Detecting Extra-dimensions through Cosmic Background Radiation

WMAP最近对宇宙背景辐射的观测有力地支持了暴胀假说的有效性。目前，理论宇宙学中最重要的问题是揭示暴胀。另一方面，人们普遍认为超弦理论是最终的万有统一理论最有希望的候选者。超弦理论最精确的预测是我们的世界是10维的。这意味着额外的6维必须被压缩到小尺寸才能与我们的现实世界相一致。超弦理论的最新发展表明膜世界图景是紧化的一种机制。我们根据这个新的世界图景，即膜世界，揭示了通货膨胀。首先，我们利用自己发明的梯度展开法构造了描述膜世界低能动力学的四维有效理论。然后，利用这一有效理论，我们分析了两个膜世界的碰撞过程。在碰撞点，我们使用了纯5维分析。关键是我们已经建立了几何膨胀模型。在我们的暴胀模型中，暴胀是由体积内的通量引起的，并因膜世界的碰撞而终止。碰撞产生的热量点燃了宇宙的大爆炸。我们还计算了量子过程在快速膨胀过程中产生的宇宙学扰动，并表明预测与目前的观测结果一致。

Recent observation on cosmic background radiation by WMAP strongly supports the validity of the inflationary scenario. Nowadays, the most important issue in theoretical cosmology is to unveil the inflaton. On the other hand, it is widely believed that the superstring theory is the most promising candidate of the ultimate unified theory of everything. The most precise prediction of superstring theory is that our world is 10-dimensions. That means the extra 6-dimensions must be compactified to the small size to reconcile with our real world. Recent developments of superstring theory suggest the braneworld picture as a mechanism of compactification. We have unveiled the inflaton based on this new picture of the world, namely braneworld. Firstly, we have constructed the 4-dimensional effective theory describing the low energy dynamics of the braneworld by using the gradient expansion method invented by us. Then, using this effective theory, we have analyzed the collision process of two braneworlds. At the collision point, we have utilized the purely 5-dimensional analysis. The point is that we have constructed the geometrical inflation model. In our inflationary model, Inflation is caused by the flux in the bulk and terminated by the collision of braneworlds. The heat produced by the collision ignites the big-bang of our universe. We have also calculated the cosmological perturbations produced by the quantum process during rapid expansion and shown that the predictions are consistent with the present observations.