Approximate Lifshitz Law for the Zero-Temperature Stochastic Ising Model in any Dimension

We study the Glauber dynamics for the zero-temperature stochastic Ising model in dimension d ≥ 4 with “plus” boundary condition. Let ${\mathcal{T}_+}$ be the time needed for an hypercube of size L entirely filled with “minus” spins to become entirely “plus”. We prove that ${\mathcal{T}_+}$ is O(L ²(log L) ^c ) for some constant c, not depending on the dimension. This brings further rigorous justification for the so-called “Lifshitz law” ${\mathcal{T}_{+} = O(L^{2})}$ (Fischer and Huse in Phys Rev B 35:6841–6848, 1987; Lifshitz in Sov Phys JETP 15:939–942, 1962) conjectured on heuristic grounds. The key point of our proof is to use the detailed knowledge that we have on the three-dimensional problem: results for fluctuation of monotone interfaces at equilibrium and mixing time for monotone interfaces dynamics extracted from Caputo et al. (Comm Pure Appl Math 64:778–831, 2011) to get the result in higher dimension.     

On the Geodesic Hypothesis in General Relativity

In this paper, we give a rigorous derivation of Einstein’s geodesic hypothesis in general relativity. We use small material bodies ${\phi^\epsilon}$ governed by the nonlinear Klein–Gordon equations to approximate the test particle. Given a vacuum spacetime ${([0, T]\times\mathbb{R}^3, h)}$ , we consider the initial value problem for the Einstein-scalar field system. For all sufficiently small ε and δ ≤ ε ^q , q > 1, where δ, ε are the amplitude and size of the particle, we show the existence of the solution ${([0, T]\times\mathbb{R}^3, g, \phi^\epsilon)}$ to the Einstein-scalar field system with the property that the energy of the particle ${\phi^\epsilon}$ is concentrated along a timelike geodesic. Moreover, the gravitational field produced by ${\phi^\epsilon}$ is negligibly small in C ¹, that is, the spacetime metric g is C ¹ close to the given vacuum metric h. These results generalize those obtained by Stuart in (Ann Sci École Norm Sup (4) 37(2):312–362, 2004, J Math Pures Appl (9) 83(5):541–587, 2004).     

Bifurcation analysis and the travelling wave solutions of the Klein–Gordon–Zakharov equations

In this paper, we investigate the bifurcations and dynamic behaviour of travelling wave solutions of the Klein–Gordon–Zakharov equations given in Shang et al, Comput. Math. Appl. 56, 1441 (2008). Under different parameter conditions, we obtain some exact explicit parametric representations of travelling wave solutions by using the bifurcation method (Feng et al, Appl. Math. Comput. 189, 271 (2007); Li et al, Appl. Math. Comput. 175, 61 (2006)).     

Note on Solutions of the Strominger System from Unitary Representations of Cocompact Lattices of {SL(2,\mathbb{C})}

This note is motivated by a recently published paper (Biswas and Mukherjee in Commun Math Phys 322(2):373–384, 2013). We prove a no-go result for the existence of suitable solutions of the Strominger system in a compact complex parallelizable manifold \({M = G/\Gamma}\) . For this, we assume G to be non-abelian, the Hermitian metric to be induced from a right invariant metric on G, the Bianchi identity to be satisfied using the Chern connection and furthermore the gauge field to be flat. In Biswas and Mukherjee (Commun Math Phys 322(2):373–384, 2013) it is claimed that one such solution exists on \({SL(2, \mathbb{C})/\Gamma}\) . Our result contradicts the main result in Biswas and Mukherjee (Commun Math Phys 322(2):373–384, 2013).     

n-Orthodistributivity in Orthomodular Lattices

A useful generalization of distributivity in lattices n-distributivity, \(n \in \mathbb{N}\) , was introduced in Huhn (Acta Sci. Math. 33:297–305, 1972). In Mayet and Roddy (Contrib. Gen. Algebra 5:285–294, 1987), ‘orthogonalized’ versions, n-orthodistributivity, \(n \in \mathbb{N}\) , of these equations were introduced and discussed. The discussion and results of Mayet and Roddy (Contrib. Gen. Algebra 5:285–294, 1987) centered on the class of modular ortholattices. In this paper we discuss and present some preliminary results for these conditions in orthomodular lattices. In particular, we completely classify the n-(ortho)distributive orthomodular lattices arising from Greechie’s classical 1971 construction, and we prove that a certain simple atomless orthomodular lattice, presented in Roddy (Algebra Univers. 29:564–597, 1992), is 4-orthodistributive. It is not 3-orthodistributive.     

