真空暗能量与宇宙重子数不对称

【作者】 陈驰一；

【导师】 沈有根；

【作者基本信息】 中国科学院研究生院（上海天文台） ， 天体物理， 2005， 博士

【摘要】 结合粒子物理标准模型和现代宇宙学观测最新成果的宇宙学常数问题是目前理论物理学所面临最为严重的问题之一,其中的真空能问题是涉及根本性概念的当前很多矛盾的焦点所在。本文主要就围绕当前宇宙学的两个重要问题展开,一是真空能疑难,二是宇宙中的重子数不对称.其中对于真空能的考虑和当前的暗能量问题结合在了一起.最近的宇宙学观测表明,宇宙中的真空能的上限相比当前粒子物理标准模型所预言的值要远小几十个量级以上。为了缓解这一严重的冲突,本文先讨论了紧致额外维存在的情况下,真空能在高维宇宙学中的动力学性质。然后从粒子物理和场论的角度出发,提出了引力性的Higgs机制,在这个图象中标准的Higgs机制所要求的Higgs场由引力性的标量来替代,得到了和当前实验相容的跑动的真空能密度和跑动的电子质量。此外,在从引力理论角度研究暗能量的过程中,我们产生了把标量性的自发破缺机制和重子数的引力性起源的物理结合起来考虑的想法。应用到宇宙的重子数不对称问题上, 我们通过延续对称性破缺-CPT破坏-重子数自发生成的机制, 提出了Brans-Dicke宇宙中的重子数自发生成。在此模型中,给出的是引力标量或曲率标量与重子流(或轻子流)之间的耦合,而观测所要求的宇宙重子数不对称同样可以得到。更多还原

【Abstract】 The cosmological constant problem, which combining the Standard Model of particlephysics and the latest achievement of modern cosmological observation, is a great crisisfacing theoretical physics. Its related problem of vacuum energy is the focus of severalcontradictions concerning fundamental physics concepts. In this thesis, I will extend thediscussion along two important problems in modern cosmology: the one is the problemof vacuum energy, and the other is the baryon asymmetry in the universe. In addition,the arising dark energy di?culty is also taken into the consideration of the problem ofvacuum energy.Recent cosmological observation has indicated that the upper limit of vacuum energydensity in the universe is tens of magnitudes less than its predicted value from theparticle standard model. To release this severe contradiction, the dynamical propertyof the vacuum energy in the higher dimensional model with compactified extra space isfirstly discussed. Secondly, I will present a new model of Higgs mechanism based on thecomplex scalar gravity theory, which I will show is theoretically natural and provides arunning density of vacuum energy with a survival running speed of mass scale.Thirdly, I will propose a model which connects the gravitational origin of thebaryo/leptogenesis to the spontaneous breaking of gravitational scalar. In this classof models, the baryon asymmetry in the universe is generated along the ideas of sym-metry breaking—CPT violation—spontaneous baryo/leptogenesis. On this basis, weintroduce the spontaneous baryo/leptogenesis into Brans-Dicke cosmology, where thegravitational scalar of Brans-Dicke theory is assumed to be coupled with the current ofbaryon (or lepton). We find that a su?cient baryon asymmetry in the early universecan be obtained in such model.更多还原