We study an extension of symmetric teleparallel gravity i.e. Weyl-type $f(Q,T)$ gravity and the divergence-free parametrization of the deceleration parameter $q(z) = q_{0}+q_{1}\frac{z(1+z)}{1+z^2}$ ($q_{0}$ and $q_{1}$ are free constants) to explore the evolution of the universe. By considering the above parametric form of $q$, we derive the Hubble solution and further impose it in the Friedmann equations of Weyl-type $f(Q, T)$ gravity. To see whether this model can challenge the $Λ$CDM limits, we computed the constraints on the model parameters using the Bayesian analysis for the Observational Hubble data ($OHD$) and the Pantheon sample ($SNe\,Ia$). Furthermore, the deceleration parameter depicts the accelerating behavior of the universe with the present value $q_0$ and the transition redshift $z_t$ (at which the expansion transits from deceleration to acceleration) with $1-σ$ and $2-σ$ confidence level. We also examine the evolution of the energy density, pressure, and effective equation of state parameters. Finally, we demonstrate that the divergence-free parametric form of the deceleration parameter is consistent with the Weyl-type $f(Q,T)$ gravity.
One-loop divergences in 7D Einstein and 6D Conformal Gravities
本文的目的是揭示7 D爱因斯坦引力和6D共形引力的单圈发散之间的惊人等价性。6D共形引力的6D逐点Weyl不变量的特定组合对应于Branson的Q曲率，并且可以单独用Ricci张量及其协变导数来表示。这个作用的二次度规涨落，6D Weyl引力子，被赋予了一个六阶动力学算子，该算子恰好在6D爱因斯坦背景下分解为三个移位的Lichnerowicz Laplacian的乘积。我们利用这一特点，使用标准的热核技术，并在一个去的UV对数发散的理论，在这种情况下，包含四个外尔异常系数。在一个看似无关的计算中，我们确定了在一个特定的7 D Poincaré-Einstein背景中7 D Einstein引力的单圈IR对数发散，该背景是渐近双曲的，并且在其共形无穷远处或边界处具有上述6D Einstein流形。我们显示了完全等效的两个计算，作为一个副产品的IR/UV连接在AdS/CFT对应，并以这种方式，在爱因斯坦和高导数引力的时间-历史悠久的单圈计算采取一个有趣的新的转折。
Energy extraction processes and thermodynamics in rotating Weyl conformal black holes
Samarkand State University（撒马尔罕国立大学）；Gulistan State University（古利斯坦国立大学）；Khazar University（哈萨尔大学）；Kimyo International University in Tashkent（塔什干化学国际大学）；University of Tashkent for Applied Sciences（塔什干应用科学大学）；Harbin Institute of Technology（哈尔滨工业大学）；National Research University TIIAME（TIIAME国立研究大学）；National University of Uzbekistan（乌兹别克斯坦国立大学）；Zhejiang Normal University（浙江师范大学）
