{"title":"Quasi‐invariance of Gaussian measures for the 3d$3d$ energy critical nonlinear Schrödinger equation","authors":"Chenmin Sun, Nikolay Tzvetkov","doi":"10.1002/cpa.70001","DOIUrl":"https://doi.org/10.1002/cpa.70001","url":null,"abstract":"We consider the energy critical nonlinear Schrödinger equation with data distributed according to the Gaussian measure with covariance operator , where is the Laplace operator and is sufficiently large. We prove that the flow sends full measure sets to full measure sets. We also discuss some simple applications. This extends a previous result by Planchon‐Visciglia and the second author from to higher dimensions.","PeriodicalId":10601,"journal":{"name":"Communications on Pure and Applied Mathematics","volume":"630 1","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144500756","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Bogomolov–Gieseker inequality for log terminal Kähler threefolds","authors":"Henri Guenancia, Mihai Păun","doi":"10.1002/cpa.70000","DOIUrl":"https://doi.org/10.1002/cpa.70000","url":null,"abstract":"In this article we prove the orbifold version of the Bogomolov–Gieseker inequality for stable ‐sheaves on log terminal Kähler threefolds.","PeriodicalId":10601,"journal":{"name":"Communications on Pure and Applied Mathematics","volume":"16 1","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144370695","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Free energy expansions of a conditional GinUE and large deviations of the smallest eigenvalue of the LUE","authors":"Sung‐Soo Byun, Seong‐Mi Seo, Meng Yang","doi":"10.1002/cpa.70005","DOIUrl":"https://doi.org/10.1002/cpa.70005","url":null,"abstract":"We consider a planar Coulomb gas ensemble of size with the inverse temperature and external potential , where and . Equivalently, this model can be realised as eigenvalues of the complex Ginibre matrix of size conditioned to have deterministic eigenvalue with multiplicity . Depending on the values of and , the droplet reveals a phase transition: it is doubly connected in the post‐critical regime and simply connected in the pre‐critical regime. In both regimes, we derive precise large‐ expansions of the free energy up to the term, providing a non‐radially symmetric example that confirms the Zabrodin–Wiegmann conjecture made for general planar Coulomb gas ensembles. As a consequence, our results provide asymptotic behaviour of moments of the characteristic polynomial of the complex Ginibre matrix, where the powers are of order . Furthermore, by combining with a duality formula, we obtain precise large deviation probabilities of the smallest eigenvalue of the Laguerre unitary ensemble. A key ingredient for the proof lies in the fine asymptotic behaviour of a planar orthogonal polynomial, extending a result of Betola et al. This result holds its own interest and is based on a refined Riemann–Hilbert analysis using the partial Schlesinger transform.","PeriodicalId":10601,"journal":{"name":"Communications on Pure and Applied Mathematics","volume":"147 1","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144370462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The Brownian loop measure on Riemann surfaces and applications to length spectra","authors":"Yilin Wang, Yuhao Xue","doi":"10.1002/cpa.70003","DOIUrl":"https://doi.org/10.1002/cpa.70003","url":null,"abstract":"We prove a simple identity relating the length spectrum of a Riemann surface to that of the same surface with an arbitrary number of additional cusps. Our proof uses the Brownian loop measure introduced by Lawler and Werner. In particular, we express the total mass of Brownian loops in a fixed free homotopy class on any Riemann surface in terms of the length of the geodesic representative for the complete constant curvature metric. This expression also allows us to write the electrical thickness of a compact set in separating 0 and , or the Velling–Kirillov Kähler potential, in terms of the Brownian loop measure and the zeta‐regularized determinant of Laplacian as a renormalization of the Brownian loop measure with respect to the length spectrum.","PeriodicalId":10601,"journal":{"name":"Communications on Pure and Applied Mathematics","volume":"25 1","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144334961","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Raphaël Barboni, Gabriel Peyré, François‐Xavier Vialard
