{"title":"Marginally outer trapped surface with capillary boundary and rigidity of initial data sets","authors":"Sanghun Lee","doi":"10.1007/s11005-026-02176-3","DOIUrl":"10.1007/s11005-026-02176-3","url":null,"abstract":"<div><p>In this paper, we establish a series of rigidity results for initial data sets with boundary in the presence of marginally outer trapped surfaces (MOTSs) satisfying a capillary boundary condition. Our first result establishes area estimates for stable MOTS with capillary boundary. Building on this, we prove a rigidity theorem for three-dimensional initial data sets with boundary. We further extend the rigidity to higher dimensions by employing the Yamabe constant associated to the MOTS. Finally, under a low-index assumption, we obtain additional topological restrictions on MOTS with capillary boundary.</p></div>","PeriodicalId":685,"journal":{"name":"Letters in Mathematical Physics","volume":"116 6","pages":""},"PeriodicalIF":1.6,"publicationDate":"2026-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149189622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"BV pushforward of Palatini–Cartan gravity","authors":"Giovanni Canepa, Alberto S. Cattaneo","doi":"10.1007/s11005-026-02149-6","DOIUrl":"10.1007/s11005-026-02149-6","url":null,"abstract":"<div><p>The goal of this note is to show that the standard BV formulation of gravity in the Palatini–Cartan formalism is equivalent, using a BV pushforward, to an AKSZ-like version compatible with BFV data on the boundary.\u0000</p></div>","PeriodicalId":685,"journal":{"name":"Letters in Mathematical Physics","volume":"116 6","pages":""},"PeriodicalIF":1.6,"publicationDate":"2026-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11005-026-02149-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149189590","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Max A. Alekseyev, Winfried Bruns, Jingcheng Dong, Sebastien Palcoux
{"title":"Classifying integral Grothendieck rings up to rank 5 and beyond","authors":"Max A. Alekseyev, Winfried Bruns, Jingcheng Dong, Sebastien Palcoux","doi":"10.1007/s11005-026-02164-7","DOIUrl":"10.1007/s11005-026-02164-7","url":null,"abstract":"<div><p>In this paper, we define a Grothendieck ring as a fusion ring categorifiable into a fusion category over the complex field. An integral fusion ring is called Drinfeld if all its formal codegrees are integers dividing the global Frobenius–Perron dimension. Every integral Grothendieck ring is necessarily Drinfeld. Using the fact that the formal codegrees of integral Drinfeld rings form an Egyptian fraction summing to 1, we derive a finite list of candidate global FPdims for small ranks, covering all that occur. Using Normaliz (an open-source software for computing algebraic polyhedra), we classify all integral fusion rings with these candidate FPdims, retaining only those admitting a Drinfeld structure. To exclude Drinfeld rings that are not Grothendieck rings, we analyze induction matrices to the Drinfeld center, classified via our new feature on Normaliz. Further exclusions and constructions involve group-theoretical fusion categories and Schur multipliers. Our main result is a complete classification of integral Grothendieck rings up to rank 5, extended to rank 7 in odd-dimensional and noncommutative cases using Frobenius–Schur indicators and Galois theory. Moreover, we show that any noncommutative, odd-dimensional, integral Grothendieck ring of rank at most 22 is pointed of rank 21. We also classify all integral 1-Frobenius Drinfeld rings of rank 6, identify the first known non-Isaacs integral fusion category (which turns out to be group-theoretical), and classify integral noncommutative Drinfeld rings of rank 8 and integral 1-Frobenius MNSD Drinfeld rings of rank 9. Finally, we determine the smallest rank simple exotic integral fusion rings: rank 4 in general, rank 6 in the Drinfeld case, and rank 7 in the 1-Frobenius Drinfeld case.</p></div>","PeriodicalId":685,"journal":{"name":"Letters in Mathematical Physics","volume":"116 6","pages":""},"PeriodicalIF":1.6,"publicationDate":"2026-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149176708","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Philippe Bonneau, Véronique Chloup, Angela Gammella-Mathieu, Tilmann Wurzbacher
