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Yoshiaki Maeda

Publications and source records attributed to Yoshiaki Maeda.

At least 19 recordsLinked to original sources
arXiv2025

The Geometry of Loop Spaces V: Fundamental Groups of Geometric Transformation Groups

We use differential forms on loop spaces to prove that the fundamental group of certain geometric transformation groups is infinite. Examples include both finite and infinite dimensional Lie groups. The finite dimensional examples are the conformal group of $S^{4k+1}$ for a family of nonstandard metrics, and the group of pseudo-Hermitian transformations of a compact CR manifold. Infinite dimensional examples include the group of strict contact diffeomorphisms of a regular contact manifold, and other groups coming from symplectic and contact geometry.

math.DG↗
arXiv2025

The Geometry of Loop Spaces IV: Closed Sasakian Manifolds

We prove that a closed regular $(4k+1)$-Sasakian manifold $(M,h_0)$ admits a family of non-isometric metrics $h_ρ, ρ\geq 0,$ such that $π_1({\rm Isom}(M, h_ρ))$, the fundamental group of the isometry group, is infinite for $ρ>0.$ For $M= S^{4k+1}$, this result holds for all $ρ>0$, but fails at $ρ=0.$

math.DG↗
arXiv2025

The Geometry of Loop Spaces II: Characteristic Classes

Using the Wodzicki residue, we build Wodzicki-Chern-Simons (WCS) classes in $H^{2k-1}(LM)$ associated to the residue Chern character on the loop space $LM$ of a Riemannian manifold $M^{2k-1}$. These WCS classes are associated to the $L^2$ connection and the Sobolev $s=1$ connections on $LM.$ The WCS classes detect several families of 5-manifolds whose isometry group has infinite fundamental group. These manifolds are the total spaces of the circle bundles associated to a multiple $pω, |p|\gg 0$, of the Kähler form $ω$ over an integral Kähler surface.

math.DG↗
arXiv2024

The Geometry of Loop Spaces II: Corrections

This paper contains corrections to Madea, Rosenberg, Torres-Ardila, "The Geometry of Loop Spaces II: Characteristic Classes," Advances in Math. (287), 2016, 485-518. The main change is that results about $π_1({\rm Diff}(M))$ are replaced by results about $π_1({\rm Isom}(M))$, where Diff$(M)$, Isom$(M)$ refer to the diffeomorphism and isometry group of the manifold $M$.

math.DG↗
arXiv2023

Symplectic Double Extensions for Restricted Quasi-Frobenius Lie (Super)Algebras

In this paper, we present a method of symplectic double extensions for restricted quasi-Frobenius Lie superalgebras. Certain cocycles in the restricted cohomology represent obstructions to symplectic double extension, which we fully describe. We found a necessary condition for which a restricted quasi-Frobenius Lie superalgebras is a symplectic double extension of a smaller restricted Lie superalgebra. The constructions are illustrated with a few examples.

math.RT↗
arXiv2022

Double and Lagrangian extensions for quasi-Frobenius Lie superalgebras

A Lie superalgebra is called quasi-Frobenius if it admits a closed anti-symmetric non-degenerate bilinear form. We study the notion of double extensions of quasi-Frobenius Lie superalgebra when the form is either orthosymplectic or periplectic. We show that every quasi-Frobenius Lie superalgebra that satisfies certain conditions can be obtained as a double extension of a smaller quasi-Frobenius Lie superalgebra. We classify all 4-dimensional quasi-Frobenius Lie superalgebras, and show that such Lie superalgebras must be solvable. We study the notion of $T^*$-extensions (or Lagrangian extensions) of Lie superalgebras, and show that they are classified by a certain cohomology space we introduce. Several examples are provided to illustrate our construction.

math.RT↗
arXiv2020

The Geometry of Loop Spaces III: Isometry Groups of Contact Manifolds

Let $M_p$ be a circle bundle with first Chern class $p[\omega]$ over a closed $4n$-dimensional integral symplectic manifold $\bigl(\overline{M},\omega\bigr)$. Equivalently, $M_p$ is a closed contact $(4n+1)$-manifold whose Reeb orbits are all closed and have the same period. For a metric $g$ on $M_p$ compatible with the symplectic structure and the geometry of the circle fiber, we use Wodzicki-Chern-Simons forms on the loop space $LM_p$ to prove that $\pi_1({\rm Isom}(M_p,g))$ is infinite for ${|p| \gg 0}$. We also give the first high-dimensional examples of nonvanishing Wodzicki-Pontryagin forms.

math.DG↗
arXiv2015

Traces and Characteristic Classes in Infinite Dimensions

This paper surveys topological results obtained from characteristic classes built from the two types of traces on the algebra of pseudodifferential operators of nonpositive order. The main results are the construction of a universal $\hat A$-polynomial and Chern character that control the $S^1$-index theorem for all circle actions on a fixed vector bundle over a manifold, and $|π_1({\rm Diff}(M^5))| = \infty$, for ${\rm Diff}(M^5)$ the diffeomorphism group of circle bundles $M^5$ with large first Chern class over projective algebraic Kaehler surfaces.

