{"title":"Characterization of k-Positive Maps","authors":"Tomasz Młynik, Hiroyuki Osaka, Marcin Marciniak","doi":"10.1007/s00220-025-05250-4","DOIUrl":"10.1007/s00220-025-05250-4","url":null,"abstract":"<div><p>We present a general characterization of <i>k</i>-positivity for a positive map in terms of the estimation of the Ky Fan norm of the matrix constructed from the Kraus operators of the associated completely positive map. Combining this with the result given by Takasaki and Tomiyama we construct a family of positive maps between matrix algebras of different dimensions depending on a parameter. The estimate bounds on the parameter to obtain the <i>k</i>-positivity are better than those derived from the spectral conditions considered by Chruściński and Kossakowski (Comm. Math. Phys. 290, 1051-1064, 2009). We further look with special attention at the case where we give the precise bound for the regions of decomposability.</p></div>","PeriodicalId":522,"journal":{"name":"Communications in Mathematical Physics","volume":"406 3","pages":""},"PeriodicalIF":2.2,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143430808","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 a Variational Problem Related to the Cwikel–Lieb–Rozenblum and Lieb–Thirring Inequalities","authors":"Thiago Carvalho Corso, Tobias Ried","doi":"10.1007/s00220-024-05216-y","DOIUrl":"10.1007/s00220-024-05216-y","url":null,"abstract":"<div><p>We explicitly solve a variational problem related to upper bounds on the optimal constants in the Cwikel–Lieb–Rozenblum (CLR) and Lieb–Thirring (LT) inequalities, which has recently been derived in Hundertmark et al. (Invent Math 231:111–167, 2023. https://doi.org/10.1007/s00222-022-01144-7) and Frank et al. (Eur Math Soc 23(8):2583–2600, 2021. https://doi.org/10.1090/pspum/104/01877). We achieve this through a variational characterization of the <span>(L^1)</span> norm of the Fourier transform of a function and duality, from which we obtain a reformulation in terms of a variant of the Hadamard three lines lemma. By studying Hardy-like spaces of holomorphic functions in a strip in the complex plane, we are able to provide an analytic formula for the minimizers, and use it to get the best possible upper bounds for the optimal constants in the CLR and LT inequalities achievable by the method of Hundertmark et al. (Invent Math 231:111–167, 2023. https://doi.org/10.1007/s00222-022-01144-7) and Frank et al. (Eur Math Soc 23(8):2583–2600, 2021. https://doi.org/10.1090/pspum/104/01877).</p></div>","PeriodicalId":522,"journal":{"name":"Communications in Mathematical Physics","volume":"406 3","pages":""},"PeriodicalIF":2.2,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00220-024-05216-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143362060","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Crystallization of (hbox {C}^*)-Algebras","authors":"Marcelo Laca, Sergey Neshveyev, Makoto Yamashita","doi":"10.1007/s00220-024-05212-2","DOIUrl":"10.1007/s00220-024-05212-2","url":null,"abstract":"<div><p>Given a <span>(hbox {C}^*)</span>-algebra <i>A</i> with an almost periodic time evolution <span>(sigma )</span>, we define a new <span>(hbox {C}^*)</span>-algebra <span>(A_c)</span>, which we call the crystal of <span>((A,sigma ))</span>, that represents the zero temperature limit of <span>((A, sigma ))</span>. We prove that there is a one-to-one correspondence between the ground states of <span>((A,sigma ))</span> and the states on <span>(A_c)</span>, justifying the name. In order to investigate further the relation between low temperature equilibrium states on <i>A</i> and traces on <span>(A_c)</span>, we define a Fock module <span>(mathcal {F})</span> over the crystal and construct a vacuum representation of <i>A</i> on <span>(mathcal {F})</span>. This allows us to show, under relatively mild assumptions, that for sufficiently large inverse temperatures <span>(beta )</span> the <span>(sigma )</span>-<span>(hbox {KMS}_beta )</span>-states on <i>A</i> are induced from traces on <span>(A_c)</span> by means of the Fock module. In the second part, we compare the K-theoretic