{"title":"Actions of Lie 2-algebras and comomentum maps","authors":"Philippe Bonneau, Véronique Chloup, Angela Gammella-Mathieu, Tilmann Wurzbacher","doi":"10.1007/s11005-026-02154-9","DOIUrl":"10.1007/s11005-026-02154-9","url":null,"abstract":"<div><p>In this article we first introduce the notion of a 2-action of a Lie 2-algebra on an arbitrary manifold <i>M</i>. C.L. Rogers associates in [10] a <span>(L_{infty })</span>-algebra <span>(mathsf {L^{infty }(M,omega )})</span> to a <i>n</i>-plectic manifold <span>((M,omega ))</span>, as a higher analogue of the Poisson algebra of observables associated to a symplectic manifold. This <span>(L_{infty })</span>-algebra reduces to a Lie 2-algebra <span>(mathsf {L^2(M,omega )})</span> when <span>((M,omega ))</span> is 2-plectic. Following ideas of N.L. Delgado (cf. [4]), we introduce the Lie 2-algebra <span>(mathsf {D^2(M,omega )})</span>, which generalises the Lie 2-algebra <span>(textsf{L}^2(M,omega ))</span>, and its extension <span>(mathsf {widetilde{D^2(M,omega )}})</span> containing Hamiltonian pairs. Given a 2-plectic manifold <span>((M,omega ))</span> and a Lie 2-algebra <span>(mathfrak {g}_{-1}oplus mathfrak {g}_{0})</span> acting on <i>M</i> we define a comomentum map as a lift of the action, i.e., as a Lie 2-algebra morphism from <span>(mathfrak {g}_{-1}oplus mathfrak {g}_{0})</span> to the Lie 2-algebra <span>(mathsf {widetilde{D^2(M,omega )}})</span>. In an appendix, we discuss very explicitly numerous examples, classified according to their algebraic properties.</p></div>","PeriodicalId":685,"journal":{"name":"Letters in Mathematical Physics","volume":"116 6","pages":""},"PeriodicalIF":1.6,"publicationDate":"2026-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149176720","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Infinite-dimensional representations of (U_q(mathfrak {sl}_2)) and the shadow world: quantum 6j-symbols for Verma modules","authors":"Dmitry Solovyev","doi":"10.1007/s11005-026-02133-0","DOIUrl":"10.1007/s11005-026-02133-0","url":null,"abstract":"<div><p>This paper initiates the study of invariants of links associated to infinite-dimensional representations of <span>(U_q(mathfrak {sl}_2))</span> using graphical representation for quantum 6<i>j</i>-symbols, the shadow world. We obtain formulae for <i>q</i>3<i>j</i>-symbols and <i>q</i>6<i>j</i>-symbols for Verma modules and study their properties. This hints at the structure of a possible target category for Reshetikhin-Turaev functor for such an invariant.\u0000</p></div>","PeriodicalId":685,"journal":{"name":"Letters in Mathematical Physics","volume":"116 6","pages":""},"PeriodicalIF":1.6,"publicationDate":"2026-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149176615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A (3times 3) linear q-difference system with (E_8^{(1)})-symmetry","authors":"Takahiko Nobukawa","doi":"10.1007/s11005-026-02161-w","DOIUrl":"10.1007/s11005-026-02161-w","url":null,"abstract":"<div><p>We present a linear <i>q</i>-difference equation of rank 3, which admits the affine Weyl group symmetry of type <span>(E_8^{(1)})</span>. This equation has essentially 8 parameters and 2 accessory parameters. We characterize this equation by the spectral type of <i>q</i>-difference system which is introduced by Sakai–Yamaguchi. We further compare this equation with Moriyama–Yamada’s quantum curve which has <span>(W(E_8^{(1)}))</span>-symmetry. We show that our equation can be regarded as an extension of Moriyama–Yamada’s curve. We introduce the point configuration of a higher-order scalar <i>q</i>-difference equation to characterize our equation and clarify the corresponding between our equation and the curve. The symmetry of our equation is provided by the <i>q</i>-middle convolution, defined by Sakai–Yamaguchi and reformulated by Arai–Takemura. In this paper, we provide a reconstruction of the <i>q</i>-middle convolution via a <i>q</i>-Okubo-type equation. This construction is a natural <i>q</i>-analog of the middle convolution of Fuchsian differential equation. Several properties for our <i>q</i>-middle convolution are also discussed.\u0000</p></div>","PeriodicalId":685,"journal":{"name":"Letters in Mathematical Physics","volume":"116 5","pages":""},"PeriodicalIF":1.6,"publicationDate":"2026-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11005-026-02161-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149189098","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The continuum limit analysis of causal fermion systems for curved spacetimes","authors":"Felix Finster, Patrick Fischer","doi":"10.1007/s11005-026-02168-3","DOIUrl":"10.1007/s11005-026-02168-3","url":null,"abstract":"<div><p>We construct the causal fermion system for globally hyperbolic spacetimes starting in the framework of algebraic quantum field theory. The fermionic projector is identified with the one-particle density operator of a quasi-free Hadamard state. The ultraviolet regularization is built into the fermionic projector via a chart-independent <span>(ivarepsilon )</span>-regularization scheme. The continuum limit analysis is developed in globally hyperbolic spacetimes. It is shown that the Euler–Lagrange equations of the causal action principle are satisfied in this setup if and only if the coupled Einstein–Dirac equations hold.