15 citations · 89 across the 11 of their papers we have counts for
11 papers
`Hidden' symmetry of linearized gravity in de Sitter space
Hamed Pejhan, Surena Rahbardehghan, Mohammad Enayati +2
We demonstrate that the linearized Einstein gravity in de Sitter (dS) spacetime besides the evident symmetries also possesses the additional (local) symmetry $h_{μν}\rightarrow h_{…
A small non-vanishing cosmological constant from the Krein-Gupta-Bleuler vacuum
Hamed Pejhan, Kazuharu Bamba, Mohammad Enayati +1
We point out a potential relevance between the Krein-Gupta-Bleuler (KGB) vacuum leading to a fully covariant quantum field theory for gravity in de Sitter (dS) spacetime and the ob…
"Massless" spin-2 field in de Sitter space
Hamed Pejhan, Kazuharu Bamba, Surena Rahbardehghan +1
In this paper, admitting a de Sitter (dS)-invariant vacuum in an indefinite inner product space, we present a Gupta-Bleuler type setting for causal and full dS-covariant quantizati…
Vacuum states for gravitons field in de Sitter space
Kazuharu Bamba, Surena Rahbardehghan, Hamed Pejhan
In this paper, considering the linearized Einstein equation with a two-parameter family of linear covariant gauges in de Sitter spacetime, we examine possible vacuum states for the…
On the graviton two-point function and its infrared behavior in de Sitter spacetime
Surena Rahbardehghan, Hamed Pejhan
In our previous paper (Phys. Rev. D 94, 104030 (2016)), inspired by the work of Allen and Turyn (Nucl. Phys. B 292, 813 (1987)), we expressed the graviton two-point function in ter…
Covariant and infrared-free graviton two-point function in de Sitter spacetime II
Hamed Pejhan, Surena Rahbardehghan
The solution to the linearized Einstein equation in de Sitter (dS) spacetime and the corresponding two-point function are explicitly written down in a gauge with two parameters `$a…
Casimir energy-momentum tensor for a quantized bulk scalar field in the geometry of two curved branes on Friedmann-Robertson-Walker background
Hamed Pejhan, Surena Rahbardehghan
In a previous work [S. Rahbardehghan et al. in Phys. Lett. B 750, 627 (2015)], we considered a simple brane-world model; a single -dimensional brane embedded in a -dimensiona…
Covariant and infrared-free graviton two-point function in de Sitter spacetime
Hamed Pejhan, Surena Rahbardehghan
In this paper, the two-point function of linearized gravitons on de Sitter (dS) space is presented. Technically, respecting the dS ambient space notation, the field equation is giv…
Examining a covariant and renormalizable quantum field theory in de Sitter space by studying "black hole radiation"
Hamed Pejhan, Surena Rahbardehghan
Respecting that any consistent quantum field theory in curved space-time must include black hole radiation, in this paper, we examine the Krein-Gupta-Bleuler (KGB) formalism as an…
The Krein-Gupta-Bleuler Quantization in de Sitter Space-time; Casimir Energy-Momentum Tensor for a Curved Brane
S. Rahbardehghan, H. Pejhan
In this paper, vacuum expectation value (VEV) of the energy-momentum tensor for a conformally coupled scalar field in de Sitter space-time is investigated through the Krein-Gupta-B…
A Group Theoretical Approach to Graviton Two-Point Function
S. Rahbardehghan, H. Pejhan, M. Elmizadeh
Respecting the group theoretical approach, it is debated that the theory of linear conformal gravity should be formulated through a tensor field of rank-3 and mixed symmetry \cite{…