We analyse the process of reheating the Universe in the electroweak theory where the Higgs field plays a role of the inflaton. We estimate the maximal temperature of the Universe and fix the initial conditions for radiation-dominated phase of the Universe expansion in the framework of the Standard Model (SM) and of the nuMSM -- the minimal extension of the SM by three right-handed singlet fermions. We show that the inflationary epoch is followed by a matter dominated stage related to the Higgs field oscillations. We investigate the energy transfer from Higgs-inflaton to the SM particles and show that the radiation dominated phase of the Universe expansion starts at temperature T_r~(3-15)*10^{13} GeV, where the upper bound depends on the Higgs boson mass. We estimate the production rate of singlet fermions at preheating and find that their concentrations at T_r are negligibly small. This suggests that the sterile neutrino Dark Matter (DM) production and baryogenesis in the nuMSM with Higgs-driven inflation are low energy phenomena, having nothing to do with inflation. We study then a modification of the nuMSM, adding to its Lagrangian higher dimensional operators suppressed by the Planck scale. The role of these operators in Higgs-driven inflation is clarified. We find that these operators do not contribute to the production of Warm Dark Matter (WDM) and to baryogenesis. We also demonstrate that the sterile neutrino with mass exceeding 100 keV (a Cold Dark Matter (CDM) candidate) can be created during the reheating stage of the Universe in necessary amounts. We argue that the mass of DM sterile neutrino should not exceed few MeV in order not to overclose the Universe.
Chaotic Amplification of Neutrino Chemical Potentials by Neutrino Oscillations in Big Bang Nucleosynthesis
我们详细研究了在大爆炸核合成时期放大中微子化学势的活动无菌中微子振荡的参数空间。我们计算了放大的幅度，并显示在放大过程中的混沌的证据。我们还讨论了中微子化学势放大在大爆炸核合成中的意义。它表明，与$\sim 1$ eV $\nue$，其化学势的放大，由活跃的无菌中微子振荡可以降低中微子物种在大爆炸核合成的有效数量显着低于3。
Generating Ekpyrotic Curvature Perturbations Before the Big Bang
我们分析了在大爆炸前的收缩阶段产生几乎尺度不变的宇宙学曲率扰动谱的一般机制，它可以完全用4d有效场论来描述。该机制基于首先产生熵扰动，然后将其转换为曲率扰动，可以自然地纳入循环和ekpyrotic模型，其中大爆炸被建模为膜碰撞，以及其他类型的宇宙学模型与前大爆炸阶段。我们证明了可以获得正确的扰动振幅，并且标量光谱倾斜n的范围往往从略蓝到红色，对于最简单的模型，0.97 < n < 1.02，这个范围与当前的观测结果相一致，但与最简单的大场暴胀模型的预测相比，向蓝色移动了百分之几。
