论文标题
$ h_0 $张力：$Δg_n$ vs. $δn_ {\ rm eff} $
The $H_0$ tension: $ΔG_N$ vs. $ΔN_{\rm eff}$
论文作者
论文摘要
我们调查了Sh $ _ {0} $ ES 2019和Planck 2018之间$ H_0 $的$4.4σ$张力是否可以通过牛顿早期和晚期宇宙之间的牛顿常数$ g_n $的变化来减轻。这改变了重组之前的哈勃速率，类似于添加$Δn_ {\ rm eff} $额外的相对论自由度。我们在标量调整的重力理论中实现了不同的$ g_n $，并具有非最小耦合$（m^2+βϕ^2）r $。如果标量$ ϕ $从辐射时代开始于初始值$ ϕ_i \ sim 0.5〜m_p $，并且以$β<0 $开始，则在物质辐射平等的时期围绕较晚的物质平等时期，场地向零发生了动态过渡。结果，Sh $ _ {0} $ ES（2019）和Planck 2018+Bao之间的$ H_0 $张力略微降低，例如$Δn_ {\ rm eff} $模型，到3.8 $σ$级别。然后，我们对合并的Planck，Bao和Supernovae（Sh $ _0 $ es and Pantheon）数据集进行拟合。当包括对北顿后（PN）参数的本地约束时，我们发现$ h_0 = 69.08 _ { - 0.71}^{+0.6}〜\ text {km/s/s/mpc} $，而边际改善$δχ^2 \ simeq-3.2 $ $ simeq-3.2 $与$ up cdm相比，为了考虑可以避免局部约束的情况，我们还没有PN限制，并找到$ H_0 = 69.65 _ { - 0.78}^{+0.8}〜\ text {km/s/s/s/mpc} $，并且更重要的改进$ nige Cradivement $ never $ nivement $ nevement $ nevement $ nevement $δχ^2 = -5.4 $ $ 5.4 $ $。为了进行比较，我们发现$δn_ {\ rm eff} $模型给出$ h_0 = 70.08 _ { - 0.95}^{+0.91}〜\ text {km/s/s/s/s/s/s/s/mpc} $和$δχ^2 = -3.4 $，以$ cdm的$ cdm，$ cdm cdm cdm，$ cdm cdm，p.cdm cdm p.cdm， $Δn_ {\ rm eff} = 0.34 _ { - 0.16}^{+0.15} $。总体而言，如果可以实现$ h_0 $张力，我们的$ g_n $模型的性能与$δn_ {\ rm eff} $模型相似，如果可以实现用于删除PN约束的物理机制。
We investigate whether the $4.4σ$ tension on $H_0$ between SH$_{0}$ES 2019 and Planck 2018 can be alleviated by a variation of Newton's constant $G_N$ between the early and the late Universe. This changes the Hubble rate before recombination, similarly to adding $ΔN_{\rm eff}$ extra relativistic degrees of freedom. We implement a varying $G_N$ in a scalar-tensor theory of gravity, with a non-minimal coupling $(M^2+βϕ^2)R$. If the scalar $ϕ$ starts in the radiation era at an initial value $ϕ_I \sim 0.5~M_p$ and with $β<0$, a dynamical transition occurs naturally around the epoch of matter-radiation equality and the field evolves towards zero at late times. As a consequence, the $H_0$ tension between SH$_{0}$ES (2019) and Planck 2018+BAO slightly decreases, as in $ΔN_{\rm eff}$ models, to the 3.8$σ$ level. We then perform a fit to a combined Planck, BAO and supernovae (SH$_0$ES and Pantheon) dataset. When including local constraints on Post-Newtonian (PN) parameters, we find $H_0=69.08_{-0.71}^{+0.6}~\text{km/s/Mpc}$ and a marginal improvement of $Δχ^2\simeq-3.2$ compared to $Λ$CDM, at the cost of 2 extra parameters. In order to take into account scenarios where local constraints could be evaded, we also perform a fit without PN constraints and find $H_0=69.65_{-0.78}^{+0.8}~\text{km/s/Mpc}$ and a more significant improvement $Δχ^2=-5.4$ with 2 extra parameters. For comparison, we find that the $ΔN_{\rm eff}$ model gives $H_0=70.08_{-0.95}^{+0.91}~\text{km/s/Mpc}$ and $Δχ^2=-3.4$ at the cost of one extra parameter, which disfavors the $Λ$CDM limit just above 2$σ$, since $ΔN_{\rm eff}=0.34_{-0.16}^{+0.15}$. Overall, our varying $G_N$ model performs similarly to the $ΔN_{\rm eff}$ model in respect to the $H_0$ tension, if a physical mechanism to remove PN constraints can be implemented.
