宇宙加速是由外来的无质量粒子引起的吗？
Can cosmic acceleration be caused by exotic massless particles?
摘要：
为了描述暗能量，我们在微观水平上引入了一个没有自由参数的流体模型。这种流体的成分是无质量的粒子，它们是未扩展的$D=(3+1)$伽利略代数的动力学实现。这些粒子是外来的，因为它们生活在一个扩大的相空间中。它们唯一的相互作用就是引力。满足爱因斯坦等效原理的与引力场的最小耦合，会导致动态活动的引力质量密度。一个包含物质（重子和暗物质）和暗能量的双组分模型，通过宇宙学原理，导出了类似弗里德曼的方程。他们的解显示了早期宇宙的减速阶段和晚期宇宙的加速阶段。我们预测的哈勃参数$H(z)/H_0$和减速参数$q(z)$，并与现有的实验数据进行比较。我们还讨论了一个简化的模型（一个组件的黑暗部门）和包括辐射。我们的模型没有显示出牛顿引力势的稳态修正。
英文摘要：
To describe dark energy we introduce a fluid model with no free parameter on the microscopic level. The constituents of this fluid are massless particles which are a dynamical realisation of the unextended $D=(3+1)$ Galilei algebra. These particles are exotic as they live in an enlarged phase space. Their only interaction is with gravity. A minimal coupling to the gravitational field, satisfying Einstein's equivalence principle, leads to a dynamically active gravitational mass density of either sign. A two-component model containing matter (baryonic and dark) and dark energy leads, through the cosmological principle, to Friedmann-like equations. Their solutions show a deceleration phase for the early universe and an acceleration phase for the late universe. We predict the Hubble parameter $H(z)/H_0$ and the deceleration parameter $q(z)$ and compare them with available experimental data. We also discuss a reduced model (one component dark sector) and the inclusion of radiation. Our model shows no stationary modification of Newton's gravitational potential.
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