Noncommutative Field Theory
subject: THEORIE QUANTIQUE DES CHAMPS
subject: ESPACE-TEMPS
subject: CINEMATIQUE
subject: MODELES DES CORDES VIBRANTES
subject: SOLITONS
subject: INSTANTONS
description: Abstract : We review the generalization of field theory to space-time with noncommuting coordinates, starting with the basics and covering most of the active directions of research. Such theories are now known to emerge from limits of M theory and string theory, and to describe quantum Hall states. In the last few years they have been studied intensively, and many qualitatively new phenomena have been discovered, both on the classical and quantum level. To appear in Reviews of Modern Physics.
creator: NEKRASOV
creator: DOUGLAS
source: P/01/27
publisher: IHES
date: 06/2001
format: A4
format: 31 f.
language: EN
type: TEXTE
type: PREPUBLICATION
coverage: 2001

Milne Universe, Tachyons, and quantum group
subject: MILNE
subject: TACHYONS
subject: THEORIE QUANTIQUE DES CHAMPS
description: Abstract : We analyze the spectrum of the bosonic and superstring on the orbifold of the space-time by a boost, leading to the cosmological singularity. We show that the modular invariance leads to the spectrum where the twisted sector tachyon, together with all other twisted sector fields, present in the Euclidean version of the orbifold, is absent. This makes impossible to resolve the singularity by a marginal deformation of the worldsheet CFT. We also establish a relation between the resolution of rotational orbifolds in Euclidean and Lorentzian setups, and quantum groups. The analysis confirms the impossibility of resolving the cosmological orbifold singularity.
creator: NEKRASOV
source: P/02/13
publisher: IHES
date: 03/2002
format: A4
format: 9 f.
language: EN
type: TEXTE
type: PREPUBLICATION
coverage: 2002

Lectures on open strings, and noncommutative Gauge theories
subject: CHAMPS DE JAUGE
subject: PHYSIQUE
subject: MODELES DES CORDES VIBRANTES
description: Abstract :The background independent formulation of the gauge theories on D-branes in flat space-time is considered, some examples of the solutions of their equations of motion are presented, the solutions of Dirac equation in these backgrounds are analyzed, and the generalizations to the curved spaces, like orbifolds, conifolds, and K3 surfaces are discussed.
creator: NEKRASOV
source: P/02/14
publisher: IHES
date: 03/2002
format: A4
format: 8 f.
language: EN
type: TEXTE
type: PREPUBLICATION
coverage: 2002

Trieste lectures on solitons in noncommutative Gauge theories
subject: CHAMPS DE JAUGE
subject: PHYSIQUE
subject: SOLITONS
description: Abstract : We present a pedagogical introduction into noncommutative gauge theories, their stringy origin, and non-perturbative effects, including monopole and instanton solutions.
creator: NEKRASOV
source: P/02/18
publisher: IHES
date: 03/2002
format: A4
format: 34 f.
language: EN
type: TEXTE
type: PREPUBLICATION
coverage: 2002

Noncommutative instantons revisited
subject: INSTANTONS
subject: CHAMPS DE JAUGE
subject: PHYSIQUE
description: Abstract : We find a new gauge in which U(1) noncommutative instantons are explicitly non-singular on noncommutative R^4. We also present a pedagogical introduction to the noncommutative gauge theories.
creator: NEKRASOV
source: P/02/19
publisher: IHES
date: 03/2002
format: A4
format: 14 f.
language: EN
type: TEXTE
type: PREPUBLICATION
coverage: 2002

Target space symmetries in topological theories I.
subject: TOPOLOGIE
subject: SYMETRIE
subject: ESPACE
subject: DIFFEOMORPHISMES
subject: THEORIE DES CHAMPS
description: Abstract : We study realization of the target space diffeomorphisms in the type C topological string. We found that the charges, which generate transformations of the boundary observables, form an algebra, which differs from that of bulk charges by the contribution of the bubbled disks. We discuss applications to noncommutative field theories.
creator: NEKRASOV
creator: BAULIEU
creator: LOSEV
source: P/02/20
publisher: IHES
date: 03/2002
format: A4
format: 13 f.
language: EN
type: TEXTE
type: PREPUBLICATION
coverage: 2002

Seiberg-Witten prepotential from instanton counting
subject: INVARIANTS DE SEIBERG-WITTEN
subject: CHAMPS DE JAUGE
subject: THEORIE DES CHAMPS
description: Abstract : Direct evaluation of the Seiberg-Witten prepotential is accomplished following the localization programme suggested some time ago. Our results agree with all low-instanton calculations available in the literature. We present a two-parameter generalization of the Seiberg-Witten prepotential, which is rather natural from the M-theory/five dimensional perspective, and conjecture its relation to the tau-functions of KP/Toda hierarchy. To Arkady Vainshtein on his 60th anniversary
creator: NEKRASOV
source: P/02/44
publisher: IHES
date: 06/2002
format: A4
format: 14 f.
language: EN
type: TEXTE
type: PREPUBLICATION
coverage: 2002