Results 1  10
of
134
Symplectic reflection algebras, CalogeroMoser space, and deformed HarishChandra homomorphism
 Invent. Math
"... To any finite group Γ ⊂ Sp(V) of automorphisms of a symplectic vector space V we associate a new multiparameter deformation, Hκ, of the algebra C[V]#Γ, smash product of Γ with the polynomial algebra on V. The parameter κ runs over points of CP r, where r = number of conjugacy classes of symplectic ..."
Abstract

Cited by 179 (36 self)
 Add to MetaCart
To any finite group Γ ⊂ Sp(V) of automorphisms of a symplectic vector space V we associate a new multiparameter deformation, Hκ, of the algebra C[V]#Γ, smash product of Γ with the polynomial algebra on V. The parameter κ runs over points of CP r, where r = number of conjugacy classes of symplectic reflections in Γ. The algebra Hκ, called a symplectic reflection algebra, is expected to be related to the coordinate ring of a universal Poisson deformation of the quotient singularity V/Γ. If Γ is the Weyl group of a root system in a vector space h and V = h ⊕ h ∗ , then the algebras Hκ are certain ‘rational ’ degenerations of the double affine Hecke algebra introduced earlier by Cherednik. Let Γ = Sn, the Weyl group of g = gl n. We construct a 1parameter deformation of the HarishChandra homomorphism from D(g) g, the algebra of invariant polynomial differential operators on the Lie algebra g = gl n, to the algebra of Sninvariant differential operators on the Cartan subalgebra C n with rational coefficients. The second order Laplacian on g goes, under our deformed homomorphism, to the CalogeroMoser
Hopf algebras, cyclic cohomology and the transverse index theorem
 Comm. Math. Phys
, 1998
"... In this paper we present the solution of a longstanding internal problem of noncommutative geometry, namely the computation of the index of transversally elliptic operators on foliations. ..."
Abstract

Cited by 142 (18 self)
 Add to MetaCart
In this paper we present the solution of a longstanding internal problem of noncommutative geometry, namely the computation of the index of transversally elliptic operators on foliations.
From subfactors to categories and topology I. Frobenius algebras in and Morita equivalence of tensor categories
 J. Pure Appl. Alg
, 2003
"... We consider certain categorical structures that are implicit in subfactor theory. Making the connection between subfactor theory (at finite index) and category theory explicit sheds light on both subjects. Furthermore, it allows various generalizations of these structures, e.g. to arbitrary ground f ..."
Abstract

Cited by 52 (6 self)
 Add to MetaCart
We consider certain categorical structures that are implicit in subfactor theory. Making the connection between subfactor theory (at finite index) and category theory explicit sheds light on both subjects. Furthermore, it allows various generalizations of these structures, e.g. to arbitrary ground fields, and the proof of new results about topological invariants in three dimensions. The central notion is that of a Frobenius algebra in a tensor category A, which reduces to the classical notion if A = FVect, where F is a field. An object X ∈ A with twosided dual X gives rise to a Frobenius algebra in A, and under weak additional conditions we prove a converse: There exists a bicategory E with ObjE = {A, B} such that EndE(A) ⊗ ≃ A and such that there are J, J: B ⇋ A producing the given Frobenius algebra. Many properties (additivity, sphericity, semisimplicity,...) of A carry over to the bicategory E. We define weak monoidal Morita equivalence of tensor categories, denoted A ≈ B, and establish a correspondence between Frobenius algebras in A and tensor categories B ≈ A. While considerably weaker than equivalence of tensor categories, weak monoidal Morita equivalence A ≈ B has remarkable consequences: A and B have equivalent (as braided tensor categories) quantum doubles (‘centers’) and (if A, B are semisimple spherical or ∗categories) have equal dimensions and give rise the same state sum invariant of closed oriented 3manifolds as recently defined by Barrett and Westbury. An instructive example is provided by finite dimensional semisimple and cosemisimple Hopf algebras, for which we prove H − mod ≈ ˆH − mod. The present formalism permits a fairly complete analysis of the center of a semisimple spherical category, which is the subject of the companion paper math.CT/0111205. 1
Noncommutative geometry, quantum fields and motives
 Colloquium Publications, Vol.55, American Mathematical Society
, 2008
"... ..."
Ultraviolet Finite Quantum Field Theory on Quantum
 Spacetime, Comm. Math. Phys
"... Dedicated to Rudolf Haag on the occasion of his 80 th birthday. We discuss a formulation of quantum field theory on quantum space time where the perturbation expansion of the Smatrix is term by term ultraviolet finite. The characteristic feature of our approach is a quantum version of the Wick prod ..."
Abstract

Cited by 31 (7 self)
 Add to MetaCart
Dedicated to Rudolf Haag on the occasion of his 80 th birthday. We discuss a formulation of quantum field theory on quantum space time where the perturbation expansion of the Smatrix is term by term ultraviolet finite. The characteristic feature of our approach is a quantum version of the Wick product at coinciding points: the differences of coordinates qj − qk are not set equal to zero, which would violate the commutation relation between their components. We show that the optimal degree of approximate coincidence can be defined by the evaluation of a conditional expectation which replaces each function of qj − qk by its expectation value in opti(q1 + · · ·+qn) mally localized states, while leaving the mean coordinates 1 n invariant. The resulting procedure is to a large extent unique, and is invariant under translations and rotations, but violates Lorentz invariance. Indeed, optimal localization refers to a specific Lorentz frame, where the electric and magnetic parts of the commutator of the coordinates have to coincide [11]. Employing an adiabatic switching, we show that the Smatrix is term by term finite. The matrix elements of the transfer matrix are determined, at each order in the perturbative expansion, by kernels with Gaussian decay in the Planck scale. The adiabatic limit and the large scale limit of this theory will be studied elsewhere. 1
Inclusions of von Neumann Algebras, and Quantum Groupoïds II
"... In a former article, in collaboration with JeanMichel Vallin, we have constructed two "quantum groupods" dual to each other, from a depth 2 inclusion of von Neumann algebras M0 M1 . We are now investigating in greater details these structures : in the previous article, we had constructed the anal ..."
Abstract

