{"title":"Sharpness of the Phase Transition for the Orthant Model","authors":"Thomas Beekenkamp","doi":"10.1007/s11040-021-09408-z","DOIUrl":"10.1007/s11040-021-09408-z","url":null,"abstract":"<div><p>The orthant model is a directed percolation model on <span>(mathbb {Z}^{d})</span>, in which all clusters are infinite. We prove a sharp threshold result for this model: if <i>p</i> is larger than the critical value above which the cluster of 0 is contained in a cone, then the shift from 0 that is required to contain the cluster of 0 in that cone is exponentially small. As a consequence, above this critical threshold, a shape theorem holds for the cluster of 0, as well as ballisticity of the random walk on this cluster.</p></div>","PeriodicalId":694,"journal":{"name":"Mathematical Physics, Analysis and Geometry","volume":"24 4","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11040-021-09408-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4918467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Kasteleyn Theorem, Geometric Signatures and KP-II Divisors on Planar Bipartite Networks in the Disk","authors":"Simonetta Abenda","doi":"10.1007/s11040-021-09405-2","DOIUrl":"10.1007/s11040-021-09405-2","url":null,"abstract":"<div><p>Maximal minors of Kasteleyn sign matrices on planar bipartite graphs in the disk count dimer configurations with prescribed boundary conditions, and the weighted version of such matrices provides a natural parametrization of the totally non–negative part of real Grassmannians (Postnikov et al. J. Algebr. Combin. <b>30</b>(2), 173–191, 2009; Lam J. Lond. Math. Soc. (2) <b>92</b>(3), 633–656, 2015; Lam 2016; Speyer 2016; Affolter et al. 2019). In this paper we provide a geometric interpretation of such variant of Kasteleyn theorem: a signature is Kasteleyn if and only if it is geometric in the sense of Abenda and Grinevich (2019). We apply this geometric characterization to explicitly solve the associated system of relations and provide a new proof that the parametrization of positroid cells induced by Kasteleyn weighted matrices coincides with that of Postnikov boundary measurement map. Finally we use Kasteleyn system of relations to associate algebraic geometric data to KP multi-soliton solutions. Indeed the KP wave function solves such system of relations at the nodes of the spectral curve if the dual graph of the latter represents the soliton data. Therefore the construction of the divisor is automatically invariant, and finally it coincides with that in Abenda and Grinevich (Sel. Math. New Ser. <b>25</b>(3), 43, 2019; Abenda and Grinevich 2020) for the present class of graphs.</p></div>","PeriodicalId":694,"journal":{"name":"Mathematical Physics, Analysis and Geometry","volume":"24 4","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11040-021-09405-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4556725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Sums of Two-Parameter Deformations of Multiple Polylogarithms","authors":"Masaki Kato","doi":"10.1007/s11040-021-09407-0","DOIUrl":"10.1007/s11040-021-09407-0","url":null,"abstract":"<div><p>In this paper, we introduce a generating function of sums of two-parameter deformations of multiple polylogarithms, denoted by Φ<sub>2</sub>(<i>a</i>;<i>p</i>,<i>q</i>), and study a <i>q</i>-difference equation satisfied by it. We show that this <i>q</i>-difference equation can be solved by expanding Φ<sub>2</sub>(<i>a</i>;<i>p</i>,<i>q</i>) into power series of the parameter <i>p</i> and then using the method of variation of constants. By letting <span>(p rightarrow 0)</span> in the main theorem, we find that the generating function of sums of <i>q</i>-interpolated multiple zeta values can be written in terms of the <i>q</i>-hypergeometric function <sub>3</sub><i>ϕ</i><sub>2</sub>, which is due to Li-Wakabayashi.</p></div>","PeriodicalId":694,"journal":{"name":"Mathematical Physics, Analysis and Geometry","volume":"24 4","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11040-021-09407-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4363914","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"From Auto-Bäcklund Transformations to Auto-Bäcklund Transformations, and Torqued ABS Equations","authors":"Dan-da Zhang, Da-jun Zhang, Peter H. van der Kamp","doi":"10.1007/s11040-021-09406-1","DOIUrl":"10.1007/s11040-021-09406-1","url":null,"abstract":"<div><p>We provide a method which from a given auto-Bäcklund transformation (auto-BT) produces another auto-BT for a different equation. We apply the method to the natural auto-BTs for the ABS quad equations, which gives rise to torqued versions of ABS equations and explains the origin of each auto-BT listed in Atkinson (J. Phys. A: Math. Theor. <b>41</b>(8pp), 135202, 2008). The method is also applied to non-natural auto-BTs for ABS equations, which yields 3D consistent cubes which have not been found in Boll (J. Nonl. Math. Phys. <b>18</b>, 337–365, 2011), and to a multi-quadratic ABS* equation giving rise to a multi-quartic equation.