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1.
In the framework of the renormalization group and the ɛ-expansion, we propose expressions for the β-function and anomalous
dimensions in terms of renormalized one-irreducible functions. These expressions are convenient for numerical calculations.
We choose the renormalization scheme in which the quantities calculated using R operations are represented by integrals that
do not contain singularities in ɛ. We develop a completely automated calculation system starting from constructing diagrams,
determining relevant subgraphs, combinatorial coefficients, etc., up to determining critical exponents. As an example, we
calculate the critical exponents of the φ
3
model in the order ɛ
4
. 相似文献
2.
Thomas Bartsch 《manuscripta mathematica》1990,66(1):129-152
Let G be a compact Lie group and V a G-module, i.e. a finite-dimensional real vector space on which G acts orthogonally. We
are interested in finding G-orbits of critical points of G-invariant C2-functionals f: SV→—, SV the unit sphere of V. Using a generalization of the Borsuk-Ulam theorem by Komiya [15] we give lower
bounds for the number of critical orbits with a given orbit type. These results are applied to nonlinear eigenvalue problems
which are symmetric with respect to an action of O(3) or a closed subgroup of O(3). 相似文献
3.
We study the global analytic properties of the solutions of a particular family of Painlevé VI equations with the parameters
β=γ=0, δ= and 2α=(2μ-1)2 with arbitrary μ, 2μ≠∈ℤ. We introduce a class of solutions having critical behaviour of algebraic type, and completely compute
the structure of the analytic continuation of these solutions in terms of an auxiliary reflection group in the three dimensional
space. The analytic continuation is given in terms of an action of the braid group on the triples of generators of the reflection
group. We show that the finite orbits of this action correspond to the algebraic solutions of our Painlevé VI equation and
use this result to classify all of them. We prove that the algebraic solutions of our Painlevé VI equation are in one-to-one
correspondence with the regular polyhedra or star-polyhedra in the three dimensional space.
Oblatum 19-III-1999 & 25-XI-1999?Published online: 21 February 2000 相似文献
4.
Richard Sharp 《Geometriae Dedicata》2007,125(1):63-74
Let Γ be a convex co-compact group of isometries of a CAT(−1) space X and let Γ0 be a normal subgroup of Γ. We show that, provided Γ is a free group, a sufficient condition for Γ and Γ0 to have the same critical exponent is that Γ / Γ0 is amenable.
相似文献
5.
N. V. Antonov A. S. Kapustin A. V. Malyshev 《Theoretical and Mathematical Physics》2011,169(1):1470-1480
Using the field theory renormalization group, we study the critical behavior of two systems subjected to turbulent mixing.
The first system, described by the equilibrium model A, corresponds to the relaxational dynamics of a nonconserved order parameter.
The second system is the strongly nonequilibrium reaction-diffusion system, known as the Gribov process or directed percolation
process. The turbulent mixing is modeled by the stochastic Navier-Stokes equation with a random stirring force with the correlator
∞ δ(t − t′)p
4−d−y, where p is the wave number, d is the space dimension, and y is an arbitrary exponent. We show that the systems exhibit various
types of critical behavior depending on the relation between y and d. In addition to known regimes (original systems without
mixing and a passively advected scalar field), we establish the existence of new strongly nonequilibrium universality classes
and calculate the corresponding critical dimensions to the first order of the double expansion in y and ɛ = 4 − d (one-loop approximation). 相似文献
6.
Summary The problem of electric load modelling for low aggregation levels is addressed in this paper. The objective is to obtain good
“demand” and “response” behaviour models of any group of loads in an electric energy distribution system for any of the functional
applications that are beeing considered in the framework of the Distribution Management Systems, aimed to improve the energy
efficiency, reliability and quality of the system. A brief critical revision of the methodologies used for that purpose is
in the paper, and the advantages of using approaches where physical knowledge about the load characteristics is used, are
stated and demonstrated. 相似文献
7.
Pengzi Miao Luen-Fai Tam 《Calculus of Variations and Partial Differential Equations》2009,36(2):141-171
We study the volume functional on the space of constant scalar curvature metrics with a prescribed boundary metric. We derive
a sufficient and necessary condition for a metric to be a critical point, and show that the only domains in space forms, on
which the standard metrics are critical points, are geodesic balls. In the zero scalar curvature case, assuming the boundary
can be isometrically embedded in the Euclidean space as a compact strictly convex hypersurface, we show that the volume of
a critical point is always no less than the Euclidean volume bounded by the isometric embedding of the boundary, and the two
volumes are equal if and only if the critical point is isometric to a standard Euclidean ball. We also derive a second variation
formula and apply it to show that, on Euclidean balls and “small” hyperbolic and spherical balls in dimensions 3 ≤ n ≤ 5, the standard space form metrics are indeed saddle points for the volume functional. 相似文献
8.