structures of <i>A</i> and <span>(A_c)</span>. Previous work by various authors suggests that they have (rationally) isomorphic K-groups. We analyze this phenomenon in detail, confirming it under favorable conditions, but showing that, in general, there is apparently no easy way to relate these groups. As examples, we discuss in particular Exel’s results on semi-saturated circle actions, and recent results of Miller on the K-theory of inverse semigroup <span>(hbox {C}^*)</span>-algebras. In relation to the latter, we introduce the notion of a scale <i>N</i> on an inverse semigroup <i>I</i> and define a new inverse semigroup <span>(I_c)</span>, which we call the crystal of (<i>I</i>, <i>N</i>).</p></div>","PeriodicalId":522,"journal":{"name":"Communications in Mathematical Physics","volume":"406 3","pages":""},"PeriodicalIF":2.2,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00220-024-05212-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143361926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 Tail Distribution of the Partition Function for Directed Polymers in the Weak Disorder Phase","authors":"Stefan Junk, Hubert Lacoin","doi":"10.1007/s00220-025-05246-0","DOIUrl":"10.1007/s00220-025-05246-0","url":null,"abstract":"<div><p>We investigate the upper tail distribution of the partition function of the directed polymer in a random environment on <span>({{mathbb {Z}}} ^d)</span> in the weak disorder phase. We show that the distribution of the infinite volume partition function <span>(W^{beta }_{infty })</span> displays a power-law decay, with an exponent <span>(p^*(beta )in [1+frac{2}{d},infty ))</span>. We also prove that the distribution of the suprema of the point-to-point and point-to-line partition functions display the same behavior. On the way to these results, we prove a technical estimate of independent interest: the <span>(L^p)</span>-norm of the partition function at the time when it overshoots a high value <i>A</i> is comparable to <i>A</i>. We use this estimate to extend the validity of many recent results that were proved under the assumption that the environment is upper bounded.</p></div>","PeriodicalId":522,"journal":{"name":"Communications in Mathematical Physics","volume":"406 3","pages":""},"PeriodicalIF":2.2,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143184790","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Ilka Brunner, Nils Carqueville, Pantelis Fragkos, Daniel Roggenkamp
{"title":"Truncated Affine Rozansky–Witten Models as Extended Defect TQFTs","authors":"Ilka Brunner, Nils Carqueville, Pantelis Fragkos, Daniel Roggenkamp","doi":"10.1007/s00220-024-05164-7","DOIUrl":"10.1007/s00220-024-05164-7","url":null,"abstract":"<div><p>We apply the cobordism hypothesis with singularities to the case of affine Rozansky–Witten models, providing a construction of extended TQFTs that includes all line and surface defects. On a technical level, this amounts to proving that the associated homotopy 2-category is pivotal, and to systematically employing its 3-dimensional graphical calculus. This in particular allows us to explicitly calculate state spaces for surfaces with arbitrary defect networks. As specific examples we discuss symmetry defects which can be used to model non-trivial background gauge fields, as well as boundary conditions.\u0000</p></div>","PeriodicalId":522,"journal":{"name":"Communications in Mathematical Physics","volume":"406 2","pages":""},"PeriodicalIF":2.2,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00220-024-05164-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143109631","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
K. Constantineau, C. García-Azpeitia, L. C. García-Naranjo, J.-P. Lessard
