论文标题
诱导重力波作为QCD相变时声速的宇宙学探测
Induced gravitational waves as a cosmological probe of the sound speed during the QCD phase transition
论文作者
论文摘要
已知粒子物理学的标准模型很有趣。然而，尚未完全理解它们以相变（PT）为代表的丰富现象，包括存在未知黑暗部门的可能性。在这封信中，我们通过使用宇宙的引力波（GWS）来研究状态参数$ w $的方程和声速$ c _ {\ rm s} $。尽管GW的传播本身对$ c _ {\ rm s} $不敏感，但声音速度值会影响原始密度（或标量曲率）扰动的动态，而其Hixon Rectry的诱导GW可以是间接的probe probe probe probe probe probe cope $ w $ and $ c _ c _ {\ rm s} $。我们在数值上揭示了预测诱导的GW的混凝土光谱，其中有两个简单的标量扰动光谱示例：单色和标尺不变的光谱。在单色情况下，我们看到诱导的GW的共振扩增和取消量表取决于$ c _ {\ rm s} $值分别在不同时间。比例不变的情况给出了更逼真的频谱，其特定形状将与观察结果进行比较。特别是，QCD相变的频率范围对应于脉冲星定时阵列（PTA）观测值的频率范围。如果原始标量功率的幅度在$ 10^{ - 4} \ Lessima_ζ\ Lessim10^{ - 2} $的范围内，则诱导的GW与当前的观察性约束一致，并且在平方公里阵列中的未来观察中可检测到。 futhermore Nanograv对随机GWS的最新检测12.5 yr Analysis〜[1]可以通过诱导的GW解释，如果$ a_Tim \ sim \ sim \ sqrt {7} \ times10^{ - 3} $。
The standard model of particle physics is known to be intriguingly successful. However their rich phenomena represented by the phase transitions (PTs) have not been completely understood yet, including the possibility of the existence of unknown dark sectors. In this Letter, we investigate the measurement of the equation of state parameter $w$ and the sound speed $c_{\rm s}$ of the PT plasma with use of the gravitational waves (GWs) of the universe. Though the propagation of GW is insensitive to $c_{\rm s}$ in itself, the sound speed value affects the dynamics of primordial density (or scalar curvature) perturbations and the induced GW by their horizon reentry can then be an indirect probe both $w$ and $c_{\rm s}$. We numerically reveal the concrete spectrum of the predicted induced GW with two simple examples of the scalar perturbation spectrum: the monochromatic and scale-invariant spectra. In the monochromatic case, we see that the resonant amplification and cancellation scales of the induced GW depend on the $c_{\rm s}$ values at different time respectively. The scale-invariant case gives a more realistic spectrum and its specific shape will be compared with observations. In particular, the QCD phase transition corresponds with the frequency range of the pulsar timing array (PTA) observations. If the amplitude of primordial scalar power is in the range of $10^{-4}\lesssim A_ζ\lesssim10^{-2}$, the induced GW is consistent with current observational constraints and detectable in the future observation in Square Kilometer Array. Futhermore the recent possible detection of stochastic GWs by NANOGrav 12.5 yr analysis~[1] can be explained by the induced GW if $A_ζ\sim\sqrt{7}\times10^{-3}$.
