标题： 宇宙早期阶段的热力学和宇宙学参数 显示英文标题

标题： Thermodynamic and cosmological parameters of early stages of the Universe

摘要： 早期宇宙的特点是存在大量在不同温度下脱离平衡的粒子，这导致了宇宙的不同阶段。 这对表征早期宇宙每个阶段热力学和宇宙学参数的时间演化产生了影响。 在这项研究中，我们推导出了描述宇宙早期（即辐射时代、夸克-胶子等离子体时代、强子时代和混合时代）这些参数时间演化的方程的解析表达式。 所涉及的参数包括能量密度、熵密度、温度、压力以及哈勃参数和尺度因子。 有了这些表达式，我们可以估算出宇宙每个时代的开始和结束时间，这将在本文中展示。 显示英文摘要

摘要： The early Universe was characterized by the presence of heavy particles that decoupled at different temperatures leading to different phases of the Universe. This had a consequences on the time evolution of the thermodynamic and the cosmological parameters characterizing each phase of the early Universe. In this study, we derive the analytic expressions of the equations governing the time evolution of these parameters in the early eras of the Universe namely, the radiation era, the quark-gluon plasma era, the hadron era and the mixed era. The parameters under concern include the energy density, the entropy density, the temperature, the pressure in addition to Hubble parameter and the scale factor. Having these expressions allows us to give estimations of the times corresponding to the beginning and ending of each era of the Universe as will be presented in this work.