{"title":"Determination of Stable Branches of Relative Equilibria of the N-Vortex Problem on the Sphere","authors":"K. Constantineau, C. García-Azpeitia, L. C. García-Naranjo, J.-P. Lessard","doi":"10.1007/s00220-024-05220-2","DOIUrl":"10.1007/s00220-024-05220-2","url":null,"abstract":"<div><p>We consider the <i>N</i>-vortex problem on the sphere assuming that all vorticities have equal strength. We investigate relative equilibria (RE) consisting of <i>n</i> latitudinal rings which are uniformly rotating about the vertical axis with angular velocity <span>(omega )</span>. Each such ring contains <i>m</i> vortices placed at the vertices of a concentric regular polygon and we allow the presence of additional vortices at the poles. We develop a framework to prove existence and orbital stability of branches of RE of this type parametrised by <span>(omega )</span>. Such framework is implemented to rigorously determine and prove stability of segments of branches using computer-assisted proofs. This approach circumvents the analytical complexities that arise when the number of rings <span>(nge 2)</span> and allows us to give several new rigorous results. We exemplify our method providing new contributions consisting of the determination of enclosures and proofs of stability of several equilibria and RE for <span>(5le Nle 12)</span>.</p></div>","PeriodicalId":522,"journal":{"name":"Communications in Mathematical Physics","volume":"406 2","pages":""},"PeriodicalIF":2.2,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143109632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Generalized Positive Energy Representations of the Group of Compactly Supported Diffeomorphisms","authors":"Bas Janssens, Milan Niestijl","doi":"10.1007/s00220-024-05226-w","DOIUrl":"10.1007/s00220-024-05226-w","url":null,"abstract":"<div><p>Motivated by asymptotic symmetry groups in general relativity, we consider projective unitary representations <span>(overline{rho })</span> of the Lie group <span>({{,textrm{Diff},}}_c(M))</span> of compactly supported diffeomorphisms of a smooth manifold <i>M</i> that satisfy a so-called generalized positive energy condition. In particular, this captures representations that are in a suitable sense compatible with a KMS state on the von Neumann algebra generated by <span>(overline{rho })</span>. We show that if <i>M</i> is connected and <span>(dim (M) > 1)</span>, then any such representation is necessarily trivial on the identity component <span>({{,textrm{Diff},}}_c(M)_0)</span>. As an intermediate step towards this result, we determine the continuous second Lie algebra cohomology <span>(H^2_textrm{ct}(mathcal {X}_c(M), mathbb {R}))</span> of the Lie algebra of compactly supported vector fields. This is subtly different from Gelfand–Fuks cohomology in view of the compact support condition.</p></div>","PeriodicalId":522,"journal":{"name":"Communications in Mathematical Physics","volume":"406 2","pages":""},"PeriodicalIF":2.2,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00220-024-05226-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143109307","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Regularity of Conjugacies of Linearizable Generalized Interval Exchange Transformations","authors":"Selim Ghazouani, Corinna Ulcigrai","doi":"10.1007/s00220-024-05197-y","DOIUrl":"10.1007/s00220-024-05197-y","url":null,"abstract":"<div><p>We consider generalized interval exchange transformations (GIETs) of <span>(dge 2)</span> intervals which are <i>linearizable</i>, i.e. differentiably conjugated to standard interval exchange maps (IETs) via a diffeomorphism <i>h</i> of [0, 1] and study the regularity of the conjugacy <i>h</i>. Using a renormalization operator obtained accelerating Rauzy–Veech induction, we show that, under a full measure condition on the IET obtained by linearization, if the orbit of the GIET under renormalization converges exponentially fast in a <span>({mathcal {C}}^2)</span> distance to the subspace of IETs, there exists an exponent <span>(0<alpha <1)</span> such that <i>h</i> is <span>({mathcal {C}}^{1+alpha })</span>. Combined with the results proved by the authors in [4], this implies in particular the following improvement of the rigidity result in genus two proved in [4] (from <span>({mathcal {C}}^1)</span> to <span>({mathcal {C}}^{1+alpha })</span> rigidity): for almost every irreducible IET <span>(T_0 )</span> with <span>(d=4)</span> or <span>(d=5)</span>, for any GIET which is topologically conjugate to <span>(T_0)</span> via a homeomorphism <i>h</i> and has vanishing boundary, the topological conjugacy <i>h</i> is actually a <span>({mathcal {C}}^{1+alpha })</span> diffeomorphism, i.e. a diffeomorphism <i>h</i> with derivative <i>Dh</i> which is <span>(alpha )</span>-Hölder continuous.