arXiv subjects

Gilles Halbout

Publications and source records attributed to Gilles Halbout.

13 recordsLinked to original sources

arXiv2017

Tressages des groupe de Poisson formels à dual quasitriangulaire

Let $ \mathfrak{g} $ be a quasitriangular Lie bialgebra over a field $ K $ of characteristic zero, and let $ \mathfrak{g}^* $ be its dual Lie bialgebra. We prove that the formal Poisson group $ K\big[\big[\mathfrak{g}^*\big]\big] $ is a braided Hopf algebra, thus generalizing a result due to Reshetikhin (in the case $ \, \mathfrak{g} = \mathfrak{sl}(2,K) \, $). The proof is via quantum groups, using the existence of a quasitriangular quantization of $ \mathfrak{g}^* $, as well as the fact that this one provides also a quantization of $ K\big[\big[\mathfrak{g}^*\big]\big] \, $.

math.QA↗

arXiv2011

Weak quantization of Poisson structures

In this paper we prove that any Poisson structure on a sheaf of Lie algebroids admits a weak deformation quantization, and give a sufficient condition for such a Poisson structure to admit an actual deformation quantization. We also answer the corresponding classification problems. In the complex symplectic case, we recover in particular some results of Nest-Tsygan and Polesello-Schapira. We begin the paper with a recollection of known facts about deformation theory of cosimplicial differential graded Lie algebras.

math.QA↗

arXiv2010

Dunkl operator and quantization of $\mathbb{Z}_2$-singularity

Let $(X,ω)$ be a symplectic orbifold which is locally like the quotient of a $\mathbb{Z}_2$ action on $\reals^n$. Let $A^{((\hbar))}_X$ be a deformation quantization of $X$ constructed via the standard Fedosov method with characteristic class being $ω$. In this paper, we construct a universal deformation of the algebra $A^{((\hbar))}_X$ parametrized by codimension 2 components of the associated inertia orbifold $\widetilde{X}$. This partially confirms a conjecture of Dolgushev and Etingof in the case of $\mathbb{Z}_2$ orbifolds. To do so, we generalize the interpretation of Moyal star-product as a composition of symbol of pseudodifferential operators in the case where partial derivatives are replaced with Dunkl operators. The star-products we obtain can be seen as globalizations of symplectic reflection algebras.

math.QA↗

arXiv2009

Noncommutative Poisson structures on Orbifolds

In this paper, we compute the Gerstenhaber bracket on the Hoch-schild cohomology of $C^\infty(M)\rtimes G$ for a finite group $G$ acting on a compact manifold $M$. Using this computation, we obtain geometric descriptions for all noncommutative Poisson structures on $C^\infty(M)\rtimes G$ when $M$ is a symplectic manifold. We also discuss examples of deformation quantizations of these noncommutative Poisson structures.

math.QA↗

arXiv2008

Deformations of linear Poisson orbifolds

Let $Γ$ be a finite group acting faithfully and linearly on a vector space $V$. Let $T(V)$ ($S(V)$) be the tensor (symmetric) algebra associated to $V$ which has a natural $Γ$ action. We study generalized quadratic relations on the tensor algebra $T(V)\rtimes Γ$. We prove that the quotient algebras of $T(V)\rtimes Γ$ by such relations satisfy PBW property. Such quotient algebras can be viewed as quantizations of linear or constant Poisson structures on $S(V)\rtimes Γ$, and are natural generalizations of symplectic reflection algebras.

math.QA↗

arXiv2008

Quantization of $r-Z$-quasi-Poisson manifolds and related modified classical dynamical $r$-matrices

Le $X$ be a $C^\infty$-manifold and $\g$ be a finite dimensional Lie algebra acting freely on $X$. Let $r \in \ve^2(\g)$ be such that $Z=[r,r] \in \ve^3(\g)^\g$. In this paper we prove that every quasi-Poisson $(\g,Z)$-manifold can be quantized. This is a generalization of the existence of a twist quantization of coboundary Lie bialgebras (\cite{EH}) in the case $X=G$ (where $G$ is the simply connected Lie group corresponding to $\g$). We deduce our result from a generalized formality theorem. In the case Z=0, we get a new proof of the existence of (equivariant) formality theorem and so (equivariant) quantization of Poisson manifold ({\it cf.} \cite{Ko,Do}). As a consequence of our results, we get quantization of modified classical dynamical $r$-matrices over abelian bases in the reductive case

math.QA↗

arXiv2007

Quantization of Poisson-Hopf stacks associated with group Lie bialgebras

Let $G$ be a Poisson Lie group and $\g$ its Lie bialgebra. Suppose that $\g$ is a group Lie bialgebra. This means that there is an action of a discrete group $Γ$ on $G$ deforming the Poisson structure into coboundary equivalent ones. Starting from this we construct a non-trivial stack of Hopf-Poisson algebras and prove the existence of associated deformation quantizations. This non-trivial stack is a stack of functions on the formal Poisson group, dual of the starting $Γ$ Poisson-Lie group. To quantize this non-trivial stack we use quantization of a $Γ$ Lie bialgebra which is the infinitesimal of a $Γ$ Poisson-Lie group (cf \cite{MS} for simple Lie groups and $Γ$ a covering of the Weyl group and \cite{EH} for quantization in the general case).