</p></div>","PeriodicalId":694,"journal":{"name":"Mathematical Physics, Analysis and Geometry","volume":"24 4","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4919320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Solitons for the Modified Camassa-Holm Equation and their Interactions Via Dressing Method","authors":"Hui Mao, Yonghui Kuang","doi":"10.1007/s11040-021-09395-1","DOIUrl":"10.1007/s11040-021-09395-1","url":null,"abstract":"<div><p>In this paper, we develop the dressing method to study the modified Camassa-Holm equation with the help of reciprocal transformation and the associated modified Camassa- Holm equation. Based on this method, some different soliton solutions, in particular dark solitons to the modified Camassa-Holm equation are presented and their interactions are investigated.</p></div>","PeriodicalId":694,"journal":{"name":"Mathematical Physics, Analysis and Geometry","volume":"24 4","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11040-021-09395-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5142250","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"New Condition on Uniqueness of Gibbs Measure for Models with Uncountable Set of Spin Values on a Cayley Tree","authors":"F. H. Haydarov","doi":"10.1007/s11040-021-09404-3","DOIUrl":"10.1007/s11040-021-09404-3","url":null,"abstract":"<div><p>In this paper we consider a model with nearest-neighbor interactions with spin space [0, 1] on Cayley trees of order <i>k</i> ⩾ 2. In Yu et al. (2013), a sufficient condition of uniqueness for the splitting Gibbs measure of the model is given. We investigate the sufficient condition of uniqueness and obtain better estimates.</p></div>","PeriodicalId":694,"journal":{"name":"Mathematical Physics, Analysis and Geometry","volume":"24 4","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11040-021-09404-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4809844","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Roberto A. Prado, César R. de Oliveira, Edmundo C. de Oliveira
{"title":"Density of States and Lifshitz Tails for Discrete 1D Random Dirac Operators","authors":"Roberto A. Prado, César R. de Oliveira, Edmundo C. de Oliveira","doi":"10.1007/s11040-021-09403-4","DOIUrl":"10.1007/s11040-021-09403-4","url":null,"abstract":"<div><p>We study the density of states and Lifshitz tails for a family of random Dirac operators on the one-dimensional lattice <span>(mathbb {Z})</span>. These operators consist of the sum of a discrete free Dirac operator with a random potential. The potential is a diagonal matrix formed by two different scalar potentials, which are sequences of independent and identically distributed random variables according to a Borel probability measure of compact support in <span>(mathbb {R})</span>. The existence of the density of state measure for these Dirac operators is obtained through two approaches by finite-volume quantities. By using one of these approaches, we show that the distribution function of the density of states decays exponentially for energies near the spectral band edges, i.e., we establish Lifshitz tails for these operators. Lifshitz tails are established first for Dirac operators restricted to appropriate subspaces of energies and, using this, extended to the full operators, including the occurrence of internal tails in the case of spectral gap.