超对称变色龙的动力学
Dynamics of Supersymmetric Chameleons
摘要：
研究了一类与冷暗物质费米子耦合的超对称变色龙模型的宇宙动力学。超重力校正确保这些模型在所有感兴趣的天体物理学对象中得到有效筛选，但这并不排除在线性宇宙学尺度上增强重力。我们分析了背景宇宙学，并以封闭形式求解了冷暗物质密度扰动增长的修正方程。利用这一点，我们继续推导出修改后的线性功率谱，其特征在于由两个尺度，地平线大小在物质辐射平等和红移时，变色龙达到其有效电位的最小值。该模型包括一个宇宙学常数的形式的费耶特-伊利奥波洛斯项，出现在晚的时候，由于耦合的变色龙两个带电标量。我们研究的条件下，这导致可行的背景宇宙学，并继续分析偏离LCDM预测的线性制度。我们发现，合理的值在模型的参数空间一般有一个区域，模型的宇宙学是可行的，目前的测量可以重现。一个小的差异，从它的LCDM对应的物质功率谱可以得到在一个较小的子集的参数空间。
英文摘要：
We investigate the cosmological dynamics of a class of supersymmetric chameleon models coupled to cold dark matter fermions. Supergravity corrections ensure that these models are efficiently screened in all astrophysical objects of interest, however this does not preclude the enhancement of gravity on linear cosmological scales. We analyse the background cosmology and solve the modified equations for the growth of cold dark matter density perturbations in closed form. Using this, we go on to derive the modified linear power spectrum which is characterised by two scales, the horizon size at matter-radiation equality and at the redshift when the chameleon reaches the minimum of its effective potential. The model includes a cosmological constant in the form of a Fayet-Illiopolous term, which emerges at late times due to the coupling of the chameleon to two charged scalars. We examine the conditions under which this leads to viable background cosmology and go on to analyse the deviations from the LCDM predictions in the linear regime. We find that for reasonable values in the model's parameter space there is generically a region where the model's cosmology is viable and current measurements can be reproduced. A small discrepancy of the matter power spectrum from its LCDM counterpart can be obtained in a smaller subset of the parameter space.
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