\u0000</p></div>","PeriodicalId":685,"journal":{"name":"Letters in Mathematical Physics","volume":"116 5","pages":""},"PeriodicalIF":1.6,"publicationDate":"2026-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11005-026-02168-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149132639","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"On the partial semi-classical Weyl’s law","authors":"Younghun Hong, Sangdon Jin","doi":"10.1007/s11005-026-02173-6","DOIUrl":"10.1007/s11005-026-02173-6","url":null,"abstract":"<div><p>In this article, we establish the partial semi-classical Weyl’s laws for a bounded domain model and a harmonic trap model, describing the quantum subband structures for two-dimensional electron gases (2DEGs). As a simple application, we derive the lowest free energy states for the subband models describing non-interacting 2DEGs.\u0000</p></div>","PeriodicalId":685,"journal":{"name":"Letters in Mathematical Physics","volume":"116 5","pages":""},"PeriodicalIF":1.6,"publicationDate":"2026-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149132640","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"On singular solitons of the KP equation and the Go-diagrams","authors":"Shilong Huang","doi":"10.1007/s11005-026-02172-7","DOIUrl":"10.1007/s11005-026-02172-7","url":null,"abstract":"<div><p>It has been proven that real and regular soliton solutions of the KP equation are classified in terms of the totally nonnegative Grassmannian. It is well known that vertex operators can be used to construct soliton solutions. In this paper, we consider several regular soliton solutions and study their combinations through products of vertex operators. In general, the resulting solutions become <i>singular</i>. Totally nonnegative elements are parametrized by the <img>-diagrams introduced by Postnikov. We show that the resulting singular solutions can be parametrized by Go-diagrams, which extend <img>-diagrams and arise in the Deodhar decomposition of the Grassmannian.\u0000</p></div>","PeriodicalId":685,"journal":{"name":"Letters in Mathematical Physics","volume":"116 5","pages":""},"PeriodicalIF":1.6,"publicationDate":"2026-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149132500","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Spectral structure of the mixed Hessian of the dispersionless Toda (tau )-function","authors":"Oleg Alekseev","doi":"10.1007/s11005-026-02170-9","DOIUrl":"10.1007/s11005-026-02170-9","url":null,"abstract":"<div><p>We study the mixed Hessian of the dispersionless Toda <span>(tau )</span>-function for the one-harmonic <span>(s)</span>-fold symmetric conformal map <span>(f(w)=rbigl (w+zeta w^{1-s}bigr ))</span>, where <span>(r>0)</span> is the exterior conformal radius and <span>(zeta >0)</span> is the dimensionless shape parameter. This Hessian is the susceptibility matrix generated by the inverse conformal map. Our spectral statements are formulated for its weighted symmetry-block realizations on a fixed Hilbert space. In that realization, the first spectral transition occurs at the analytic threshold <span>(zeta _c=(s-1)^{s-1}/s^s)</span>, where the dominant square-root singularity of the inverse map reaches the circle <span>(|z|=r)</span>, rather than at the geometric threshold <span>(zeta _{textrm{univ}}=1/(s-1))</span>, where univalence fails. After symmetry decomposition and weighted realization, each block develops exactly one logarithmically diverging eigenvalue as <span>(zeta uparrow zeta _c)</span>, while the remaining spectrum stays bounded and converges to a compact limit. The instability is therefore rank one in every symmetry sector of the weighted block theory. We then continue the scalar Gram generating functions beyond <span>(zeta _c)</span>. They are generalized hypergeometric functions on the slit plane <span>(mathbb {C}{setminus }[zeta _c^2,infty ))</span>, their branch-point expansion contains the logarithmic term responsible for the divergence, and in the range <span>(1le ple s)</span> they admit Cauchy–Stieltjes and Jacobi-matrix realizations. In particular, the continued scalar quantities remain regular at <span>(zeta _{textrm{univ}})</span>, so the analytic spectral transition strictly precedes the geometric breakdown of univalence.</p></div>","PeriodicalId":685,"journal":{"name":"Letters in Mathematical Physics","volume":"116 5","pages":""},"PeriodicalIF":1.6,"publicationDate":"2026-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149132170","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}