Home page of the Trieste unit of the Research Program: 
Singularities, Integrability, Symmetries 
(Scientific Coordinator: Francesco Calogero - Universita' La Sapienza - Roma)


Local Research Unit:
Symmetries, singularities and integrability problems in noncommutative geometry 
Scientific Coordinator of Research Unit
Ludwik Dabrowski

Location of the Research Unit
SISSA - Trieste 

Scientific Sectors interested in the Research
FIS/02, MAT/07  

Key Words


Human Resources
University Personnel of the Research Unit
N. Name
1 Dabrowski, Ludwik
2 Reina, Cesare
Personnel from other Universities
N. Name
1 Landi, Giovanni
N. Name
1 Hawkins, Eli
2 Loutsenko, Igor
3 Perrot, Denis
PhD students
N. Name
1 Correggi, Michele
2 Mossa, Alessandro
3 Pagani, Chiara
4 Panati, Gianluca
5 Parodi, Adriano
6 Perroni, Fabio

Scientific Background
The study of noncommutative geometry fits in a natural manner into the framework of the research project "Singularities, Integrability and Symmetries"; in fact it yields some methods to analyze singularities, symmetries and integrability properties and study them in a wider context, both in the strict geometric sense and from the point of view of applications to quantum field theory, strings and solvable models in statistical field theory.
For example, it is a suitable tool to study the quotient spaces of singular foliations [C]. To such spaces one can associate some noncommutative algebras which are analogues of the algebras of functions on the usual spaces. The most known example is the noncommutative torus [CR] which is associated to the space S^1/tZ, i.e. the quotient of S^1 by the equivalence relation which identifies the points on the orbits of irrational rotations x-> x + t mod 1, on S^1.
Moreover the study of the quantum completely integrable systems leads in a natural manner to a generalization of usual symmetries known as quantum groups (cf. [FRT] and the references therein). Quantum groups specify also the "braiding" (statistics) of tensor products of two or more identical quantum systems cf. [M.S] and can link spin and statistics [O].
A large class of models in noncommutative geometry originates in the framework of deformation quantization (*-products) [K] of the Poisson structures. Classical integrable systems are often characterized by the presence of symmetries related to Lie-Poisson groups (which can be viewed as the semiclassical limit of quantum groups) and/or the presence of bi-Hamiltonian structures described via pencils of Poisson structures [M.F].
Noncommutative geometry is of great interest also in other areas, among which one can mention models of space-time at short distances, the unification of fundamental interactions and the regularization of ultraviolet divergences in quantum field theory and string theory.
However till now only field theories on very special spaces have been proposed and it is evident that more interesting examples are needed together with field configurations on them. The most studied example is given by Yang-Mills theory on noncommutative tori mentioned above, which has been recently used in string theory [CDS, SW]. On such tori also nonlinear sigma models [DKL] have been considered. Recently some examples corresponding to instantons on spheres, in particular in four dimensions, have been constructed [CL,DLM,BCT,S,BG,DL,HS,V,LM,CD-V,AB].
In general, the symmetry aspects of Yang-Mills theories (for instance the orbits of gauge transformations) are classically studied by means of connections on principal fibre bundles. Quantum principal fibre bundles are best described as (Hopf-)Galois extensions while (spaces of sections of) vector bundles appear as modules associated to the representations of quantum groups. In this framework also covariant derivatives and principal connections have been studied [BM, HM, DGH].