Yu. V. Nagrebetskaya 《Algebra and Logic》2000,39(4):276-291
We deal with the decidability problem for first-order theories of a complete linear group GL(n,ℤ) of all integral matrices
of order n ≥ 3. and of a respective complete linear monoid ML(n,ℤ). It is proved that theories ∀? ∧ GL(3,ℤ). ∃∀∧ GL(3,ℤ).
∀? ∧ ML(3,ℤ), and ∃? ∧ ML(3,ℤ) are critical. and that ∃∀ ∧ νGL(n,ℤ) and ∃∀ ∧ML(n,ℤ) are decidable for any n ≥ 3.
Translated fromAlgebra i Logika, Vol. 39, No. 4, pp. 480–504, July–August, 2000. 相似文献
9.
The formalism of projection Hamiltonians is applied to the N-component O(N)-invariant ϕ4 model in the Euclidean and p-adic spaces. We use two versions of the ε-expansion (with ε = 4 − d and with ε = α − 3d/2, where
α is the renormalization group parameter) and evaluate the critical indices ν and η up to the second order of the perturbation
theory. The results for the (4− d)-expansion then coincide with the known results obtained via the quantum-field renormalization-group
methods. Our calculations give evidence that in dimension three, both expansions describe the same non-Gaussian fixed point
of the renormalization group.
__________
Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 146, No. 3, pp. 365–384, March, 2006. 相似文献
10.
A. Bodin 《Commentarii Mathematici Helvetici》2003,78(1):134-152
We give a global version of Lê-Ramanujam μ-constant theorem for polynomials. Let , , be a family of polynomials of n complex variables with isolated singularities, whose coefficients are polynomials in t. We consider the case where some numerical invariants are constant (the affine Milnor number μ(t), the Milnor number at infinity λ(t), the number of critical values, the number of affine critical values, the number of critical values at infinity). Let n=2, we also suppose the degree of the is a constant, then the polynomials and are topologically equivalent. For we suppose that critical values at infinity depend continuously on t, then we prove that the geometric monodromy representations of the are all equivalent.
Received: January 14, 2002 相似文献
11.
A Student-type test is constructed under a condition weaker than normal. We assume that the errors are scale mixtures of normal
random variables and compute the critical values of the suggested s-test. Our s-test is optimal in the sense that if the level
is at most α, then the s-test provides the minimum critical values. (The most important critical values are tabulated at the
end of the paper.) For α ≤.05, the two-sided s-test is identical with Student’s classical t-test. In general, the s-test is
a t-type test, but its degree of freedom should be reduced depending on α. The s-test is applicable for many heavy-tailed
errors, including symmetric stable, Laplace, logistic, or exponential power. Our results explain when and why the P-value
corresponding to the t-statistic is robust if the underlying distribution is a scale mixture of normal distributions. Bibliography:
24 titles.
Published in Zapiski Nauchnykh Seminarov POMI, Vol. 328, 2005, pp. 5–19. 相似文献
12.
Jorge Lauret 《Annals of Global Analysis and Geometry》2006,30(2):107-138
Let (N, γ) be a nilpotent Lie group endowed with an invariant geometric structure (cf. symplectic, complex, hypercomplex or any of their ‘almost’ versions). We define a left invariant Riemannian metric on N compatible with γ to be minimal, if it minimizes the norm of the invariant part of the Ricci tensor among all compatible metrics with the same scalar curvature. We prove that minimal metrics (if any) are unique up to isometry and scaling, they develop soliton solutions for the ‘invariant Ricci’ flow and are characterized as the critical points of a natural variational problem. The uniqueness allows us to distinguish two geometric structures with Riemannian data, giving rise to a great deal of invariants.Our approach proposes to vary Lie brackets rather than inner products; our tool is the moment map for the action of a reductive Lie group on the algebraic variety of all Lie algebras, which we show to coincide in this setting with the Ricci operator. This gives us the possibility to use strong results from geometric invariant theory.Communicated by: Nigel Hitchin (Oxford)
Mathematics Subject Classifications (2000): Primary: 53D05, 53D55; Secondary: 22E25, 53D20, 14L24, 53C30. 相似文献
13.