math.DG↗
arXiv2015

Equivariant, string and leading order characteristic classes associated to fibrations

We construct equivariant, string and leading order characteristic classes and Chern-Simons classes for certain infinite rank bundles associated to fibrations occurring in loop spaces, Gromov-Witten theory and gauge theory. Results include a restatement of the S^1 index theorem using equivariant classes on the tangent bundle to loop space; the expression of some GW invariants in terms of string and leading order classes for infinite rank bundles over moduli spaces of pseudoholomorphic curves for semipositive symplectic manifolds; the identification of the real cohomology of a loop group with certain string and leading order classes; the identification of Donaldson's nu-class for 4-manifolds with a leading order class for the fibration of irreducible connections A over the quotient A/G by the gauge group.

math-ph↗
arXiv2015

Non-formal star-exponential on contracted one-sheeted hyperboloids

In this paper, we exhibit the non-formal star-exponential of the Lie group SL(2,R) realized geometrically on the curvature contraction of its one-sheeted hyperboloid orbits endowed with its natural non-formal star-product. It is done by a direct resolution of the defining equation of the star-exponential and produces an expression with Bessel functions. This yields a continuous group homomorphism from SL(2,R) into the von Neumann algebra of multipliers of the Hilbert algebra underlied by this natural star-product. As an application, we prove a new identity on Bessel functions.

math.OA↗
arXiv2014

Gauge Theories in Noncommutative Homogeneous Kähler Manifolds

We construct a gauge theory on a noncommutative homogeneous Kähler manifold, where we employ the deformation quantization with separation of variables for Kähler manifolds formulated by Karabegov. A key point in this construction is to obtaining vector fields which act as inner derivations for the deformation quantization. We show that these vector fields are the only Killing vector fields. We give an explicit construction of this gauge theory on noncommutative ${\mathbb C}P^N$ and noncommutative ${\mathbb C}H^N$.

hep-th↗
arXiv2014

The Geometry of Loop Spaces I: $H^s$-Riemannian Metrics

A Riemannian metric on a manifold M induces a family of Riemannian metrics on the loop space LM depending on a Sobolev space parameter s. We compute the connection forms of these metrics and the higher symbols of their curvature forms, which take values in pseudodifferential operators. These calculations are used in a followup paper "The Geometry of Loop Spaces II: Characteristic Classes" to construct Chern-Simons classes on the tangent bundle TLM which detect nontrivial elements in the diffeomorphism group of certain Sasakian 5-manifolds associated to Kaehler surfaces.

math.DG↗
arXiv2013

Deformation Expression for Elements of Algebras (VII) --Vacuum/Pseudo-vacuum Representations--

Thinking back the long history of physics, we see that the calculation used by physicists was nothing but the ordinary calculus. Another word, physicists have never wrote theories beyond the basic axioms of the calculus. This is not to declare of the victory of calculus or algebraic topology. On the contrary, we are thinking that every theory of mathematical physics must suggest new frontier of ordinary calculus, which are never viewed by classical geometers. Weyl algebras or Heisenberg algebras are naturally involved in slightly extended systems of the algebra of ordinary calculus, and are supported by the classical notion of phase spaces on which the general mechanics are based. The theory of deformation quantizations gives a notion of quantization of "phase space". To explain its essence in brief we proposed in the previous note the notion of $μ$-regulated algebra. In this series, we have introduced elements, called "vacuums" to consider the state vectors and the configuration spaces within the world of extended algebra of calculus with various expressions. We have found several strange elements, called polar elements, and an extended notions of vacuums, which were called pseudo-vacuums in our paper. These are not established notions in mathematical physics, but we are thinking that these must propose new frontier for mathematical physics. We are thinking that vacuums and pseudo-vacuums are not unique, but the function algebra of the configuration spaces must be an algebra similar to the Frobenius algebra defined by vacuums. The point in this note is that to obtain classical pictures one has often to restrict the expression parameters, and there are two essentially different expression parameters.

math-ph↗
arXiv2012

Secondary Characteristic Classes on Loop Spaces

A Riemannian metric on a manifold M induces a family of Riemannian metrics on the loop space LM depending on a Sobolev space parameter s. The connection and curvature forms of these metrics take values in pseudodifferential operators. We develop a theory of Wodzicki-Chern-Simons classes using the s=0, 1 connections and the Wodzicki residue. These classes distinguish the smooth homotopy type of some circle actions on M = S^2 x S^3, and imply that the fundamental group of Diff(M) is infinite.

math.DG↗
arXiv2012

Deformation Expression for Elements of Algebras (II) --(Weyl algebra of 2m-generators)--

This is a noncommutative version of the previous work entitled "Deformation Expression for Elements of Algebras (I)." In general in a noncommutative algebra, there is no canonical way to express elements in univalent way, which is often called "ordering problem". In this note we discuss this problem in the case of the Weyl algebra of 2m-generators. By fixing an expression, we extends Weyl algebra transcendentally. We treat *-exponential functions of linear forms, and quadratic forms of crossed symbol under generic expression parameters.

math-ph↗