[AB] P. Aschieri, F. Bonechi. On the Noncommutative Geometry of Twisted Spheres (math.QA/0108136) Lett. Math. Phys. in stampa
[BCT] F. Bonechi, N. Ciccoli, M. Tarlini. Noncommutative Instantons on the 4-Sphere from Quantum Groups. (math.QA/0012236)
[BG] T. Brzezinski and C. Gonera. Non-commutative 4-spheres based on all Podles 2-spheres and beyond. (math.QA/0101129)
[BM] T. Brzezinski, S. Majid. Quantu m Group Gauge Theory on Quantum Spaces. Commun. Math. Phys. 157 (1993) 591--638.
[C] A. Connes. Noncommutative geometry. Academic Press 1994.
[CDS] A. Connes, M. Douglas and A. Schwarz. Noncommutative geometry and Matrix theory: compactification on tori. JHEP 2 (1998) 3
[CD-V] A. Connes, M. Dubois-Violette. Noncommutative finite-dimensional manifolds. I. Spherical manifolds and related examples. (math.QA/0107070)
[CL] A. Connes, G. Landi. Noncommutative manifolds, the instanton algebra and isospectral deformations. (math.QA/0011194)
[CR] A. Connes, M. Rieffel. Yang-Mills for Non-commutative Two-Tori. Contemp. Math. 62 (1987) 237-266
[DGH] L. Dabrowski, H. Grosse, P.M. Hajac. Strong Connections and Chern-Connes Pairing in the Hopf-Galois Theory. Commun. Math. Physics 220 (2001) 301-331
[DKL] L. Dabrowski, T. Krajewski, G. Landi. Some Properties of Non-linear sigma Models in Noncommutative Geometry. Int. J. Mod. Phys. B14 (2000) 2367-2382
[DL] L. Dabrowski, G. Landi. Instanton algebras and quantum 4-spheres. (math.QA/0101177) Differ. Geom. Appl. 16 (2002) 277-284
[DLM] L. Dabrowski, G. Landi, T. Masuda. Instantons on the Quantum $4$-Spheres $S^4_q$. Commun. Math. Phys. 221 (2001) 161-168.
[FRT] L. D. Faddeev, N. Y. Reshetikhin, L. A. Takhtajan. Quantization Of Lie Groups And Lie Algebras. Lengingrad Math. J. 1 (1990) 193 [Alg. Anal. 1 (1990) 178].
[HM] P. Hajac, S. Majid. Projective module description of the q-monopole. Commun. Math. Phys. 206 (1999) 247
[HS] J.H. Hong, W. Szymanski. Quantum spheres and projective spaces as graph algebras. University of Newcastle Preprint, January 2001
[K] M. Kontsevich. Deformation quantization of Poisson manifolds, I. (q-alg/9709040)
[LM] G. Landi, J. Madore. Twisted Configurations over Quantum Euclidean Spheres. (math.QA/0102195)
[M.F] F. Magri. A simple model of the integrable Hamiltonian equation. J. Math. Phys. vol. 19, (1978) 1156
[M.S] S. Majid. Foundations of Quantum Group Theory. Cambridge Univ. Press 1995.
[O] R. Oeckl. The Quantum Geometry of Supersymmetry and the Generalized Group Extension Problem. (hep-th/0106122)
[S] A. Sitarz. More noncommutative 4-spheres. (math-ph/0101001)
[SW] N. Seiberg, E. Witten. String Theory and Noncommutative Geometry. JHEP 09 (1999) 32
[V] J.C. Varilly. Quantum symmetry groups of noncommutative spheres. (math.QA/0102065)

Research Program Description
The Trieste group will work on classical integrable systems equipped with the bi-Hamiltonian structure, in the framework of deformation quantization (*-products). Families of deformations induced by the pencils of Poisson structures, the resulting algebras and their representations will be studied. In particular we plan to investigate the Heisenberg evolution equations, the semiclassical limit and the existence of Lax pairs with parameter for the integrable system. On this point a collaboration is expected with other units involved in the project which are active on analogous topics (e.g. Roma, Napoli).
A substantial part of the activity of the local unit will be devoted to the construction of gauge theories on noncommutative spaces previously mentioned, and in particular on so called Connes-Landi spheres, which possess the structure of noncommutative spin manifold. We intend to construct gauge fields (connections) on the projective modules of instantonic type, study them as solutions of suitable field equations, including the selfduality conditions, and calculate the corresponding generalized topological charges (in collaboration with the Napoli unit). On more general kind of quantum spheres the existence and the properties of a suitable Dirac operator, the space of connections, the action of the group of gauge transfromations and the corresponding orbit space will be analysed. Also the theory of nonlinear sigma models introduced by some of us on noncommutative tori and on more general quantum spaces will be developed.
A related argument will be the study, from the point of view of spin-statistics relation, of the quantum principal fibre bundle F --> SLq(2) --> SL(2) (where q is a root of unity) which describes a quantum covering of the Spin group in dimension 3.


