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42
Lightcone description of (2,0) superconformal theories in six dimensions
 Adv. Theor. Math. Phys
, 1998
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Towards a noncommutative geometric approach to matrix compactification, Phys. Rev. D58
, 1998
"... In this paper we study generic M(atrix) theory compactifications that are specified by a set of quotient conditions. A procedure is proposed, which both associates an algebra to each compactification and leads deductively to general solutions for the matrix variables. The notion of noncommutative ge ..."
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Cited by 39 (6 self)
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In this paper we study generic M(atrix) theory compactifications that are specified by a set of quotient conditions. A procedure is proposed, which both associates an algebra to each compactification and leads deductively to general solutions for the matrix variables. The notion of noncommutative geometry on the dual space is central to this construction. As examples we apply this procedure to various orbifolds and orientifolds, including ALE spaces and quotients of tori. While the old solutions are derived in a uniform way, new solutions are obtained in several cases. Our study also leads to a new formulation of gauge theory on quantum spaces. 1
Four graviton scattering amplitude from S(N) R**8 supersymmetric orbifold sigma model,” Nucl. Phys. B524
, 1998
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Gravity on fuzzy spacetime
, 1992
"... Dedicated to Walter Thirring on the occasion of his 70th birthday A review is made of recent efforts to add a gravitational field to noncommutative models of spacetime. Special emphasis is placed on the case which could be considered as the noncommutative analog of a parallelizable spacetime. It i ..."
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Cited by 17 (0 self)
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Dedicated to Walter Thirring on the occasion of his 70th birthday A review is made of recent efforts to add a gravitational field to noncommutative models of spacetime. Special emphasis is placed on the case which could be considered as the noncommutative analog of a parallelizable spacetime. It is argued that, at least in this case, there is a rigid relation between the noncommutative structure of the spacetime on the one hand and the nature of the gravitational field which remains as a ‘shadow ’ in the commutative limit on the other. ESI Preprint 478 (1997). Lecture given at the International Workshop “Mathematical
Why the Quantum Must Yield to Gravity
"... After providing an extensive overview of the conceptual elements – such as Einstein’s ‘hole argument ’ – that underpin Penrose’s proposal for gravitationally induced quantum state reduction, the proposal is constructively criticised. Penrose has suggested a mechanism for objective reduction of quan ..."
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Cited by 9 (1 self)
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After providing an extensive overview of the conceptual elements – such as Einstein’s ‘hole argument ’ – that underpin Penrose’s proposal for gravitationally induced quantum state reduction, the proposal is constructively criticised. Penrose has suggested a mechanism for objective reduction of quantum states with postulated collapse time τ = ¯h/∆E, where ∆E is an illdefinedness in the gravitational selfenergy stemming from the profound conflict between the principles of superposition and general covariance. Here it is argued that, even if Penrose’s overall conceptual scheme for the breakdown of quantum mechanics is unreservedly accepted, his formula for the collapse time of superpositions reduces to τ → ∞ (∆E → 0) in the strictly Newtonian regime, which is the domain of his proposed experiment to corroborate the effect. A suggestion is made to rectify this situation. In particular, recognising the cogency of Penrose’s reasoning in the domain of full ‘quantum gravity’, it is demonstrated that an appropriate experiment which could in principle corroborate his argued ‘macroscopic ’ breakdown of superpositions is not the one involving nonrotating mass distributions as he has suggested, but a Leggetttype SQUID or BEC
Dbrane actions on Kahler manifolds
 Adv. Theor. Math. Phys
, 1998
"... We consider actions for N Dbranes at points in a general Kähler manifold, which satisfy the axioms of Dgeometry, and could be used as starting points for defining Matrix theory in curved space. We show that the axioms cannot be satisfied unless the metric is Ricci flat, and argue that such actions ..."
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Cited by 8 (3 self)
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We consider actions for N Dbranes at points in a general Kähler manifold, which satisfy the axioms of Dgeometry, and could be used as starting points for defining Matrix theory in curved space. We show that the axioms cannot be satisfied unless the metric is Ricci flat, and argue that such actions do exist when the metric is Ricci flat. This may provide an argument for Ricci flatness in Matrix theory. August
Matrix Theory on NonOrientable Surfaces
, 1997
"... We construct the Matrix theory descriptions of Mtheory on the Möbius strip and the Klein bottle. In a limit, these provide the matrix string theories for the CHL string and an orbifold of type IIA string theory. ..."
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Cited by 7 (0 self)
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We construct the Matrix theory descriptions of Mtheory on the Möbius strip and the Klein bottle. In a limit, these provide the matrix string theories for the CHL string and an orbifold of type IIA string theory.
Topology at the Planck Length
, 1998
"... A basic arbitrariness in the determination of the topology of a manifold at the Planck length is discussed. An explicit example is given of a ‘smooth ’ change in topology from the 2sphere to the 2torus through a sequence of noncommuting geometries. Applications are considered to the theory of Dbr ..."
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Cited by 5 (4 self)
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A basic arbitrariness in the determination of the topology of a manifold at the Planck length is discussed. An explicit example is given of a ‘smooth ’ change in topology from the 2sphere to the 2torus through a sequence of noncommuting geometries. Applications are considered to the theory of Dbranes within the context of the proposed M(atrix) theory.
Do Quarks Obey DBrane Dynamics
"... The potential between two D0branes at rest is calculated to be a linear. Also the potential between two fast decaying D0branes is found in agreement with phenomenology. 1 ..."
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The potential between two D0branes at rest is calculated to be a linear. Also the potential between two fast decaying D0branes is found in agreement with phenomenology. 1
D0Branes As LightFront Confined Quarks
 Euro. Phys. J. C
"... We argue that different aspects of LightFront QCD at confined phase can be recovered by the Matrix Quantum Mechanics of D0branes. The concerning Matrix Quantum Mechanics is obtained from dimensional reduction of pure YangMills theory to 0+1 dimension. The aspects of QCD dynamics which are studied ..."
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Cited by 3 (3 self)
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We argue that different aspects of LightFront QCD at confined phase can be recovered by the Matrix Quantum Mechanics of D0branes. The concerning Matrix Quantum Mechanics is obtained from dimensional reduction of pure YangMills theory to 0+1 dimension. The aspects of QCD dynamics which are studied in correspondence with D0branes are: 1) phenomenological interquark potentials, 2) whiteness of hadrons and 3) scattering amplitudes. In addition, some other issues such as the largeN behavior, the gravity–gauge theory relation and also a possible justification for involving “noncommutative coordinates ” in a study of QCD boundstates are discussed.