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arXiv hep-ph/0201014hep-ph
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宇宙中的SUSY暗物质-理论直接探测率

SUSY Dark Matter in the Universe- Theoretical Direct Detection Rates

J. D. Vergados

摘要:

奇异的暗物质与真空能量或宇宙学常数一起似乎在宇宙中占主导地位。更高密度的这种物质似乎被引力困在银河系中。因此,直接探测它是粒子物理学和宇宙学的核心。目前的超对称模型提供了一个自然的暗物质候选者,这是最轻的超对称粒子(LSP)。这样的模型结合了相当好理解的物理学,如核子的夸克子结构和原子核结构(形状因子和/或自旋响应函数),允许评估LSP-原子核弹性散射的事件率。然而,由此获得的事件发生率非常低,甚至无法检测。因此,必须利用调制效应,即事件率对地球年运动的依赖性。考虑方向率也是有用的,即它与反冲核方向的关系。在本文中,我们研究了这种调制效应在无方向性和方向性的实验。我们计算的微分和总速率使用等温的,对称的,以及只有轴向不对称的,和非等温的,由于焦散环,速度分布。我们发现,在对称的情况下,调制幅度是小的。焦散环的情况也是如此。不对称的列入,与现实增强的速度分散在银河系的方向,产生增强的调制效果,特别是在定向实验。

英文摘要:

Exotic dark matter together with the vacuum energy or cosmological constant seem to dominate in the Universe. An even higher density of such matter seems to be gravitationally trapped in the Galaxy. Thus its direct detection is central to particle physics and cosmology. Current supersymmetric models provide a natural dark matter candidate which is the lightest supersymmetric particle (LSP). Such models combined with fairly well understood physics like the quark substructure of the nucleon and the nuclear structure (form factor and/or spin response function), permit the evaluation of the event rate for LSP-nucleus elastic scattering. The thus obtained event rates are, however, very low or even undetectable. So it is imperative to exploit the modulation effect, i.e. the dependence of the event rate on the earth's annual motion. Also it is useful to consider the directional rate, i.e its dependence on the direction of the recoiling nucleus. In this paper we study such a modulation effect both in non directional and directional experiments. We calculate both the differential and the total rates using both isothermal, symmetric as well as only axially asymmetric, and non isothermal, due to caustic rings, velocity distributions. We find that in the symmetric case the modulation amplitude is small. The same is true for the case of caustic rings. The inclusion of asymmetry, with a realistic enhanced velocity dispersion in the galactocentric direction, yields an enhanced modulation effect, especially in directional experiments.

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