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arXiv 0705.4043gr-qc
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类MOND引力的场论公式

Field-theoretical formulations of MOND-like gravity

Jean-Philippe Bruneton, Gilles Esposito-Farese

摘要:

修正的牛顿动力学(MOND)是一种可能的方法来解释平坦的星系旋转曲线,而无需调用暗物质的存在。然而,要在一个没有不稳定性且承认一个适定柯西问题的相容场论中预言这样的现象学是相当困难的。我们严格审查各种建议的文献,并强调他们的成功和失败都从实验和场理论的观点。我们表现出新的困难,在这两种情况下,并指出隐藏的微调的一些模型。另一方面,我们表明,几个出版的不去定理的基础上的假设,这可能是不必要的,使空间的可能的模型是一个先验更大。我们研究了一种新的路线来重现MOND物理,其中的场方程是特别简单的物质外。然而,分析物质内部的场方程(这是一个在文献中经常被遗忘的关键点)表现出一个致命的问题,即它们并不总是双曲的。顺便说一句,我们证明了同样的理论框架提供了一个稳定的和适定的模型,能够重现先锋异常,而不破坏任何广义相对论的精度测试。我们的结论是,在文献中提出的所有MOND类模型,包括本文研究的新模型,都存在严重的困难:它们不仅是不自然的微调,而且它们也无法再现某些实验事实,或者是不稳定的或不一致的场论。然而,一些框架,特别是Bekenstein和Sanders的张量-矢量-标量(TeVeS)框架,似乎比其他框架更有前途,我们的讨论强调了应该在哪些方向上改进它们。

英文摘要:

Modified Newtonian dynamics (MOND) is a possible way to explain the flat galaxy rotation curves without invoking the existence of dark matter. It is however quite difficult to predict such a phenomenology in a consistent field theory, free of instabilities and admitting a well-posed Cauchy problem. We examine critically various proposals of the literature, and underline their successes and failures both from the experimental and the field-theoretical viewpoints. We exhibit new difficulties in both cases, and point out the hidden fine tuning of some models. On the other hand, we show that several published no-go theorems are based on hypotheses which may be unnecessary, so that the space of possible models is a priori larger. We examine a new route to reproduce the MOND physics, in which the field equations are particularly simple outside matter. However, the analysis of the field equations within matter (a crucial point which is often forgotten in the literature) exhibits a deadly problem, namely that they do not remain always hyperbolic. Incidentally, we prove that the same theoretical framework provides a stable and well-posed model able to reproduce the Pioneer anomaly without spoiling any of the precision tests of general relativity. Our conclusion is that all MOND-like models proposed in the literature, including the new ones examined in this paper, present serious difficulties: Not only they are unnaturally fine tuned, but they also fail to reproduce some experimental facts or are unstable or inconsistent as field theories. However, some frameworks, notably the tensor-vector-scalar (TeVeS) one of Bekenstein and Sanders, seem more promising than others, and our discussion underlines in which directions one should try to improve them.

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