math.QA↗

arXiv2006

Formality theorems for Hochschild chains in the Lie algebroid setting

In this paper we prove Lie algebroid versions of Tsygan's formality conjecture for Hochschild chains both in the smooth and holomorphic settings. In the holomorphic setting our result implies a version of Tsygan's formality conjecture for Hochschild chains of the structure sheaf of any complex manifold and in the smooth setting this result allows us to describe quantum traces for an arbitrary Poisson Lie algebroid. The proofs are based on the use of Kontsevich's quasi-isomorphism for Hochschild cochains of R[[y_1,...,y_d]], Shoikhet's quasi-isomorphism for Hochschild chains of R[[y_1,...,y_d]], and Fedosov's resolutions of the natural analogues of Hochschild (co)chain complexes associated with a Lie algebroid.

math.KT↗

arXiv2005

Lift of $C\_\infty$ and $L\_\infty$ morphisms to $G\_\infty$ morphisms

Let $\g\_2$ be the Hochschild complex of cochains on $C^\infty(\RM^n)$ and $\g\_1$ be the space of multivector fields on $\RM^n$. In this paper we prove that given any $G\_\infty$-structure ({\rm i.e.} Gerstenhaber algebra up to homotopy structure) on $\g\_2$, and any $C\_\infty$-morphism $ϕ$ ({\rm i.e.} morphism of commutative, associative algebra up to homotopy) between $\g\_1$ and $\g\_2$, there exists a $G\_\infty$-morphism $Φ$ between $\g\_1$ and $\g\_2$ that restricts to $ϕ$. We also show that any $L\_\infty$-morphism ({\rm i.e.} morphism of Lie algebra up to homotopy), in particular the one constructed by Kontsevich, can be deformed into a $G\_\infty$-morphism, using Tamarkin's method for any $G\_\infty$-structure on $\g\_2$. We also show that any two of such $G\_\infty$-morphisms are homotopic.

math.QA↗

arXiv2005

Formality theorem for Lie bialgebras and quantization of coboundary r-matrices

Let $(g,δ_\hbar)$ be a Lie bialgebra. Let $(U_\hbar(g),Δ_\hbar)$ a quantization of $(g,δ_\hbar)$ through Etingof-Kazhdan functor. We prove the existence of a $L_\infty$-morphism between the Lie algebra $C(\g)=Λ(g)$ and the tensor algebra $TU=T(U_\hbar(g)[-1])$ with Lie algebra structure given by the Gerstenhaber bracket. When $(g,δ_\hbar,r)$ is a coboundary Lie bialgebra, we deduce from the formality morphism the existence of a quantization $R$ of $r$.

math.QA↗

arXiv2005

Formalite $G_\infty$ adaptee et star-representations sur des sous-varietes coisotropes

Let X be a Poisson manifold and C a coisotropic submanifold and let I be the vanishing ideal of C. In this work we want to construct a star product * on X such that I[[lambda]] is a left ideal for *. Thus we obtain a representation of the star product algebra A[[lambda]] = C^\infty(X)[[lambda]] on B[[lambda]] = A[[lambda]] / I[[lambda]] deforming the usual representation of A on the functions on C. The result follows from a generalization of Tamarkin's formality adapted to the submanifold C. We show that in the case X = R^n and C = R^{n-l} with l > 1 there are no obstructions to this formality.

math.QA↗

arXiv2002

Braiding structures on formal Poisson groups and classical solutions of the QYBE

If g is a quasitriangular Lie bialgebra, one can asks what is the geometrical meaning of its r-matrix. A first answer was given in a paper by Weinstein and Xu, using purely geometrical means: roughly, one has that the formal Poisson group F[[g^*]] is endowed with a "braiding", i.e. a distinguished operator on its tensor square which satisfy quasitriangularity conditions (in particular, it is a solution of the QYBE). Independently, the authors also found, by means of quantum groups, that F[[g^*]] has a braiding. In this paper we compare these two approaches and their outcomes. First, we show that the two braidings obtained in the two processes do share several similar properties (in particular, the construction is functorial). Second, in the simplest case (G = SL_2) we prove that the two braidings do coincide. The question then rises of whether they are always the same: this problem is addressed and solved in math.QA/0207235, in a much broader context, in which unicity of braidings is proved.

math.QA↗

arXiv1999

Braidings of Poisson groups with quasitriangular dual (Tressages des groupes de Poisson à dual quasitriangulaire)

Let g be a quasitriangular Lie bialgebra over a field k of characteristic zero, and let g^* be its dual Lie bialgebra. We prove that the formal Poisson group F[[g^*]] is a braided Hopf algebra. More generally, we prove that if (U_h,R) is any quasitriangular QUEA, then (U_h', Ad(R)|_{U_h' \otimes U_h'}) --- where U_h' is defined by Drinfeld --- is a braided QFSHA. The first result is then just a consequence of the existence of a quasitriangular quantization (U_h,R) of U(g) and of the fact that U_h' is a quantization of F[[g^*]]. ----- Soit g une bigèbre de Lie quasitriangulaire sur un corps k de characteristique zero, et soit g^* sa bigèbre de Lie duale. Nous prouvons que le groupe de Poisson formel F[[g^*]] est une algebre de Hopf tressée. Plus en général, nous prouvons que, si (U_h,R) est une QUEA quasitriangulaire, alors (U_h', Ad(R)|_{U_h' \otimes U_h'}) --- où U_h' est definie par Drinfeld --- est une QFSHA tressée. Le premier résultat est alors une consequence de l'existence d'une quantification quasitriangulaire (U_h,R) de U(g) et du fait que U_h' est une quantification de F[[g^*]].

math.QA↗