{"title":"Understanding the training of infinitely deep and wide ResNets with conditional optimal transport","authors":"Raphaël Barboni, Gabriel Peyré, François‐Xavier Vialard","doi":"10.1002/cpa.70004","DOIUrl":"https://doi.org/10.1002/cpa.70004","url":null,"abstract":"We study the convergence of gradient flow for the training of deep neural networks. While residual neural networks (ResNet) are a popular example of very deep architectures, their training constitutes a challenging optimization problem, notably due to the non‐convexity and the non‐coercivity of the objective. Yet, in applications, such tasks are successfully solved by simple optimization algorithms such as gradient descent. To better understand this phenomenon, we focus here on a “mean‐field” model of an infinitely deep and arbitrarily wide ResNet, parameterized by probability measures on the product set of layers and parameters, and with constant marginal on the set of layers. Indeed, in the case of shallow neural networks, mean field models have been proven to benefit from simplified loss landscapes and good theoretical guarantees when trained with gradient flow w.r.t. the Wasserstein metric on the set of probability measures. Motivated by this approach, we propose to train our model with gradient flow w.r.t. the conditional optimal transport (COT) distance: a restriction of the classical Wasserstein distance which enforces our marginal condition. Relying on the theory of gradient flows in metric spaces, we first show the well‐posedness of the gradient flow equation and its consistency with the training of ResNets at finite width. Performing a local Polyak–Łojasiewicz analysis, we then show convergence of the gradient flow for well‐chosen initializations: if the number of features is finite but sufficiently large and the risk is sufficiently small at initialization, the gradient flow converges to a global minimizer. This is the first result of this type for infinitely deep and arbitrarily wide ResNets. In addition, this work is an opportunity to study in more detail the COT metric, particularly its dynamic formulation. Some of our results in this direction might be interesting on their own.","PeriodicalId":10601,"journal":{"name":"Communications on Pure and Applied Mathematics","volume":"29 1","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144334962","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Boundary conditions and universal finite‐size scaling for the hierarchical |φ|4$|varphi |^4$ model in dimensions 4 and higher","authors":"Emmanuel Michta, Jiwoon Park, Gordon Slade","doi":"10.1002/cpa.22256","DOIUrl":"https://doi.org/10.1002/cpa.22256","url":null,"abstract":"We analyse and clarify the finite‐size scaling of the weakly‐coupled hierarchical ‐component model for all integers in all dimensions , for both free and periodic boundary conditions. For , we prove that for a volume of size with periodic boundary conditions the infinite‐volume critical point is an effective finite‐volume critical point, whereas for free boundary conditions the effective critical point is shifted smaller by an amount of order . For both boundary conditions, the average field has the same non‐Gaussian limit within a critical window of width around the effective critical point, and in that window we compute the universal scaling profile for the susceptibility. In contrast, and again for both boundary conditions, the average field has a massive Gaussian limit when above the effective critical point by an amount . In particular, at the infinite‐volume critical point the susceptibility scales as for periodic boundary conditions and as for free boundary conditions. We identify a mass generation mechanism for free boundary conditions that is responsible for this distinction and which we believe has wider validity, in particular to Euclidean (non‐hierarchical) models on in dimensions . For we prove a similar picture with logarithmic corrections. Our analysis is based on the rigorous renormalisation group method of Bauerschmidt, Brydges and Slade, which we improve and extend.","PeriodicalId":10601,"journal":{"name":"Communications on Pure and Applied Mathematics","volume":"88 1","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143889831","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Naomi D. Feldheim, Ohad N. Feldheim, Sumit Mukherjee