Henk Bruin Juan Rivera-Letelier Weixiao Shen Sebastian van Strien 《Inventiones Mathematicae》2008,172(3):509-533
In this paper, we study the dynamics of a smooth multimodal interval map f with non-flat critical points and all periodic
points hyperbolic repelling. Assuming that |Dfn(f(c))|→∞ as n→∞ holds for all critical points c, we show that f satisfies the so-called backward contracting property with
an arbitrarily large constant, and that f has an invariant probability μ which is absolutely continuous with respect to Lebesgue
measure and the density of μ belongs to Lp for all p<ℓmax/(ℓmax-1), where ℓmax denotes the maximal critical order of f. In the appendix, we prove that various growth conditions on the derivatives along
the critical orbits imply stronger backward contraction. 相似文献
14.
Shuji Machihara 《NoDEA : Nonlinear Differential Equations and Applications》2007,14(5-6):625-641
The Cauchy problem for the Dirac–Klein–Gordon equation are discussed in one space dimension. Time local and global existence
for solutions with rough data, especially the solutions for Klein–Gordon equation in the critical and super critical Sobolev
norm of [4] are considered. The solutions with general propagation speeds are dealt with.
相似文献
15.
Ingrid Bauer Fabrizio Catanese Fritz Grunewald 《Mediterranean Journal of Mathematics》2006,3(2):121-146
We start discussing the group of automorphisms of the field of complex numbers, and describe, in the special case of polynomials
with only two critical values, Grothendieck’s program of ‘Dessins d’ enfants’, aiming at giving representations of the absolute
Galois group. We describe Chebycheff and Belyi polynomials, and other explicit examples. As an illustration, we briefly treat
difference and Schur polynomials. Then we concentrate on a higher dimensional analogue of the triangle curves, namely, Beauville
surfaces and varieties isogenous to a product. We describe their moduli spaces, and show how the study of these varieties
leads to new interesting questions in the theory of finite (simple) groups.
We would like to thank Fabio Tonoli for helping us with the pictures. 相似文献
16.
E. Miglierina E. Molho M. Rocca 《Journal of Optimization Theory and Applications》2008,138(3):479-496
In this work, we study the critical points of vector functions from ℝ
n
to ℝ
m
with n≥m, following the definition introduced by Smale in the context of vector optimization. The local monotonicity properties of
a vector function around a critical point which are invariant with respect to local coordinate changes are considered. We
propose a classification of critical points through the introduction of a generalized Morse index for a critical point, consisting
of a triplet of nonnegative integers. The proposed index is based on the sign of an appropriate invariant vector-valued second-order
differential. 相似文献
17.
A. G. Sergeev 《Theoretical and Mathematical Physics》2008,157(3):1745-1759
We consider the problem of twistor quantization for the loop space ΩTG of a compact Lie group G. We show that this problem is solvable in the critical dimension.
Dedicated to Vasilii Sergeevich Vladimirov for his 85th birthday
__________
Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 157, No. 3, pp. 450–467, December, 2008. 相似文献
18.
L. Ts. Adzhemyan N. V. Antonov A. N. Vasil'ev 《Theoretical and Mathematical Physics》1999,120(2):1074-1078
Using the renormalization group method and the operator expansion in the Obukhov-Kraichnan model that describes the intermixing
of a passive scalar admixture by a random Gaussian field of velocities with the correlator 〈v(t,x)v(t′,x)〉−〈v(t,x)v(t′,x′)〉∝δ(t−t′)|x−x′|ε, we prove that the anomalous scaling in the inertial interval is caused by the presence of “dangerous” composite operators
(powers of the local dissipation rate) whose negative critical dimensions determine the anomalous exponents. These exponents
are calculated up to the second order of the ε expansion.
Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 120, No. 2, pp. 309–314, August, 1999. 相似文献
19.
We consider the effect of strongly anisotropic turbulent mixing on the critical behavior of two systems: a φ
3
critical dynamics model describing universal properties of metastable states in the vicinity of a firstorder phase transition
and a reaction-diffusion system near the point of a second-order transition between fluctuation and absorption states (a simple
epidemic process or the Gribov process). In both cases, we demonstrate the existence of a new strongly nonequilibrium, anisotropic
scaling regime (universality class) for which both the mixing and the nonlinearity in the order parameter are relevant. We
evaluate the corresponding critical dimensions in the one-loop approximation of the renormalization group. 相似文献
20.
The critical group C(G) of a graph G is a refinement of the number of spanning trees of the graph and is closely connected with the Laplacian matrix. Let r(G) be the minimum number of generators (i.e., the rank) of the group C(G) and β(G) be the number of independent cycles of G. In this paper, some forbidden induced subgraphs are given for r(G) = n − 3 and all graphs with r(G) = β(G) = n − 3 are characterized. 相似文献