AI 中文总结
本研究提出一种六参数teleparallel引力模型，其几何扇区产生变号暗能量，自然缓解$H_0$张力，但拟合优度略逊于$\Lambda$CDM。
AI 中文摘要
我们研究了扩展指数红外f(T) teleparallel引力的一种特殊情况，其中几何扇区自然地产生一个有效的暗能量密度，该密度从过去的负值演化为晚期的正值。这种行为可能由观测结果所激发，为修正引力中几何的、变号的暗能量情景提供了令人信服的动机。我们证明了当前模型的参数空间仅包含六个参数，与$\Lambda$CDM类似。使用Planck、DESI和Ia型超新星数据进行的马尔可夫链蒙特卡洛（MCMC）分析给出了一个约束良好的跃迁红移$z_{\rm tr} \gtrsim 1.62$，伴随着有效状态方程向幻影区域（$w < -1$）的跃迁，对于$z < z_{\rm tr}$。由于有效暗能量来源于修正的几何自由度，因此不会出现不稳定性或能量条件的违反。该模型自然地解释了$H_0$张力，其中Planck+DESI数据组合给出$H_0 = 72.13 \pm 0.28 \text{ km s}^{-1} \text{ Mpc}^{-1}$，与局部测量相比，比$\Lambda$CDM给出的$H_0 = 68.46 \pm 0.30 \text{ km s}^{-1} \text{ Mpc}^{-1}$更一致。然而，在最佳拟合参数的$\chi^2$值方面，该模型与$\Lambda$CDM相比处于劣势。我们讨论了这一结果以及与其他CMB-BAO张力相关的问题。
英文摘要
We investigate a particular case of the extended exponential infrared f(T) teleparallel gravity, in which the geometric sector naturally produces an effective dark-energy density that evolves from negative values in the past to positive values at late times. This behaviour could be motivated by observational results providing a compelling motivation for a geometric, sign-changing dark-energy scenario within modified gravity. We demonstrate that the parameter space of the present model contains only six parameters similar to $Λ$CDM. A Markov Chain Monte Carlo (MCMC) analysis using Planck, DESI, and Type Ia supernova data yields a well-constrained transition redshift of $z_{\rm tr} \gtrsim 1.62$, accompanied by a transition in the effective equation of state to the phantom regime ($w < -1$) for $z < z_{\rm tr}$. Since the effective dark energy originates from modified geometric degrees of freedom, no instabilities or violations of energy conditions arise. The model naturally accounts for the $H_0$ tension, where Planck+DESI data combination gives $H_0 = 72.13 \pm 0.28 \text{ km s}^{-1} \text{ Mpc}^{-1}$ in a better agreement with local measurements than $Λ$CDM which gives $H_0 = 68.46 \pm 0.30 \text{ km s}^{-1} \text{ Mpc}^{-1}$. However, the model is disfavored in comparison to $Λ$CDM in terms of the values of $χ^2$ of the bestfit parameters. We discuss the result among other issues related to CMB-BAO tension.
Comments24 pages,15 figures
