明天Andy Strominger来，下午要做公众报告，估计没有时间更新博客了。和学生们刚完成两个文章，一篇刚放到arXiv，明天出现，所以下面的链接暂时空着，明天文章出来了再补。这篇文章是研究中国人提出的三种holographic dark energy模型，一个是我的，一个是蔡荣根和韦浩等人的，一个是高长军和陈学雷等人的。

Holographic dark energy models: A comparison from the latest observational data

这篇文章的作者有四位：本博，李霄栋，王爽，张鑫。张鑫已经是东北大学的教授了。为了偷懒，我将英文摘要拷贝如下：

The holographic principle of quantum gravity theory has been applied to the dark energy (DE) problem, and so far three holographic DE models have been proposed: the original holographic dark energy (HDE) model, the agegraphic dark energy (ADE) model, and the holographic Ricci dark energy (RDE) model. In this work, we perform the best-fit analysis on these three models, by using the latest observational data including the Union+CFA3 sample of 397 Type Ia supernovae (SNIa), the shift parameter of the cosmic microwave background (CMB) given by the five-year Wilkinson Microwave Anisotropy Probe (WMAP5) observations, and the baryon acoustic oscillation (BAO) measurement from the Sloan Digital Sky Survey (SDSS). The analysis shows that for HDE, ; for RDE, ; for ADE, . Among these models, HDE model can give the smallest . Besides, we also use the Bayesian evidence (BE) as a model selection criterion to make a comparison. It is found that for HDE, ADE, and RDE, , -5.17, and -8.14, respectively. So, it seems that the HDE model is more favored by the observational data.

从摘要看，HDE要明显好于AED和RDE，因为要小得多，贝叶斯证据表明和宇宙学常数比，HDE稍差些（因为多了一个参数），而另外两个模型在5之外了。出现这种情况的原因很简单，HED一般变化慢些（更接近宇宙学常数），而另外另个暗能量随时间的变化要快。

当然，目前的数据还很难说明问题，也许今后更多的数据会改善另外两个模型的处境，当然也有恶化另外两个模型的处境的可能。

第二篇文章应该在后天出现在arXiv上，三位作者：本博，庞毅，王一。文章的题目是：

Non-Commutativity, Teleology and GRB Time Delay

这篇文章完全改好了，没有放上去的原因是没有预印本号（第一篇也没有）。这篇文章内容和我在博文《光子》介绍的gamma爆的光子延迟时间有关。我们用非对易时空来解释光子延迟。题目中的teleology是目的论的意思。用这个词的原因是，如果某些光子的速度大于光速，那么存在一个惯性参照系，其中看这个光子，因果会颠倒。

同样，为了偷懒，我将英文摘要在这里“剧透”：

We propose a model in which an energy-dependent time delay of a photon originates from space-time

noncommutativity, the time delay is due to a noncommutative coupling between dilaton and photon. We predict that in our model, high energy photons with different momenta can either be delayed or superluminal, this may be related to a possible time delay reported by the Fermi LAT and Fermi GBM Collaborations.