论文标题
辐射主导宇宙初始温度的上限
An Upper Limit on the Initial Temperature of the Radiation-Dominated Universe
论文作者
论文摘要
引力波（GWS）是通过通过电磁Bremsstrahlung的重力类似物碰撞颗粒来产生的。我们计算辐射主导的宇宙中自由发射对随机GW背景的贡献。我们发现，所得GW辐射的能量密度在很大程度上取决于基本粒子的数量，$ n _ {\ mathrm {tot}} $和最大初始温度，$ t _ {\ mathrm {max {max}} $。我们排除$ n _ {\ mathrm {tot}} \ gtrsim n _ {\ mathrm {sm}} $ for $ t _ {\ mathrm {max}} \ sim t _ {\ sim t _ {\ sim t _ {\ sim t _ { $ n _ {\ mathrm {tot}} \ gtrsim10^{13} \ times n _ {\ mathrm {sm}} $ for $ t _ {\ t _ {\ mathrm {max}}}} \ sim10^{16} $ gev，其中$ n _ IS $ n _ istormy of norderles narorde norderles in Storande cons in Storande of strumend}在通货膨胀的情况下，现有的宇宙学数据限制$ t _ {\ mathrm {max}} \ Lessim10^{16} $ GEV。但是，诸如弹跳宇宙学之类的替代模型允许$ t _ {\ mathrm {max}} $接近$ t _ {\ mathrm {planck}} $。在我们正在考虑的能量尺度上，额外的颗粒数量自然出现在额外尺寸的模型中。
Gravitational waves (GWs) are produced by colliding particles through the gravitational analogue of electromagnetic bremsstrahlung. We calculate the contribution of free-free emission in the radiation-dominated Universe to the stochastic GW background. We find that the energy density of the resulting GW radiation is heavily dependent on the number of elementary particles, $N_{\mathrm{tot}}$, and the maximum initial temperature, $T_{\mathrm{max}}$. We rule out $N_{\mathrm{tot}}\gtrsim N_{\mathrm{SM}}$ for $T_{\mathrm{max}}\sim T_{\mathrm{Planck}}\approx10^{19}$ GeV and $N_{\mathrm{tot}}\gtrsim10^{13}\times N_{\mathrm{SM}}$ for $T_{\mathrm{max}}\sim10^{16}$ GeV, where $N_{\mathrm{SM}}$ is the number of particles in the Standard Model. In the case of inflation, existing cosmological data constrain $T_{\mathrm{max}}\lesssim10^{16}$ GeV. However, alternative models to inflation such as bouncing cosmologies allow for $T_{\mathrm{max}}$ near $T_{\mathrm{Planck}}$. At the energy scales we are considering, the extra number of particles arise naturally in models of extra dimensions.
