In this work, we study interaction between dark energy and dark matter, where dark energy is described by a massive vector field, and dark matter is modelled as a fluid. We present a new interaction term, which affects only perturbations and can give interesting phenomenology. Then we present a general Lagrangian for the interacting vector dark energy with dark matter. For the dark energy, we choose Proca theory with G ₃ term to study its phenomenological consequence. For this model, we explore both background and perturbation dynamics. We also present the no-ghost condition for tensor modes, vector modes and scalar modes. Subsequently, we also study the evolution of the overdensities of both baryon and cold dark matter in the high-k limit. We show that the effective gravitational coupling is modified for cold dark matter and baryon. We also choose a simple concrete model and numerically show a suppression of the effective gravitational coupling for cold dark matter. However, in this simple model, the suppression of the effective gravitational coupling does not result in a suppression of the matter overdensity compared to that in the ΛCDM model due to the modified background expansion.

中文翻译：

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向量暗能与流体相互作用的理论


在这项工作中，我们研究了暗能量和暗物质之间的相互作用，其中暗能量由大质量矢量场描述，而暗物质被建模为流体。我们提出了一个新的交互项，它只影响扰动，并且可以给出有趣的现象学。然后，我们提出了一个与暗物质相互作用的向量暗能量的广义拉格朗日。对于暗能量，我们选择带有 G₃ 项的 Proca 理论来研究其现象学后果。对于这个模型，我们探索了背景动力学和扰动动力学。我们还提出了张量模式、向量模式和标量模式的无重影条件。随后，我们还研究了重子和冷暗物质在高 k 极限下的超密度演化。我们表明，针对冷暗物质和重子的有效引力耦合进行了修改。我们还选择了一个简单的具体模型，并以数值方式显示了冷暗物质的有效引力耦合的抑制。然而，在这个简单的模型中，由于 ΛCDM 模型中修改了背景膨胀，有效引力耦合的抑制并不会导致物质过密度的抑制。