Ricci-flat &amp; Calabi–Yau</category><category>Scalar curvature</category><category>Homogeneous spaces</category><category>Long-time existence &amp; convergence</category></item>
<item><title>Type I estimates for the Kahler-Ricci flow I</title><link>https://neckpinch.com/papers/2609.39620/</link><guid isPermaLink="false">arxiv:2609.39620</guid><pubDate>Wed, 30 Sep 2026 00:00:00 GMT</pubDate><description>Wangjian Jian, Jian Song — We establish the Type I estimate for the scalar curvature of the Kahler-Ricci flow on compact Kahler manifolds, for arbitrary smooth initial metrics, whenever the flow develops finite time singularities. This estimate is a building block for the analytic minimal model program with Ricci flow.</description><category>Ricci flow</category><category>Kähler–Ricci flow</category><category>Singularities</category><category>Kähler geometry</category><category>Scalar curvature</category><category>Analytic minimal model program</category></item>
<item><title>Kähler–Ricci Shrinkers with Constant Scalar Curvature Are Rigid</title><link>https://neckpinch.com/papers/2609.36418/</link><guid isPermaLink="false">arxiv:2609.36418</guid><pubDate>Tue, 29 Sep 2026 00:00:00 GMT</pubDate><description>Wenqi Li, Jianyu Ou, Guoqiang Wu, Detang Zhou — Let (M^(2m),g,f,J) be a complete gradient Kähler–Ricci shrinker satisfying Ric+∇² f=1/2 g. We prove that if the scalar curvature is constant, then the soliton is rigid. More precisely, there exists an integer k∈\0,…,m\ such that R≡ k and (M^(2m),g,J)≅ bigl(N^(2k)×ℂ^(m-k), g_N+g_Euc,J_N⊕ J₀bigr), where (N^(2k),g_N,J_N) is Kähler–Einstein and Ric_(g_N)=1/2 g_N. As part of the proof, we establish a Riemannian rigidity criterion: for a complete nonsteady gradient Ricci soliton with constant scalar curvature, the condition 𝓛_∇fRic=0 implies radial flatness and hence rigidity.</description><category>Ricci solitons</category><category>Einstein metrics</category><category>Kähler geometry</category><category>Scalar curvature</category><category>Stability &amp; uniqueness</category><category>Kähler–Einstein &amp; K-stability</category></item>
<item><title>Rigidity of nonsteady gradient Kähler-Ricci solitons with constant scalar curvature</title><link>https://neckpinch.com/papers/2609.29359/</link><guid isPermaLink="false">arxiv:2609.29359</guid><pubDate>Thu, 24 Sep 2026 00:00:00 GMT</pubDate><description>Matheus Andrade Ribeiro de Moura Horácio — We prove that every complete nonsteady gradient Kähler-Ricci soliton with constant scalar curvature is rigid. This establishes Cao&apos;s rigidity conjecture for Kähler-Ricci solitons in arbitrary dimension and gives the corresponding result for expanding solitons, without additional curvature assumptions. The proof uses a rigidity criterion for gradient Ricci solitons with constant scalar curvature, expressed by the vanishing of the Lie derivative of the Ricci tensor along the soliton vector field. In the Kähler case, this vanishing follows from constant scalar curvature, the closedness of the Ricci form, and the classical real holomorphicity of the soliton vector field.</description><category>Ricci solitons</category><category>Kähler–Ricci solitons</category><category>Kähler geometry</category><category>Scalar curvature</category><category>Stability &amp; uniqueness</category></item>
<item><title>A continuous Positive Mass Theorem for perturbations of Euclidean space</title><link>https://neckpinch.com/papers/2609.25550/</link><guid isPermaLink="false">arxiv:2609.25550</guid><pubDate>Tue, 22 Sep 2026 00:00:00 GMT</pubDate><description>Paula Burkhardt-Guim — We prove a Positive Mass Theorem for C⁰-asymptotically flat Riemannian metrics with nonnegative scalar curvature in a weak sense that are sufficiently uniformly close to Euclidean space. More precisely, we show that a C⁰-asymptotically flat Riemannian metric that is a C⁰ perturbation of Euclidean space with nonnegative scalar curvature in the sense of Ricci flow has nonnegative mass, where the mass is given by a C⁰ analog of the classical ADM mass previously introduced by the author.</description><category>Ricci flow</category><category>Scalar curvature</category><category>Boundaries &amp; non-compact</category><category>Physics</category></item>