Asymptotic Expansion of β Matrix Models in the One-cut Regime

We prove the existence of a 1/N expansion to all orders in β matrix models with a confining, offcritical potential corresponding to an equilibrium measure with a connected support. Thus, the coefficients of the expansion can be obtained recursively by the “topological recursion” derived in Chekhov and Eynard (JHEP 0612:026, 2006). Our method relies on the combination of a priori bounds on the correlators and the study of Schwinger-Dyson equations, thanks to the uses of classical complex analysis techniques. These a priori bounds can be derived following (Boutet de Monvel et al. in J Stat Phys 79(3–4):585–611, 1995; Johansson in Duke Math J 91(1):151–204, 1998; Kriecherbauer and Shcherbina in Fluctuations of eigenvalues of matrix models and their applications, 2010) or for strictly convex potentials by using concentration of measure (Anderson et al. in An introduction to random matrices, Sect. 2.3, Cambridge University Press, Cambridge, 2010). Doing so, we extend the strategy of Guionnet and Maurel-Segala (Ann Probab 35:2160–2212, 2007), from the hermitian models (β = 2) and perturbative potentials, to general β models. The existence of the first correction in 1/N was considered in Johansson (1998) and more recently in Kriecherbauer and Shcherbina (2010). Here, by taking similar hypotheses, we extend the result to all orders in 1/N.     

Bloch Bundles, Marzari-Vanderbilt Functional and Maximally Localized Wannier Functions

We consider a periodic Schrödinger operator and the composite Wannier functions corresponding to a relevant family of its Bloch bands, separated by a gap from the rest of the spectrum. We study the associated localization functional introduced in Marzari and Vanderbilt (Phys Rev B 56:12847–12865, 1997) and we prove some results about the existence and exponential localization of its minimizers, in dimension ${d \leq 3}$ d ≤ 3 . The proof exploits ideas and methods from the theory of harmonic maps between Riemannian manifolds.     

Fourth Moment Theorem and q-Brownian Chaos

In 2005, Nualart and Peccati (Ann Probab 33(1):177–193, 2005) proved the so-called Fourth Moment Theorem asserting that, for a sequence of normalized multiple Wiener-Itô integrals to converge to the standard Gaussian law, it is necessary and sufficient that its fourth moment tends to 3. A few years later, Kemp et al. (Ann Probab 40(4):1577–1635, 2011) extended this theorem to a sequence of normalized multiple Wigner integrals, in the context of the free Brownian motion. The q-Brownian motion, ${q \in (-1, 1]}$ , introduced by the physicists Frisch and Bourret (J Math Phys 11:364–390, 1970) in 1970 and mathematically studied by Bo?ejko and Speicher (Commun Math Phys 137:519–531, 1991), interpolates between the classical Brownian motion (q = 1) and the free Brownian motion (q = 0), and is one of the nicest examples of non-commutative processes. The question we shall solve in this paper is the following: what does the Fourth Moment Theorem become when dealing with a q-Brownian motion?     

The Z=Z(t/z)-Type Plane Wave Solutions of the Field Equations of General Relativity in a Plane Symmetric Space-Time

Taub (Ann. Math., 53:472?C490, 1951) has studied plane symmetry in Riemannian space-time by considering empty space-time admitting a three parameter group of motions. In this paper, we have deduced the line element of such a space-time for Z=Z(t/z)-type plane gravitational waves using suitable transformations following the concept of Takeno (Sci. Rep. Inst. Theor. Phys. Hiroshima Univ. 1, 1961), Lal and Ali (Tensor 20:281?C302, 1969). Furthermore it has been shown that the deduced space-time admit plane wave solutions of the field equations of general relativity containing electromagnetic terms. Also we have studied electromagnetic field except gauge transformation with particular cases with respect to ??.     

Tail Asymptotics of Free Path Lengths for the Periodic Lorentz Process: On Dettmann’s Geometric Conjectures

In the simplest case, consider a \({\mathbb{Z}^d}\) -periodic (d ≥ 3) arrangement of balls of radii < 1/2, and select a random direction and point (outside the balls). According to Dettmann’s first conjecture, the probability that the so determined free flight (until the first hitting of a ball) is larger than t >  > 1 is \({\sim\frac{C}{t}}\) , where C is explicitly given by the geometry of the model. In its simplest form, Dettmann’s second conjecture is related to the previous case with tangent balls (of radii 1/2). The conjectures are established in a more general setup: for \({\mathcal{L}}\) -periodic configuration of—possibly intersecting—convex bodies with \({\mathcal{L}}\) being a non-degenerate lattice. These questions are related to Pólya’s visibility problem (Arch Math Phys Ser 2:135–142, 1918), to theories of Bourgain et al. (Commun Math Phys 190:491–508,1998), and of Marklof–Strömbergsson (Ann Math 172:1949–2033,2010). The results also provide the asymptotic covariance of the periodic Lorentz process assuming it has a limit in the super-diffusive scaling, a fact if d = 2 and the horizon is infinite.     

Cauchy Problem for Dissipative Hölder Solutions to the Incompressible Euler Equations

We consider solutions to the Cauchy problem for the incompressible Euler equations on the 3-dimensional torus which are continuous or Hölder continuous for any exponent ${\theta < \frac{1}{16}}$ . Using the techniques introduced in De Lellis and Székelyhidi (Inventiones Mathematicae 9:377–407, 2013; Dissipative Euler flows and Onsager’s conjecture, 2012), we prove the existence of infinitely many (Hölder) continuous initial vector fields starting from which there exist infinitely many (Hölder) continuous solutions with preassigned total kinetic energy.     

