Brans-Dicke宇宙中的轻子数生成(英文)  

Spontaneous Leptogenesis in Brans-Dicke Cosmology

作　　者：陈驰一[1] 沈有根[1] 冯波 

机构地区：[1]中国科学院上海天文台,上海200030 [2]中国科学院研究生院

出　　处：《高能物理与核物理》2005年第11期1033-1040,共8页High Energy Physics and Nuclear Physics

基　　金：国家自然科学基金(10273017)~~

摘　　要：讨论了Brans-Dicke理论中的辅助性标量φ在宇宙的重子数不对称起源中所扮演的可能角色。在Morganstern关于Brans-Dicke(BD)宇宙学的一系列工作的基础上,讨论了这个引力性标量场的导数和重子流J_B~μ或者“重子-轻子”流J_(B-L)~μ的耦合效应。发现由这个耦合形成的自发重子数生成机制,只要其中大统一发生的时标足够提前,就可以产生足够的重子数不对称n_B/s～10^(-10)。此外,也研究了由Davoudiasl引进的里奇标量R的导数和重子流之间的相互作用耦合在辐射为主的BD宇宙中的重子数生成效应。结果表明,在此情况下因为R不再为零也同样可以获得重子数的不对称,从而不同于爱因斯坦宇宙框架下的相关结论。The role of the auxiliary scalar field φ of BD theory in baryon number asymmetry is discussed in this paper. We consider a derivative coupling of this gravitational scalar field to the baryon current J^μB or the current of the baryon number minus lepton number J^μB-L based on a series of works of R. Morganstern about the Brans-Dicke cosmology. We find that the spontaneous baryogenesis by this coupling is able to yield sufficient baryon asymmetry nB/s - 10^-10 provided the time of the grand unification is a little bit earlier. In addition, Davoudiasl et al have recently introduced a new type of interaction between the Ricci scalar R and the bayon current J^μ,δμRJ^μ and also proposed a mechanism for baryogenesis, the gravitational baryogenesis. However, the Einstein equation tells us that R^·=0 in the radiation-dominated epoch of the standard FRW cosmology. In this paper we reconsider the feasibility of having gravitational baryongenesis with such a form of interaction in radiation-filled BD cosmology. We show that R^· does not vanish in this case and the required baryon number asymmetry can also be achieved.

关 键 词：轻子数生成 标量耦合 Brans—Dicke宇宙学 宇宙学 轻子 耦合效应 重子数 不对称 标量场 相互作用 

分 类 号：O572.32[理学—粒子物理与原子核物理] P159[理学—物理]