<item><title>Finite-Time Singularities of the Kähler–Ricci Flow on Fano Bundles II</title><link>https://neckpinch.com/papers/2609.20513/</link><guid isPermaLink="false">arxiv:2609.20513</guid><pubDate>Thu, 17 Sep 2026 00:00:00 GMT</pubDate><description>Wangjian Jian, Jian Song — The analytic minimal model program proposed in seeks to describe the birational transitions and fibre collapsing of the Kähler–Ricci flow through the geometry of its singularities. A fundamental conjecture of predicts Type I bounds for the scalar curvature and diameter of every fibre contratced by the limiting cohomological class at the finite singular time. This paper is a continuation of that establishes the Type I conjecture for collapsing solutions on Fano bundles with arbitrary smooth Fano fibres. If the fibre admits a smooth Kähler-Einstein metric, the Type I bound holds for the full curvature tensor.</description><category>Ricci flow</category><category>Kähler–Ricci flow</category><category>Einstein metrics</category><category>Singularities</category><category>(Non)collapsing</category><category>Kähler geometry</category><category>Scalar curvature</category><category>Kähler–Einstein &amp; K-stability</category><category>Analytic minimal model program</category></item>
<item><title>Total scalar curvature under a curvature operator lower bound</title><link>https://neckpinch.com/papers/2609.19851/</link><guid isPermaLink="false">arxiv:2609.19851</guid><pubDate>Thu, 17 Sep 2026 00:00:00 GMT</pubDate><description>Jian Ge, Chuanhuan Li, Ronggang Li — Let (Mⁿ, g) be a complete, simply connected Riemannian manifold without boundary, of dimension n≥3, with curvature operator at least that of the unit sphere. We prove that ∫_M rm scal(x) d rm Volₓ≤ n(n-1)ωₙ, where ωₙ is the volume of the unit n-sphere. Equality holds if and only if (M,g) is isometric to the unit round sphere. In fact, we obtain a stronger bound containing rm Vol(M, g). In even dimensions, the proof follows from the Chern-Gauss-Bonnet formula. In odd dimensions, we apply the corresponding boundary formula to Deruelle&apos;s Ricci expander filling.</description><category>Ricci solitons</category><category>Scalar curvature</category></item>
<item><title>Deforming area-preserving maps between surfaces by mean curvature flow coupled with Ricci flow</title><link>https://neckpinch.com/papers/2609.19724/</link><guid isPermaLink="false">arxiv:2609.19724</guid><pubDate>Thu, 17 Sep 2026 00:00:00 GMT</pubDate><description>Ping-Hung Lee — We study a natural way to deform area-preserving maps between compact Riemann surfaces. Specifically, we evolve the metrics on the two Riemann surfaces by the normalized Ricci flow and the graph of the area-preserving map by the mean curvature flow. We prove that the flow exists for all time, remains the graph of an area-preserving map, and converges smoothly and exponentially to a minimal Lagrangian graph with respect to the product of the limiting metrics. This generalizes earlier results of Wang and Smoczyk, in which the Riemann surfaces have constant scalar curvature.</description><category>Ricci flow</category><category>Mean curvature flow</category><category>Lagrangian mean curvature flow</category><category>Surfaces</category><category>Scalar curvature</category><category>Long-time existence &amp; convergence</category><category>Discrete &amp; graph Ricci</category></item>
<item><title>K-contact manifolds admitting some geometric solitons with Semi-Symmetric Non-Metric Connection</title><link>https://neckpinch.com/papers/2609.15147/</link><guid isPermaLink="false">arxiv:2609.15147</guid><pubDate>Mon, 14 Sep 2026 00:00:00 GMT</pubDate><description>Bidhan Mondal, Nirabhra Basu, Arindam Bhattacharyya — In this paper, we introduce some type vector fields with respect to a semi-symmetric non-metric (SSNM) connection. We investigate several geometric properties of a K-contact manifold equipped with an SSNM connection and provide a concrete example to justify the relation between the scalar curvature of the SSNM connection and Levi-Civita connection that we have obtained in this paper. Furthermore, we have found the nature of Riemann solitons, conformal Ricci solitons and conformal η-Ricci-Yamabe solitons on K-contact manifolds admitting a SSNM connection.\\ Finally, we determine the necessary and sufficient conditions for such a manifold to be Tildeτ-semi-symmetric, quasi-conformal-semi-symmetric and pseudo-projective-semi-symmetric.</description><category>Ricci solitons</category><category>Almost &amp; η-Ricci solitons</category><category>Scalar curvature</category><category>Sasakian &amp; contact geometry</category></item>
