具有观测约束的f（Q，T）引力中天宇宙学模型
Transit cosmological models with observational constraints in f(Q, T) gravity
摘要：
这个宇宙学模型是对徐{ \it et al.}最近提出的修正的$f(Q,T)$引力理论的研究。（Eur. J. C { \bf 79}，708（2019））。在这个引力理论中，作用量包含一个任意函数$f(Q,T)$，其中$Q$是非度规性的，$T$是物质流体的能量动量张量的迹。在我们的研究中，我们把$Q$中的二次函数$f(Q,T)$和$T$中的线性函数$f(Q,T)$取为$f(Q,T)=αQ+βQ^{2}+γT$，其中$α$，$β$和$γ$是模型参数，由$f(R,T)$引力驱动。本文利用能量守恒定律的约束，得到了Friedmann-Lemaitre-Robertson-walker（FLRW）宇宙中的各种宇宙学参数，即哈勃参数$H$，减速参数$q$等，它们是用标度因子表示的，也是用红移$z$表示的。对于观测约束的模式，我们已经获得了最佳拟合值的模型参数使用现有的数据集，如哈勃数据集$H(z)$，联合光变曲线分析（JLA）数据集和联盟$2.1$汇编的SNe Ia数据集，通过应用$R^{2}$ -测试公式。计算了各种观测参数$H_{0}$、$q_{0}$、$t_{0}$和状态探测器参数$(s,r)$的当前值，这些值与标准宇宙学模型非常接近。此外，我们已经观察到，减速参数$q(z)$显示签名翻转（过渡）点的范围内$0.423\leq z_{t}\leq0.668$，通过它改变其相位从减速到加速膨胀的宇宙状态方程（EoS）$-1.071\leqω-0.96$为$0\leq z\leq3$。
英文摘要：
This cosmological model is a study of modified $f(Q,T)$ theory of gravity which was recently proposed by Xu {\it et al.} (Eur. Phys. J. C {\bf 79}, 708 (2019)). In this theory of gravity, the action contains an arbitrary function $f(Q,T)$ where $Q$ is non-metricity and $T$ is the trace of energy-momentum tensor for matter fluid. In our research, we have taken the function $f(Q,T)$ quadratic in $Q$ and linear in $T$ as $f(Q,T)=αQ+βQ^{2}+γT$ where $α$, $β$ and $γ$ are model parameters, motivated by $f(R,T)$ gravity. We have obtained the various cosmological parameters in Friedmann-Lemaitre-Robertson-walker (FLRW) Universe viz. Hubble parameter $H$, deceleration parameter $q$ etc. in terms of scale-factor as well as in terms of redshift $z$ by constraining energy-conservation law. For observational constraints on the model, we have obtained the best-fit values of model parameters using the available data sets like Hubble data sets $H(z)$, Joint Light Curve Analysis (JLA) data sets and union $2.1$ compilation of SNe Ia data sets by applying $R^{2}$-test formula. We have calculated the present values of various observational parameters viz. $H_{0}$, $q_{0}$, $t_{0}$ and statefinder parameters $(s,r)$, these values are very close to the standard cosmological models. Also, we have observed that the deceleration parameter $q(z)$ shows signature-flipping (transition) point within the range $0.423\leq z_{t}\leq0.668$ through which it changes its phase from decelerated to accelerated expanding universe with equation of state (EoS) $-1.071\leqω-0.96$ for $0\leq z\leq3$.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
