标题： 从标量诱导引力波缺失的两圈贡献对原初非高斯性的新限制 显示英文标题

标题： New constraints on primordial non-Gaussianity from missing two-loop contributions of scalar induced gravitational waves

摘要： 我们利用NANOGrav 15年的数据集分析了\acp{SIGW}的能量密度谱，从而限制了原初非高斯参数$f_{\mathrm{NL}}$。首次计算了与局域型原初非高斯性两点关联函数$\langle h^{\lambda,(3)}_{\mathbf{k}} h^{\lambda',(2)}_{\mathbf{k}'} \rangle$相对应的十七个缺失的二阶圈图，这些圈图与$f_{\mathrm{NL}}A_{\zeta}^3$成正比。\acp{SIGW}的总能量密度谱会因这些二阶圈图而显著被抑制。 如果在\ac{PTA}实验中观测到的\acp{SGWB}被\acp{SIGW}主导，那么基于 NANOGrav 15年数据集，参数区间$f_{\mathrm{NL}}\in [-5,-1]$显著被排除。考虑到\acp{PBH}的丰度以及宇宙扰动展开的收敛性，我们发现$f_{\mathrm{NL}}$可能的唯一参数范围是$-1\le f_{\mathrm{NL}}< 0$。 显示英文摘要

摘要： We analyze the energy density spectrum of \acp{SIGW} using the NANOGrav 15-year data set, thereby constraining the primordial non-Gaussian parameter $f_{\mathrm{NL}}$. For the first time, we calculate the seventeen missing two-loop diagrams proportional to $f_{\mathrm{NL}}A_{\zeta}^3$ that correspond to the two-point correlation function $\langle h^{\lambda,(3)}_{\mathbf{k}} h^{\lambda',(2)}_{\mathbf{k}'} \rangle$ for local-type primordial non-Gaussianity. The total energy density spectrum of \acp{SIGW} can be significantly suppressed by these two-loop diagrams. If \acp{SIGW} dominate the \acp{SGWB} observed in \ac{PTA} experiments, the parameter interval $f_{\mathrm{NL}}\in [-5,-1]$ is notably excluded based on NANOGrav 15-year data set. After taking into account abundance of \acp{PBH} and the convergence of the cosmological perturbation expansion, we find that the only possible parameter range for $f_{\mathrm{NL}}$ might be $-1\le f_{\mathrm{NL}}< 0$.