Non-Commutative Gravity  

In General > s.a. 2D gravity; 3D gravity; action for general relativity.
* Motivation: May be able to "smoothly" interpolate between different spatial topologies.
* Einstein equation: The effects of non-commutativity can be taken into account by keeping the standard form of the Einstein tensor on the left-hand side of the equation and introducing a modified energy-momentum tensor as a source on the right-hand side.
* Remark: The Wodzicki residue of D–2, with D the Dirac operator, is proportional to the Einstein-Hilbert action [@ Kastler CMP(95)].
@ Reviews: Fröhlich et al ht/97-ln; Chamseddine AIHP(03)ht-in; Meyer ht/05-in; Yang MPLA(07)ht/06; Vassilevich a0902-in; Franco a0904-in.
@ General references: Gervais NPB(87); Chamseddine et al CMP(93); Landi et al PLB(94); Mohammedi MPLA(94); Sitarz CQG(94)ht; Connes CMP(96)ht [matter]; Madore NPPS(97)gq/96, gq/97; Bimonte et al NPB(98)ht/97, PLB(98)gq; Jevicki & Ramgoolam JHEP(99) [from AdS-cft]; Nair NPB(03)ht/01; Cardella & Zanon CQG(03)ht/02 [deformation]; Rivelles PLB(03)ht/02; Chamseddine JMP(03) [action]; Avramidi PLB(03)ht [deformation]; Aschieri et al CQG(05)ht [metric, curvature, torsion, action], CQG(06)ht/05, Aschieri JPCS(06)ht [deformed diffeomorphisms]; Calmet & Kobakhidze PRD(05)ht [general relativity]; Kobakhidze IJMPA(08)ht/06; Harikumar & Rivelles CQG(06)ht [and non-associative]; Mukherjee & Saha PRD(06) [non-commutative corrections]; Fucci & Avramidi CQG(08)-a0708 [non-commutative Einstein equation]; Kobakhidze a0905 [diffeomorphism-invariant version, with twisted local Lorentz invariance]; Aschieri & Castellani a0906 [solutions].
@ Cosmological constant: Yang a0711 [from fluctuations, emergent gravity]; Mena et al a0802.
@ Linearized gravity: Ferrari et al PLB(07)ht/06 [Lorentz violation and torsion]; > s.a. modified quantum gravity.
@ And other fields: Brandt & Elias PRD(06)ht [scalar-graviton interaction]; Yang JHEP(09)-a0809 [and electromagnetism, emergent gravity]; Aschieri & Castellani JHEP(09)-a0902 [coupled to fermions], JHEP(09)-a0902 [3D and 4D supergravity].
@ From string theory: Álvarez-Gaumé et al NPB(06).
@ From other theories: Yang ht/06, IJMPA(09)ht/06 [from self-dual electromagnetism]; Steinacker JHEP(07)-a0708 [from non-commutative U(n) gauge theory].
@ Black holes: Nozari & Fazlpour MPLA(07)ht/06 [evaporating]; López-Domínguez et al PRD(06)ht [Schwarzschild, and thermodynamics]; Dolan et al CQG(07) [BTZ, and discrete time]; Chaichian et al PLB(08)-a0710, Kobakhidze PRD(09)-a0712 [corrections to Schwarzschild]; Mukherjee & Saha PRD(08)-a0710 [corrections to Reissner-Nordström]; Chaichian et al JHEP(08) [including cosmological constant]; Nicolini IJMPA(09)-a0807 [rev]; Estrada-Jiménez et al PRD(08) [twisted, covariant, self-dual]; Schupp & Solodukhin a0906 [exact solutions]; Ohl & Schenkel JHEP(09)-a0906 [twisted]; Alavi APPB(09)-a0909 [Reissner-Nordström]; > s.a. black-hole radiation; schwarzschild solution.
@ Cosmology: Marcolli & Pierpaoli a0908 [early universe]; > s.a. friedmann equation; inflation; non-commutative physics.
@ Related topics: Rivelles AIP(05)ht/04 [and Seiberg-Witten map]; Zupnik CQG(07) [reality]; > s.a. Star Product.

Quantum Gravity > s.a. discrete models; photons in quantum gravity.
@ General references: Moffat PLB(00)ht, PLB(00)ht [perturbative]; Vassilevich NPB(02) [2D, Moyal]; Pimentel & Mora GRG(05)gq/04 [string theory quantum cosmology]; Heller et al IJTP(05)gq, GRG(04)gq/05, JMP(05); Martinetti MPLA(05)gq-in [and thermal time hypothesis]; Aastrup & Grimstrup IJMPA(07)ht/06, Chamseddine & Connes PRL(07) [boundary terms from spectral action], a0812 [introduction and overview].
@ And lqg: Aastrup et al CQG(09)-a0802, JNCG(09)-a0802, CQG(09)-a0902-in.
@ Bianchi I models: Guzmán et al IJMPD(07); Socorro et al IJTP-a0910 [with scalar, and fluid]; > s.a. bianchi-I models [Kasner].
@ Kantowski-Sachs models: García-Compeán et al PRL(02), Barbosa & Pinto-Neto PRD(04)ht.
@ Other quantum cosmology: Vakili et al CQG(07)gq; Agüero et al IJTP(07)gq [Bianchi II]; Zejak & Dragovich a0708 [minisuperspace]; Fabi et al PRD(08)-a0808 [corrections to FRW metrics]; Bastos et al PRD(08)-a0712, a0904-in [phase-space non-commutative]; Mena et al IJMPD(09) [WKB-type approximation]; > s.a. bianchi IX models; friedmann equation; relativistic cosmology; quantum cosmology.
@ 3D: Schroers PoS-a0710 [phase-space non-commutativity]; > s.a. 3D quantum gravity.
@ And quantum mechanics: Heller et al JMP(00)ht/99; Singh et al gq/05 [non-linear].
@ Phenomenology: Heller & Sasin gq/97, GRG(99)gq/98 [and singularities]; Girelli & Livine gq/04, Girelli et al NPB(05)gq [low-energy limit]; Heller et al JMP(07) [malicious singularities]; > s.a. kaluza-klein phenomenology; Pioneer anomaly.

Other Aspects
@ Large extra dimensions: Lizzi et al MPLA(01)ht/00 [Randall-Sundrum].


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