Cited by 28 (7 self)
 Add to MetaCart
In a former article, in collaboration with JeanMichel Vallin, we have constructed two "quantum groupods" dual to each other, from a depth 2 inclusion of von Neumann algebras M0 M1 . We are now investigating in greater details these structures : in the previous article, we had constructed the analog of a coproduct, and in this paper, are de ned a coinverse, by making the polar decomposition of the analog of the antipode, and left and right invariant Haar operatorvalued weights. These two structures of "quantum groupod", dual to each other, can be put on the relative commutants M 1 \M3 , in such a way that the canonical Jones' tower associated to the inclusion can be described as a tower of successive crossedproducts by these two structures. Date: november 99. 1.
The Apolynomial from the noncommutative viewpoint
 Trans. Amer. Math. Soc
"... This paper places the Apolynomial of a knot into the framework of noncommutative geometry. The Apolynomial was introduced in [CCGLS]. The Apolynomial describes how the Sl2Ccharacters of a knot lie inside the Sl2Ccharacters of its boundary torus. It is known ..."
Abstract

Cited by 22 (3 self)
 Add to MetaCart
This paper places the Apolynomial of a knot into the framework of noncommutative geometry. The Apolynomial was introduced in [CCGLS]. The Apolynomial describes how the Sl2Ccharacters of a knot lie inside the Sl2Ccharacters of its boundary torus. It is known
The String Uncertainty Relations follow from the New Relativity Principle
, 2000
"... The String Uncertainty Relations have been known for some time as the stringy corrections to the original Heisenberg’s Uncertainty principle. In this letter the Stringy Uncertainty relations, and corrections thereof, are explicitly derived from the New Relativity Principle that treats all dimensions ..."
Abstract

Cited by 19 (11 self)
 Add to MetaCart
The String Uncertainty Relations have been known for some time as the stringy corrections to the original Heisenberg’s Uncertainty principle. In this letter the Stringy Uncertainty relations, and corrections thereof, are explicitly derived from the New Relativity Principle that treats all dimensions and signatures on the same footing and which is based on the postulate that the Planck scale is the minimal length in Nature in the same vein that the speed of light was taken as the maximum velocity in Einstein’s theory of Special Relativity. The Regge behaviour of the string’s spectrum is also a natural consequence of this New Relativity Principle. Recently we have proposed that a New Relativity principle may be operating in Nature which could reveal important clues to find the origins of M theory [1]. We were forced to introduce this new Relativity principle, where all dimensions and signatures of spacetime are on the same footing, to find a fully covariant formulation of the pbrane Quantum Mechanical Loop Wave equations. This New Relativity Principle, or the principle of Polydimensional Covariance as has been called by Pezzaglia, has also been crucial in the derivation of Papapetrou’s equations of motion of a spinning particle in curved spaces that was a long standing problem which lasted almost 50 years [2]. A Clifford calculus was used where all the equations
Spectral Asymmetry, Zeta Functions and the Noncommutative Residue
"... Abstract. In this paper, motivated by an approach developed by Wodzicki, we look at the spectral asymmetry of elliptic ΨDO’s in terms of theirs zeta functions. First, using asymmetry formulas of Wodzicki we study the spectral asymmetry of odd elliptic ΨDO’s and of geometric Dirac operators. In parti ..."
Abstract

Cited by 18 (7 self)
 Add to MetaCart
Abstract. In this paper, motivated by an approach developed by Wodzicki, we look at the spectral asymmetry of elliptic ΨDO’s in terms of theirs zeta functions. First, using asymmetry formulas of Wodzicki we study the spectral asymmetry of odd elliptic ΨDO’s and of geometric Dirac operators. In particular, we show that the eta function of a selfadjoint elliptic odd ΨDO is regular at every integer point when the dimension and the order have opposite parities (this generalizes a well known result of BransonGilkey for Dirac operators), and we relate the spectral asymmetry of a Dirac operator on a Clifford bundle to the Riemmanian geometric data, which yields a new spectral interpretation of the Einstein action from gravity. We also obtain a large class of examples of elliptic ΨDO’s for which the regular values at the origin of the (local) zeta functions can easily be seen to be independent of the spectral cut. On the other hand, we simplify the proofs of two wellknown and difficult results of Wodzicki: (i) The independence with respect to the spectral cut of the regular value at the origin of the zeta function of an elliptic ΨDO; (ii) The vanishing of the noncommutative residue of a zero’th order ΨDO projector. These results were proved by Wodzicki using a quite difficult and involved characterization of local invariants of spectral asymmetry, which we can bypass here. Finally, in an appendix we give a new proof of the aforementioned asymmetry formulas of Wodzicki. 1.