kourosh nozari

We study the non-minimal inflation with both the large field and small field potentials in the context of the new observational data. We analyze the linear and non-linear perturbations to obtain the scalar spectral index, tensor-to-scalar ratio, and nonlinearity parameter. By performing a numerical analysis on the scalar spectral index and tensor-to-scalar ratio, and comparing the results with Planck2018 TT, TE, EE+lowE+lensing+BAO+BK14(18) data, we find that the non-minimal large field inflation is observationally viable if the non-minimal coupling parameter is of the order of $10^{-3}$. The same analysis on the non-minimal small field inflation gives the values for the non-minimal coupling parameter as $10^{-4}$. We also study the non-Gaussian features in both equilateral and orthogonal configurations for large and small field potentials and find small values for these amplitudes, consistent with Planck2018 TTT, EEE, TTE and EET data. We show that the absolute values of the non-linearity parameter, $f_{NL}$, is larger in large field inflation than the small field model for both configurations. Also, we obtain more severe constraints on the parameter $p$ in the introduced large field and small field potentials with respect to previously reported constraints.

One of the most promising theories for modified gravity is the Einstein-Gauss-Bonnet (EGB) gravity. In the framework of EGB gravity, we intend to compute the Hawking radiation of a 5-dimensional Hayward black hole with a regular center and with both inner (Cauchy) and outer (event) horizons. On the basis of particles in a dynamical geometry, we provide a brief derivation of Hawking radiation as a tunneling process. The Boltzmann factor of emission at the Hawking temperature is related to the imaginary part of the action for the classically prohibited process.

In this paper, we aim to explore the impact of the Planck scale corrections and the Holographic quintessence on the shadow behavior of non-rotating black holes. To do this, we consider the quantum-corrected Schwarzschild black hole surrounded by the quintessence field inspired by the Kazakov-Solodukhin and the Kiselev ideas, and we call this combination the Kazakov-Solodukhin-Kiselev (KSK) black hole. We conclude that the quintessence field as the candidate of dark energy in the black hole can be interpreted as Holographic quintessence. To find the geodesic equations of the black hole, we employ the Hamilton-Jacobi approach and also, the Carter procedure. We discover that the size of the shadow of this black hole, which depends on its central mass, is also determined by the Planck scale effects and Holographic quintessence.

As generally accepted, consciousness or mind and material brain are closely related to each other; but how? Quantum mechanics is a new pathway to understand the hard problem of consciousness and its relation to the brain. Consciousness has specific properties such as unity, irreducibility, non-locality, etc. The completely different features of classical physics (locality, reducibility, determinacy, etc.) hindered the success of scientists to study consciousness. But quantum mechanics with its features (non-locality, irreducibility, indeterminacy, etc.) gave scientists hope to study consciousness. Several quantum approaches to consciousness have been proposed in recent decades; the most important point about these approaches is that each one has used its own philosophy to determine its viewpoint about the mind’s nature and even its quantum approach. In general, all scientific theories are based on some metaphysical principles which come from the worldview of scientists. In this article four contemporary approaches are discussed: The Eccles-Beck, Stapp, Penrose-Hameroff, and Avicenna-Bohm theories; philosophical and scientific points are highlighted for each of them. Finally, the theory of Top-Down Causation is discussed because we think it can provide a fertile philosophical ground for theories of “mind-brain relation” and “quantum consciousness”.

In this paper, a combination of the braneworld scenario and covariant de Rham-Gabadadze-Tolley (dRGT) massive Gravity theory is proposed. In this setup, the five-dimensional bulk graviton is considered to be massive. The five dimensional nonlinear ghost-free massive gravity theory affects the 3-brane dynamics and the gravitational potential on the brane. Following the solutions with spherical symmetry on the brane, the full field equations together with the generalized Israel-Darmois junction conditions on the brane and their weak field limits are presented in details. Generally, the theory has four Stuckelberg fields along with the components of physical metric. Although analytical solutions of these equations are impossible in general, by considering some simplifying assumptions, two classes of four-dimensional spherically symmetric solutions on the brane with different background Stuckelberg fields are obtained.