</p></div>","PeriodicalId":694,"journal":{"name":"Mathematical Physics, Analysis and Geometry","volume":"24 3","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4590762","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Solution of the System of Two Coupled First-Order ODEs with Second-Degree Polynomial Right-Hand Sides","authors":"Francesco Calogero, Farrin Payandeh","doi":"10.1007/s11040-021-09400-7","DOIUrl":"10.1007/s11040-021-09400-7","url":null,"abstract":"<div><p>The <i>explicit</i> solution <span>(x_{n}left (tright ) ,)</span> <i>n</i> = 1,2, of the <i>initial-values</i> problem is exhibited of a <i>subclass</i> of the <i>autonomous</i> system of 2 coupled <i>first-order</i> ODEs with <i>second-degree</i> polynomial right-hand sides, hence featuring 12 <i>a priori arbitrary</i> (time-independent) coefficients: \u0000</p><div><div><span>$$ dot{x}_{n}=c_{n1}left( x_{1}right)^{2}+c_{n2}x_{1}x_{2}+c_{n3}left( x_{2}right)^{2}+c_{n4}x_{1}+c_{n5}x_{2}+c_{n6}~,~~~n=1,2~. $$</span></div></div><p> The solution is <i>explicitly</i> provided if the 12 coefficients <i>c</i><sub><i>n</i><i>j</i></sub> (<i>n</i> = 1,2; <i>j</i> = 1,2,3,4,5,6) are expressed by <i>explicitly</i> provided formulas in terms of 10 <i>a priori arbitrary</i> parameters; the <i>inverse</i> problem to express these 10 parameters in terms of the 12 coefficients <i>c</i><sub><i>n</i><i>j</i></sub> is also <i>explicitly</i> solved, but it is found to imply—as it were, <i>a posteriori</i>—that the 12 coefficients <i>c</i><sub><i>n</i><i>j</i></sub> must then satisfy 4 <i>algebraic constraints</i>, which are <i>explicitly</i> exhibited. Special subcases are also identified the <i>general</i> solutions of which are <i>completely periodic</i> with a period independent of the initial data (“isochrony”), or are characterized by additional restrictions on the coefficients <i>c</i><sub><i>n</i><i>j</i></sub> which identify particularly interesting models.</p></div>","PeriodicalId":694,"journal":{"name":"Mathematical Physics, Analysis and Geometry","volume":"24 3","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s11040-021-09400-7","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4668589","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Fundamental solutions and Hadamard states for a scalar field with arbitrary boundary conditions on an asymptotically AdS spacetimes","authors":"Claudio Dappiaggi, Alessio Marta","doi":"10.1007/s11040-021-09402-5","DOIUrl":"10.1007/s11040-021-09402-5","url":null,"abstract":"<div><p>We consider the Klein-Gordon operator on an <i>n</i>-dimensional asymptotically anti-de Sitter spacetime (<i>M</i>,<i>g</i>) together with arbitrary boundary conditions encoded by a self-adjoint pseudodifferential operator on <i>∂</i><i>M</i> of order up to 2. Using techniques from <i>b</i>-calculus and a propagation of singularities theorem, we prove that there exist advanced and retarded fundamental solutions, characterizing in addition their structural and microlocal properties. We apply this result to the problem of constructing Hadamard two-point distributions. These are bi-distributions which are weak bi-solutions of the underlying equations of motion with a prescribed form of their wavefront set and whose anti-symmetric part is proportional to the difference between the advanced and the retarded fundamental solutions. In particular, under a suitable restriction of the class of admissible boundary conditions and setting to zero the mass, we prove their existence extending to the case under scrutiny a deformation argument which is typically used on globally hyperbolic spacetimes with empty boundary.</p></div>","PeriodicalId":694,"journal":{"name":"Mathematical Physics, Analysis and Geometry","volume":"24 3","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s11040-021-09402-5","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4484318","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Bilinear Equation and Additional Symmetries for an Extension of the Kadomtsev–Petviashvili Hierarchy","authors":"Jiaping Lu, Chao-Zhong Wu","doi":"10.1007/s11040-021-09401-6","DOIUrl":"10.1007/s11040-021-09401-6","url":null,"abstract":"<div><p>An extension of the Kadomtsev–Petviashvili (KP) hierarchy defined via scalar pseudo-differential operators was studied in Szablikowski and Blaszak (J. Math. Phys. <b>49</b>(8), 082701, 20, 2008) and Wu and Zhou (J. Geom. Phys. <b>106</b>, 327–341, 2016). In this paper, we represent the extended KP hierarchy into the form of bilinear equation of (adjoint) Baker–Akhiezer functions, and construct its additional symmetries. As a byproduct, we derive the Virasoro symmetries for the constrained KP hierarchies.</p></div>","PeriodicalId":694,"journal":{"name":"Mathematical Physics, Analysis and Geometry","volume":"24 3","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1007/s11040-021-09401-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4238213","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}