<item><title>Volume comparison for 3-manifolds with 2-Ricci curvature lower bound and Ricci flow</title><link>https://neckpinch.com/papers/2609.13938/</link><guid isPermaLink="false">arxiv:2609.13938</guid><pubDate>Sat, 12 Sep 2026 00:00:00 GMT</pubDate><description>Shaochuang Huang, Zhuo Peng — In this note, we study volume comparison for 3-manifolds with 2-Ricci curvature lower bound. We establish monotonicity and rigidity for geodesic sphere area and ball volume, and derive the pointed Gromov-Hausdorff precompactness under a uniform lower bound on the conjugate radius for 3-manifolds with 2-Ricci curvature lower bound. We also discuss the almost preservation of 2-Ricci curvature lower bound and the local non-collapsing propagation along Ricci flow. Finally, we point out a topological rigidity result on nonnegative scalar curvature.</description><category>Ricci flow</category><category>(Non)collapsing</category><category>3-manifolds</category><category>Scalar curvature</category><category>Limit spaces &amp; RCD</category><category>Stability &amp; uniqueness</category></item>
<item><title>Some uniform estimates for Kähler–Ricci Shrinkers</title><link>https://neckpinch.com/papers/2608.30779/</link><guid isPermaLink="false">arxiv:2608.30779</guid><pubDate>Mon, 31 Aug 2026 00:00:00 GMT</pubDate><description>Junsheng Zhang — In this paper, we establish several uniform estimates for Kähler–Ricci shrinkers without imposing any curvature assumptions. In particular, we prove: 1. a uniform lower bound for the entropy; 2. a uniform lower bound for the asymptotic volume ratio of Kähler–shrinkers with maximal volume growth; 3. a uniform lower bound for the scalar curvature on balls centered at a minimum point of the soliton potential for non-Gaussian shrinkers.</description><category>Ricci solitons</category><category>Kähler geometry</category><category>Scalar curvature</category></item>
<item><title>Homogeneous Generalized Ricci flows II</title><link>https://neckpinch.com/papers/2608.25619/</link><guid isPermaLink="false">arxiv:2608.25619</guid><pubDate>Wed, 26 Aug 2026 00:00:00 GMT</pubDate><description>Elia Fusi, Ramiro A. Lafuente, James Stanfield — We relate the generalized Ricci curvature of left-invariant generalized metrics on a Lie group with the Ricci curvature of certain metric Lie algebras. As an application, we prove subconvergence of rescaled generalized Ricci flows to expanding generalized Ricci solitons on simply connected Lie groups with positive semi-definite Killing form. Under the same hypotheses, subconvergence of pluriclosed flows to expanding pluriclosed solitons is also shown. We further prove that left-invariant Bismut-Ricci flat metrics arise as critical points for the generalized scalar curvature functional on unimodular Lie groups. In view of this, we establish dynamical stability for the generalized Ricci flow of so-called standard bi-invariant, Bismut-flat metrics on compact, simply connected, semisimple Lie groups and construct examples of dynamically unstable Bismut-flat metrics which are non-standard.</description><category>Ricci flow</category><category>Generalized &amp; G₂ flows</category><category>Ricci solitons</category><category>Ricci-flat &amp; Calabi–Yau</category><category>Scalar curvature</category><category>Homogeneous spaces</category><category>Stability &amp; uniqueness</category></item>
<item><title>Rigidity of shrinking gradient ricci soliton with constant scalar curvature</title><link>https://neckpinch.com/papers/2608.20040/</link><guid isPermaLink="false">arxiv:2608.20040</guid><pubDate>Thu, 20 Aug 2026 00:00:00 GMT</pubDate><description>Fengjiang Li, Yuanyuan Qu, Guoqiang Wu — Let (Mⁿ, g, f) be a complete shrinking gradient Ricci soliton with constant scalar curvature. Under the assumptions that (i) Ric ≥ frac∇_∇fRicf on M∖ D, where D is a compact set over M; (ii) (Mⁿ, g, f) smoothly converges to ℝ² × Sⁿ⁻², we conclude that (Mⁿ, g, f) is isometric to ℝ² × Sⁿ⁻². Notably, condition (i) is weaker than the radial flatness condition in.</description><category>Ricci solitons</category><category>Scalar curvature</category><category>Stability &amp; uniqueness</category></item>
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