{"title":"Persistence and ball exponents for Gaussian stationary processes","authors":"Naomi D. Feldheim, Ohad N. Feldheim, Sumit Mukherjee","doi":"10.1002/cpa.22255","DOIUrl":"https://doi.org/10.1002/cpa.22255","url":null,"abstract":"Consider a real Gaussian stationary process , indexed on either or and admitting a spectral measure . We study , the persistence exponent of . We show that, if has a positive density at the origin, then the persistence exponent exists; moreover, if has an absolutely continuous component, then if and only if this spectral density at the origin is finite. We further establish continuity of in , in (under a suitable metric) and, if is compactly supported, also in dense sampling. Analogous continuity properties are shown for , the ball exponent of , and it is shown to be positive if and only if has an absolutely continuous component.","PeriodicalId":10601,"journal":{"name":"Communications on Pure and Applied Mathematics","volume":"222 1","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143889830","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Boundary statistics for the six‐vertex model with DWBC","authors":"Vadim Gorin, Karl Liechty","doi":"10.1002/cpa.22254","DOIUrl":"https://doi.org/10.1002/cpa.22254","url":null,"abstract":"We study the behavior of configurations in the symmetric six‐vertex model with weights in the square with Domain Wall Boundary Conditions as . We prove that when , configurations near the boundary have fluctuations of order and are asymptotically described by the GUE‐corners process of random matrix theory. On the other hand, when , the fluctuations are of finite order and configurations are asymptotically described by the stochastic six‐vertex model in a quadrant. In the special case (which implies ), the limit is expressed as the ‐exchangeable random permutation of infinitely many letters, distributed according to the infinite Mallows measure.","PeriodicalId":10601,"journal":{"name":"Communications on Pure and Applied Mathematics","volume":"74 1","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143872730","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"On classification of global dynamics for energy‐critical equivariant harmonic map heat flows and radial nonlinear heat equation","authors":"Kihyun Kim, Frank Merle","doi":"10.1002/cpa.22253","DOIUrl":"https://doi.org/10.1002/cpa.22253","url":null,"abstract":"We consider the global dynamics of finite energy solutions to energy‐critical equivariant harmonic map heat flow (HMHF) and radial nonlinear heat equation (NLH). It is known that any finite energy equivariant solutions to (HMHF) decompose into finitely many harmonic maps (bubbles) separated by scales and a body map, as approaching to the maximal time of existence. Our main result for (HMHF) gives a complete classification of their dynamics for equivariance indices ; (i) they exist globally in time, (ii) the number of bubbles and signs are determined by the energy class of the initial data, and (iii) the scales of bubbles are asymptotically given by a universal sequence of rates up to scaling symmetry. In parallel, we also obtain a complete classification of ‐bounded radial solutions to (NLH) in dimensions , building upon soliton resolution for such solutions. To our knowledge, this provides the first rigorous classification of bubble tree dynamics within symmetry. We introduce a new approach based on the energy method that does not rely on maximum principle. The key ingredient of the proof is a monotonicity estimate near any bubble tree configurations, which in turn requires a delicate construction of modified multi‐bubble profiles also.","PeriodicalId":10601,"journal":{"name":"Communications on Pure and Applied Mathematics","volume":"9 1","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143847057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Maximum of the characteristic polynomial of i.i.d. matrices","authors":"Giorgio Cipolloni, Benjamin Landon","doi":"10.1002/cpa.22250","DOIUrl":"https://doi.org/10.1002/cpa.22250","url":null,"abstract":"We compute the leading order asymptotic of the maximum of the characteristic polynomial for i.i.d. matrices with real or complex entries. In particular, this result is new even for real Ginibre matrices, which was left as an open problem in Lambert et al. Electron. J. Probab. 29 (2024); the complex Ginibre case was covered in Lambert, Comm. Math Phys. 378 (2020). These are the first universality results for the non‐Hermitian analog of the first order term of the Fyodorov–Hiary–Keating conjecture. Our methods are based on constructing a coupling to the branching random walk (BRW) via Dyson Brownian motion. In particular, we find a new connection between real i.i.d. matrices and inhomogeneous BRW.","PeriodicalId":10601,"journal":{"name":"Communications on Pure and Applied Mathematics","volume":"14 1","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143805899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}