The McKean–Vlasov Equation in Finite Volume

We study the McKean–Vlasov equation on the finite tori of length scale L in d-dimensions. We derive the necessary and sufficient conditions for the existence of a phase transition, which are based on the criteria first uncovered in Gates and Penrose (Commun. Math. Phys. 17:194–209, 1970) and Kirkwood and Monroe (J. Chem. Phys. 9:514–526, 1941). Therein and in subsequent works, one finds indications pointing to critical transitions at a particular model dependent value, θ ^? of the interaction parameter. We show that the uniform density (which may be interpreted as the liquid phase) is dynamically stable for θ<θ ^? and prove, abstractly, that a critical transition must occur at θ=θ ^? . However for this system we show that under generic conditions—L large, d≥2 and isotropic interactions—the phase transition is in fact discontinuous and occurs at some $\theta_{\text{T}}<\theta^{\sharp }$ . Finally, for H-stable, bounded interactions with discontinuous transitions we show that, with suitable scaling, the $\theta_{\text{T}}(L)$ tend to a definitive non-trivial limit as L→∞.     

Hitting Matrix and Domino Tiling with Diagonal Impurities

As a continuation to our previous work (Nakano and Sadahiro in Fundam. Inform. 117:249–264, 2012; Nakano and Sadahiro in J. Stat. Phys. 139(4):565–597, 2010), we consider the domino tiling problem with impurities. (1) If we have more than two impurities on the boundary, we can compute the number of corresponding perfect matchings by using the hitting matrix method (Fomin in Trans. Am. Math. Soc. 353(9):3563–3583, 2001). (2) We have an alternative proof of the main result in Nakano and Sadahiro (Fundam. Inform. 117:249–264, 2012) and result in (1) above using the formula by Kenyon and Wilson (Trans. Am. Math. Soc. 363(3):1325–1364, 2011; Electron. J. Comb. 16(1):112, 2009) of counting the number of groves on circular planar graphs. (3) We study the behavior of the probability of finding the impurity at a given site when the size of the graph tends to infinity, as well as the scaling limit of those.     

4D Einstein equations in a 5D general Kaluza–Klein space

Based on the new point of view on space–time–matter theory developed in our paper (Bejancu, Gen Rel Grav, 2013), we obtain the $4D$ 4 D Einstein equations in a general $5D$ 5 D Kaluza–Klein space with electromagnetic potentials. In particular, we recover the $4D$ 4 D Einstein equations obtained by Wesson and Ponce de Leon (J Math Phys 33:3883, 1992) in case the electromagnetic potentials vanish identically on $\bar{M}$ M ¯ . The Riemannian horizontal connection and the $4D$ 4 D tensor calculus on $\bar{M}$ M ¯ , are the main tools in the study.     

Multilocal Fermionization

We present a simple isomorphism between the algebra of one real chiral Fermi field and the algebra of n real chiral Fermi fields. The isomorphism preserves the vacuum state. This is possible by a “change of localization”, and gives rise to new multilocal symmetries generated by the corresponding multilocal current and stress–energy tensor. The result gives a common underlying explanation of several remarkable recent results on the representation of the free Bose field in terms of free Fermi fields (Anguelova, arXiv:1112.3913, 2011; Anguelova, arXiv:1206.4026, 2012), and on the modular theory of the free Fermi algebra in disjoint intervals (Casini and Huerta, Class Quant Grav 26:185005, 2009; Longo et al., Rev Math Phys 22:331–354, 2010)     

Quantum Random Walks with General Particle States

A convergence theorem is obtained for quantum random walks with particles in an arbitrary normal state. This unifies and extends previous work on repeated-interactions models, including that of Attal and Pautrat (Ann Henri Poincaré 7:59–104 2006) and Belton (J Lond Math Soc 81:412–434, 2010; Commun Math Phys 300:317–329, 2010). When the random-walk generator acts by ampliation and either multiplication or conjugation by a unitary operator, it is shown that the quantum stochastic cocycle which arises in the limit is driven by a unitary process.     

A Note on Permutation Twist Defects in Topological Bilayer Phases

We present a mathematical derivation of some of the most important physical quantities arising in topological bilayer systems with permutation twist defects as introduced by Barkeshli et al. (Phys Rev B 87:045130_1-23, 2013). A crucial tool is the theory of permutation equivariant modular functors developed by Barmeier et al. (Int Math Res Notices 2010:3067–3100, 2010; Transform Groups 16:287–337, 2011).     

Threshold Phenomenon for the Quintic Wave Equation in Three Dimensions

For the critical focusing wave equation ${\square u = u^5 \, {\rm on} \, \mathbb{R}^{3+1}}$ in the radial case, we establish the role of the “center stable” manifold ${\Sigma}$ constructed in Krieger and Schlag (Am J Math 129(3):843–913, 2007) near the ground state (W, 0) as a threshold between blowup and scattering to zero, establishing a conjecture going back to numerical work by Bizoń et al. (Nonlinearity 17(6):2187–2201, 2004). The underlying topology is stronger than the energy norm.