Journal of Holography Applications in Physics
Volume:2 Issue: 1, Winter 2022

In this work we have investigated the inflation mechanism driven by the Barrow Holographic dark energy (BHDE) in the early universe. BHDE is based on the Barrow relation for horizon entropy, which in turn is inspired from the shape of the COVID-19 virus. It was shown by Barrow that the quantum gravitational effects may instigate complex fractal features in the structure of a black hole. Since the length scale during the inflation is expected to be small, the energy density obtained from the application of the holographic principle in the early universe will be large enough to support the inflationary scenario. Using the Granda-Oliveros IR cut-off we have studied the inflationary scenario with the universe filled with BHDE. Various analytic solutions for the model were found out including the slow-roll parameters, scalar spectral index and tensor-to-scalar ratio. Since inflation is generally attributed to the presence of scalar fields, we have explored a correspondence between BHDE and scalar field models. Both canonical scalar field and the Tachyonic scalar field have been considered for this purpose. The evolution of the potential generated from the fields are plotted and found to be consistent with the observations. From the work we see that BHDE can be a model of dark energy that can successfully drive the early time inflation.

In this paper, we are going to investigate a new perspective of the two-field inflationmodel with respect to the swampland dS conjecture. At the first step, we study the two-fieldsinflation model, and apply the swampland conjecture to our model. Then, we calculate somecosmological parameters such as scalar spectrum index, tensor-to-scalar ratio, and compare ourresults with the recent observational data. Also, we give numerical analysis to show agreementwith observational data.

We present the thermodynamics of a charged and rotating BTZ black holes here. In particular, we derive expressions for various macroscopic thermal quantities such as entropy, Hawking temperature, Helmholtz free energy, internal energy, enthalpy, Gibbs free energy, and specific heat.To study the effects of small statistical thermal fluctuations around the equilibrium on thermodynamics, we calculated the leading-order corrections to the variousthermodynamical potentials of charged and rotating BTZ black hole and do comparative analysis for the fixed values of charge and angular momentum.

We study the transmission probability of Dirac fermions in graphene scattered by a triangulardouble barrier potential in the presence of an external magnetic field. Our system made of twotriangular potential barrier regions separated by a well region characterized by an energy gapGp . Solving our Dirac-like equation and matching the solutions at the boundaries we express ourtransmission and reflection coefficients in terms of transfer matrix. We show in particular that thetransmission exhibits oscillation resonances that are manifestation of the Klein tunneling effect.

In this work, we consider a static spherically symmetric charged regular black hole to investigate arbitrarily high centre of mass energy near the horizon with particle collision for extremal case in the equatorial plane ($theta=pi/2$). Here we also study circular geodesics and find the ISCO and MBCO redii. We analysis the two neutral particles collision with same masses and different masses. Also we analyze the particle collision with massless photon and photon-photon collision near the horizon of this regular black hole to calculate centre of mass energy.

Topological order is a new type order that beyond Landau's symmetry breaking theory. It has some interesting properties, such as producing quasi-particles with fractional quantum numbers and fractional/Fermi statistics, robust gapless boundary modes and emergent gauge excitations. In this essay, we will show that the quantum gravity in AdS3 spacetime can also have topological orders. Actually the theory has all the three features that define the topological order. We conjecture that quantum gravity in four dimension can also have topological orders.