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H. Saiedi

Publications and source records attributed to H. Saiedi.

4 recordsLinked to original sources
arXiv2018

Energy Conditions in Palatini Approach to Modified $f(R)$ Gravity

In this paper, we review modified $f(R)$ theories of gravity in Palatini formalism. In this framework, , we use the Raychaudhuri's equation along with the requirement that the gravity is attractive, which holds for any geometrical theory of gravity to discuss the energy conditions. Then, to derive these conditions, we obtain an expression for effective pressure and energy density by considering FLRW metric. Energy conditions derived in Palatini version of $f(R)$ Gravity differ from those derived in GR. We will see that the WEC (weak energy condition) derived in Palatini formalism has exactly the same expression in its metric approach.

gr-qc↗
arXiv2014

Thermodynamics of Evolving Lorentzian Wormholes at Apparent Horizon in $f(R)$ Theory of Gravity

In the context of modified $f(R)$ gravity, we attempt to study the thermodynamic properties of the evolving Lorentzian wormholes at the apparent horizon. It is shown that the wormhole can be derived from a particular $f(R)$ model in the radiation background. Moreover, it has been shown that the field equations can be cast to a similar form $dE = TdS + WdV + Td\bar{S}$ at the apparent horizon for the evolving Lorentzian wormhole. Compared to the case of Einstein's general relativity, an additional term $Td\bar{S}$ appears here.

gr-qc↗
arXiv2014

Time-Dependent Wormhole Solutions of $f(R)$ Theory of Gravity and Energy Conditions

In this work, we construct time-dependent wormhole solutions in the context of $f(R)$ theory of gravity. The background matter is considered to be traceless. By considering specific shape function and power-law expansion exact solutions for $f(R)$ are found. The null and the weak energy conditions (NEC and WEC) are checked for wormhole solutions. It is shown that the matter threading the wormhole spacetimes with either accelerated expansion or decelerated expansion satisfies the NEC and WEC.

physics.gen-ph↗