15,202 research outputs found

    Noncommutative and Non-Anticommutative Quantum Field Theory

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    A noncommutative and non-anticommutative quantum field theory is formulated in a superspace, in which the superspace coordinates satisfy noncommutative and non-anticommutative relations. A perturbative scalar field theory is investigated in which only the non-anticommutative algebraic structure is kept, and one loop diagrams are calculated and found to be finite due to the damping caused by a Gaussian factor in the propagator.Comment: 12 pages LaTex. No figures. Revised text. Conclusions remain the same. Misprint in Eq.(31) correcte

    Noncommutative Quantum Gravity

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    The possible role of gravity in a noncommutative geometry is investigated. Due to the Moyal *-product of fields in noncommutative geometry, it is necessary to complexify the metric tensor of gravity. We first consider the possibility of a complex Hermitian, nonsymmetric gμνg_{\mu\nu} and discuss the problems associated with such a theory. We then introduce a complex symmetric (non-Hermitian) metric, with the associated complex connection and curvature, as the basis of a noncommutative spacetime geometry. The spacetime coordinates are in general complex and the group of local gauge transformations is associated with the complex group of Lorentz transformations CSO(3,1). A real action is chosen to obtain a consistent set of field equations. A Weyl quantization of the metric associated with the algebra of noncommuting coordinates is employed.Comment: 13 pages LaTex. Changes to text and new text added. To be published in Physics Letters

    Nonsymmetric Gravitational Theory

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    A new version of nonsymmetric gravitational theory is presented. The field equations are expanded about the Minkowski metric, giving in lowest order the linear Einstein field equations and massive Proca field equations for the antisymmetric field g[μν]g_{[\mu\nu]}. An expansion about an arbitrary Einstein background metric yields massive Proca field equations with couplings to only physical modes. It follows that the new version of NGT is free of ghost poles, tachyons and higher-order poles and there are no problems with asymptotic boundary conditions. A static spherically symmetric solution of the field equations in the short-range approximation is everywhere regular and does not contain a black hole event horizon.Comment: 11 pages plain TeX. TeX macrofile included. Corrections in formula

    Multiple reading: text and theory

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    It was with great pleasure that I accepted an invitation to run a workshop at the recent NZATE Conference. The topic of my session was an overview of the use of literary theory in the teaching of English and that same focus directs this written version of my presentation. I approach this topic not as a theory guru or expert, but as a practitioner who has found that an understanding and application of theory has made me a better teacher. In particular, I believe that judicious use of theory enables me to communicate to students the diverse ways in which written and visual texts can be read, encouraging them to think for themselves in a fresh and original manner and to see points of connection between a range of texts. Combined with the essential critical tools of close reading and textual analysis and support, a knowledge of theory helps students to think critically and to shape informed, coherent arguments

    Five imperial adventures in the Waikato

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    Some late nineteenth-century exponents of the 'Novel of Adventure', or imperial adventure-romance, regarded colonial New Zealand as an attractive canvas for their tales of masculine daring in an exotic, rugged environment.3 Five such authors set their narratives, in part or in full, in the Waikato of the 1860s, drawn to the backdrop of inter-racial conflict provided by the New Zealand Wars. While references to specific events and people associated with colonial Waikato do ground many of these texts in historical reality, it has to be said that, regardless of whether the authors write from experience, careful research, or flights of imaginative fantasy, the Waikato that is described in their narratives has been selected for its frontier possibilities rather than its distinctive geography

    Instrument or object? The New Zealand piano on display

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    The piano is rather a unique display item in the museum or the historic house. Firstly, whether an upright or a grand, the piano is an imposing, substantial object that occupies significant space within a setting and immediately demands attention because of its proportions. This object has a history, a story to tell that, where the provenance of the piano is known, provides a direct, tangible link with the past. Secondly, the piano is an aesthetic object, finely crafted and giving pleasure to the eye through the grain of the wood, the sheen of the polish, the black and white chessboard of the keyboard, the intricacy of the carved legs or marquetry inlay, the elegance of its shape and design. Finally, it is a musical instrument designed to produce sound and thus has the potential to delight the ear as well as the eye. Indeed, sight and sound are not the only senses to be satisfied by the instrument. The musty perfume of old wood and the sharp tang of lacquer entice the nose, while the satin wood and cool ivory keys please the fingers. It is through touch, the interplay between the body and the instrument, with hands on the keys and feet on the pedals, that a piano is given voic

    Superluminal Gravitational Waves

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    The quantum gravity effects of vacuum polarization of gravitons propagating in a curved spacetime cause the quantum vacuum to act as a dispersive medium with a refractive index. Due to this dispersive medium gravitons acquire superluminal velocities. The dispersive medium is produced by higher derivative curvature contributions to the effective gravitational action. It is shown that in a Friedmann-Lema\^{i}tre-Robertson-Walker spacetime in the early universe near the Planck time tPL1043sect_{\rm PL}\gtrsim 10^{-43}\,{\rm sec}, the speed of gravitational waves cgcg0=c0c_g\gg c_{g0}=c_0, where cg0c_{g0} and c0c_0 are the speeds of gravitational waves and light today. The large speed of gravitational waves stretches their wavelengths to super-horizon sizes, allowing them to be observed in B-polarization experiments.Comment: 5 pages, no figure
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