</p></div>","PeriodicalId":522,"journal":{"name":"Communications in Mathematical Physics","volume":"406 2","pages":""},"PeriodicalIF":2.2,"publicationDate":"2025-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00220-024-05197-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142995304","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Ángela Capel, Massimo Moscolari, Stefan Teufel, Tom Wessel
{"title":"From Decay of Correlations to Locality and Stability of the Gibbs State","authors":"Ángela Capel, Massimo Moscolari, Stefan Teufel, Tom Wessel","doi":"10.1007/s00220-024-05198-x","DOIUrl":"10.1007/s00220-024-05198-x","url":null,"abstract":"<div><p>We show that whenever the Gibbs state of a quantum spin system satisfies decay of correlations, then it is stable, in the sense that local perturbations affect the Gibbs state only locally, and it satisfies local indistinguishability, i.e. it exhibits local insensitivity to system size. These implications hold in any dimension, require only locality of the Hamiltonian, and are based on Lieb–Robinson bounds and on a detailed analysis of the locality properties of the quantum belief propagation for Gibbs states. To demonstrate the versatility of our approach, we explicitly apply our results to several physically relevant models in which the decay of correlations is either known to hold or is proved by us. These include Gibbs states of one-dimensional spin chains with polynomially decaying interactions at any temperature, and high-temperature Gibbs states of quantum spin systems with finite-range interactions in any dimension. We also prove exponential decay of correlations above a threshold temperature for Gibbs states of one-dimensional finite spin chains with translation-invariant and exponentially decaying interactions, and then apply our general results.</p></div>","PeriodicalId":522,"journal":{"name":"Communications in Mathematical Physics","volume":"406 2","pages":""},"PeriodicalIF":2.2,"publicationDate":"2025-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00220-024-05198-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142995303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 Modular Invariance of Quantum Affine W-Algebras","authors":"Victor G. Kac, Minoru Wakimoto","doi":"10.1007/s00220-024-05223-z","DOIUrl":"10.1007/s00220-024-05223-z","url":null,"abstract":"<div><p>We find modular transformations of normalized characters for the following <i>W</i>-algebras: (a) <span>(W_k^{min}(mathfrak {g}), text {where } mathfrak {g}=D_n (nge 4), text {or } E_6, E_7, E_8,)</span> and <i>k</i> is a negative integer <span>(ge -2)</span>, or <span>(ge -frac{h^vee }{6}-1)</span>, respectively; (b) quantum Hamiltonian reduction of the <span>(hat{mathfrak {g}})</span>-module <span>(L(k Lambda _0))</span>, where <span>(mathfrak {g})</span> is a simple Lie algebra, <i>f</i> is its non-zero nilpotent element, and <i>k</i> is a principal admissible level with the denominator <span>(u>theta (x))</span>, where 2<i>x</i> is the Dynkin characteristic of <i>f</i>, and <span>(theta )</span> is the highest root of <span>(mathfrak {g})</span>. We prove that these vertex algebras are modular invariant. A conformal vertex algebra <i>V</i> is called modular invariant if its character <span>(tr_V q^{L_0-c/24})</span> converges to a holomorphic modular function in the complex upper half-plane on a congruence subgroup. We find explicit formulas for their characters. Modular invariance of <i>V</i> is important since, in particular, conjecturally it implies that <i>V</i> is simple, and that <i>V</i> is rational, provided that it is lisse.</p></div>","PeriodicalId":522,"journal":{"name":"Communications in Mathematical Physics","volume":"406 2","pages":""},"PeriodicalIF":2.2,"publicationDate":"2025-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142995308","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}