[1] Bonora, C. Reina, A. Zampa. Enhanced gauge symmetries on elliptic K3. Phys. Lett. B 452 (1999) 244-250
[2] L. Castellani, G. Landi, F. Lizzi (Editors). Noncommutative Geometry and Hopf Algebras in Field Theory and Particle Physics. World Scientific, Singapore, 2000
[3] A. Connes e G. Landi. Noncommutative Manifolds, the Instanton algebra and isospectral deformations. Commun. Math. Phys. 221 (2001) 141-159.
[4] L. Dabrowski, P.M. Hajac e P. Siniscalco. Explicit Hopf-Galois Description of Induced Frobenius Homomorphisms, in: "Quantum Groups, Noncommutative Geometry and Fundamental Physical Interactions", D. Kastler et al. (Nova Science Publisher, Commack NY, 1999
[5] L. Dabrowski, T. Krajewski, G. Landi. Some Properties of Non-linear sigma Models in Noncommutative Geometry. Int. J. Mod. Phys. B14 (2000) 2367-2382
[6] L. Dabrowski, H. Grosse, P.M. Hajac. Strong Connections and Chern-Connes Pairing in the Hopf-Galois Theory.
Commun. Math. Physics 220 (2001) 301-331.
[7] L. Dabrowski, G. Landi. Instanton Algebras and Quantum 4-Spheres. math.QA/0101177; Diff. Geom. Appl. in stampa.
[8] L. Dabrowski, G. Landi, T. Masuda. Instantons on the Quantum 4-Spheres, Commun. Math. Phys. 221 (2001) 161-168.
[9] L. Dabrowski, C. Reina, A. Zampa. A[Slq(2)] at roots of unity is a free module over A[Sl(2)]. Lett. Math. Phys. 52 (2000) 339-342.
[10] G. Dell'Antonio, G. Panati. Zero-energy resonances and the flux-across-surfaces theorem, math-ph/0110034.
[11] E. Ercolessi, G. Landi, P. Teotonio-Sobrinho. K-theory of Noncommutative Lattices. K-Theory 18 (1999) 339-362
[12] D. Fabbri, P. Fre, L. Gualtieri, C. Reina, A. Tomasiello, A. Zaffaroni, A. Zampa. 3D superconformal theories from Sasakian seven-manifolds: a new nontrivial evidence for AdS_4/CFT_3. Nucl.Phys. B577 (2000) 547-608
[13] G. Falqui, C. Reina, A. Zampa. Super KP equations and Darboux transformations: another perspective on the Jacobian Super KP hirearchy. J. Geom. Phys. 35 (2000) 239-272
[14] G. Falqui, C. Reina, A. Zampa. A note on the super Krichever map. J. Geom. Phys. 37 (2001) 169
[15] Eli Hawkins. Geometric Quantization of Vector Bundles. Commun.Math.Phys. 215 (2000) 409-432
[16] Eli Hawkins. Quantization of Equivariant Vector Bundles. Commun.Math.Phys. 202 (1999) 517-546
[17] G. Landi. An Introduction to Noncommutative Spaces and Their Geometries. Lecture Notes in Physics, m51 Springer-Verlag, Berlin-Heidelberg, 1997
[18] G. Landi. Eigenvalues as Dynamical Variables. Quaderno Dipartimento di Scienze Matematiche, Trieste, DSMA-TS 450, 1999. (gr-qc/9906044).
[19] G. Landi. Noncommutative Geometry (An Introduction to Selected Topics). Quaderno Dipartimento di Scienze Matematiche, Trieste, DSMA-TS 488, marzo 2001. Special issue of `Acta Applicandae Mathematicae', in stampa.
[20] G. Landi. Deconstructing (Super)-Monopoles. Seminari di Geometria 1999-2000, Dipartimento di Matematica, Universita` di Bologna, in stampa.
[21] G. Landi. Deconstructing Monopoles and Instantons. Rev. Math. Phys. 12 (2000) 1367-1390
[22] G. Landi. Projective Modules of Finite Type over the Supersphere S^{2,2} Diff. Geom. Appl. 14 (2001) 95-111.
[23] G. Landi. Projective Modules of Finite Type and Monopoles over S^2, J. Geom. Phys. 37 (2001) 47-62
[24] G. Landi, F. Lizzi. Projective Systems of Noncommutative Lattices as a Pregeometric Substratum, in: "Quantum Groups, Noncommutative Geometry and Fundamental Physical Interactions", D. Kastler et al. (Nova Science Publisher, Commack NY, 1999), pp. 85-113.
[25] G. Landi, F. Lizzi, R. Szabo. String Geometry and the Noncommutative Torus. Commun. Math. Phys. 206 (1999) 603-637
[26] G. Landi, F. Lizzi, R.J. Szabo. From Large N Matrices to the Noncommutative Torus, Commun. Math. Phys. 217 (2001) 181-201
[27] G. Landi, J. Madore. Twisted Configurations over Quantum Euclidean Spheres. math.QA/0102195.
[28] G. Panati, H. Spohn, S. Teufel. Space-Adiabatic Perturbation Theory. (math-ph/0201055)
[29] G. Panati, H. Spohn, S. Teufel. Space-adiabatic Decoupling to All Orders. (quant-ph/0201123)
[30] Panati G., Teta A. The flux-across-surfaces theorem for a point interaction hamiltonian. In: Gesztesy, F., Holden H., Jost J., Paycha S., Rockner M., Scarlatti, S. (Eds.) Stochastic Processes, Physics and Geometry: New Interplays. American Mathematical Society Providence, 1999 Rhode Island, 431-442
[31] D. Perrot. BRS Cohomology And The Chern Character In Non-Commutative Geometry. Lett.Math.Phys. 50 (1999) 135-144
[32] D. Perrot. On the Topological Interpretation of Gravitational Anomalies. (math-ph/0006003), Commun. Math. Phys., in press
[33] D. Perrot. A Riemann-Roch Theorem For One-Dimensional Complex Groupoids. (math-ph/0001040), J. Geom. Phys., in press

Last updated: 19/12/2002 by F. Musso