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arXiv 0705.2346hep-th
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作为西格玛模型和无张力极限的弦

Strings as sigma models and in the tensionless limit

Jonas Persson

摘要:

这篇论文考虑了弦论的两个不同方面,弦的无张力极限和超对称西格玛模型。无张力极限被用来寻找由无张力弦产生的IIB超重力背景。在pp波背景下对无张力弦进行量子化,发现无张力极限与量子化可互换。进一步,考虑了N=(2,2)扩展世界片超对称性的西格玛模型,并讨论了目标空间具有双厄米几何的要求.它表明,双厄米几何和广义Kahler之间的等价性如下,在这种情况下,从拉格朗日和哈密顿制定的模型之间的等价性。此外,显式T-对偶变换的哈密顿制定的西格玛模型的构造和证明是一个辛同胚。在一定的假设下,在西格玛模型中存在的扩展超对称性的量被证明是T-对偶下保存。此外,通过要求N=(2,2)扩展的超对称性在一阶制定的西格玛模型一个有趣的几何结构出现,并在特殊情况下,广义复杂的几何被发现包含在新的框架。

英文摘要:

This thesis considers two different aspects of string theory, the tensionless limit of the string and supersymmetric sigma models. The tensionless limit is used to find a IIB supergravity background generated by a tensionless string. Quantization of the tensionless string in a pp-wave background is performed and the tensionless limit is found to commute with quantization. Further, the sigma model with N=(2,2) extended world-sheet supersymmetry is considered and the requirement on the target space to have a bi-Hermitean geometry is reviewed. It is shown that the equivalence between bi-Hermitean geometry and generalized Kahler follows, in this context, from the equivalence between the Lagrangian- and Hamiltonian formulation of the model. Moreover, the explicit T-duality transformation in the Hamiltonian formulation of the sigma model is constructed and shown to be a symplectomorphism. Under certain assumptions, the amount of extended supersymmetry present in the sigma model is shown to be preserved under T-duality. Further, by requiring N=(2,2) extended supersymmetry in a first order formulation of the sigma model an intriguing geometrical structure arises and in a special case generalized complex geometry is found to be contained in the new framework.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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