42 citations · 290 across the 27 of their papers we have counts for
29 papers
Stochastic Inflation with Interacting Noises
Amin Nassiri-Rad, Haidar Sheikhahmadi, Hassan Firouzjahi
Stochastic formalism is a powerful tool to calculate the cosmological correlators non-perturbatively. However, it requires the initial data for the amplitude of the noise on t…
RG-Flow Renormalized One-Loop Corrections to the Power Spectrum in USR Inflation
Haidar Sheikhahmadi, Amin Nassiri-Rad
The nature of one-loop corrections to long-wavelength CMB-scale modes in single-field inflation models with an intermediate ultra-slow-roll (USR) phase remains a subject of active…
Remove point-mass concept-remove singularities from GR
Yousef Sobouti, Haidar Sheikhahmadi
Singularities in Newton's gravitation, in general relativity (GR), in Coulomb's law, and elsewhere in classical physics, stem from two ill conceived assumptions: a) there are point…
Vacuum zero point energy of self-interacting quantum fields in dS background
Hassan Firouzjahi, Haidar Sheikhahmadi
We consider self-interacting scalar fields with a conformal coupling in the dS background and study the quantum corrections from bubble loop diagrams. Incorporating the perturbativ…
Kerr black hole in presence of force-free magnetic field
Haidar Sheikhahmadi
We extend the study of force-free magnetospheres from non-rotating to rotating black holes \cite{Sheikhahmadi} and investigate the influence of a force-free magnetic field on the g…
Black hole solutions to Einstein-Bel-Robinson gravity
S. N. Sajadi, Robert B. Mann, H. Sheikhahmadi +1
In this paper, we study the physical properties of black holes in the framework of the recently proposed Einstien-Bel-Robinson gravity. We show that interestingly the theory propag…
Vacuum Zero Point Energy and its Statistical Correlations in dS Background
Hassan Firouzjahi, Haidar Sheikhahmadi
We study the vacuum zero point energy associated to a scalar field with an arbitrary mass and conformal coupling in a dS background. Employing dimensional regularization scheme, we…
Astrophysical and electromagnetic emissivity properties of black holes surrounded by a quintessence type exotic fluid in the Scalar-Vector-Tensor Modified Gravity
Haidar Sheikhahmadi, Saheb Soroushfar, S. N. Sajadi +1
The astrophysical consequences of the presence of a quintessence scalar field on the evolution of the horizon and on the accretion disk surrounding a static black hole, in the Scal…
Observational constraints on the interacting dark energy - dark matter (IDM) cosmological models
T. Harko, K. Asadi, H. Moshafi +1
Particle creation (or annihilation) mechanisms, described by either quantum field theoretical models, or by the thermodynamics of irreversible processes, play an important role in…
Schwarzschild black hole perturbed by a force-free magnetic field
Haidar Sheikhahmadi
We envisage a black hole perturbed by a force-free magnetic field (FFMF) outside and attempt to determine its structure. We suppose the metric that describes this black hole is of…
On the origin of the holographic universe
Haidar Sheikhahmadi
In this work, we reexamine the holographic dark energy concept proposed already for cosmological applications. By considering, more precisely, the bounds on the entropy arising fro…
Thermodynamic geometry of static and rotating regular black holes in conformal massive gravity
Saheb Soroushfar, Reza Saffari, Amare Abebe +1
A version of massive gravity, namely conformal massive gravity, is employed to study the behavior of thermodynamic geometry for both the static and the rotating regular black holes…
Warm inflation with non-comoving scalar field and radiation fluid
Tiberiu Harko, Haidar Sheikhahmadi
We consider a warm inflationary scenario in which the two dominant matter components present in the early Universe, the scalar field, and the radiation fluid, evolve with different…
Inflation in String Field Theory
Haidar Sheikhahmadi, Mir Faizal, Ali Aghamohammadi +2
In this paper, we analyze the inflationary cosmology using string field theory. This is done by using the zero level contribution from string field theory, which is a non-local tac…
Irreversible thermodynamical description of warm inflationary cosmological models
Tiberiu Harko, Haidar Sheikhahmadi
We investigate the interaction between scalar fields and radiation in the framework of warm inflationary models by using the irreversible thermodynamics of open systems with matter…
An exact solution for a force-free field electrodynamics accretion disk surrounding a perturbed charged black hole
Haidar Sheikhahmadi
Recently the first real image of the supermassive black hole at the heart of the galaxy M87 successfully has been captured. To explain the behavior of both the observed powerful je…
Warm Tachyon Inflation and Swampland Criteria
Abolhassan Mohammadi, Tayeb Golanbari, Haidar Sheikhahmadi +4
The scenario of two components warm tachyon inflation is considered where the tachyon field plays the role of inflaton and drives inflation. During inflation, the tachyon scalar fi…
Constraining chameleon field driven warm inflation with Planck 2018 data
Haidar Sheikhahmadi, Abolhassan Mohammadi, Ali Aghamohammadi +5
We investigate warm inflationary scenario in which the accelerated expansion of the early Universe is driven by chameleon-like scalar fields. Due to the non-minimal coupling betwee…
Schwinger-Keldysh mechanism in extended quasi single field inflation
Haidar Sheikhahmadi
We study an extension of quasi-single field model of inflation containing multiple semi-heavy isocurvaton fields using the Schwinger-Keldysh mechanism. We calculate the amplitudes…
Non-canonical scalar field in low anisotropy universe with intermediate inflation
Mahdeyeh Naderi, Ali Aghamohammadi, Abdollah Refaei +1
The behaviour of a non-canonical scalar field within an anisotropic Bianchi type I, spatially homogeneous, Universe in the framework of the intermediate inflation will be studied.…
Constraints on warm power-law inflation in light of Planck results
Zahra Ghadiri, Abdollah Refaei, Ali Aghamohammadi +1
The constraints on a general form of the power-law potential and the dissipation coefficient in the framework of warm single field inflation imposed by Planck data will be investig…
Constant-roll approach to non-canonical inflation
Abolhassan Mohammadi, Khaled Saaidi, Haidar Sheikhahmadi
The scenario of constant-roll inflation is studied where the inflaton is a scalar field with modified kinetic term, known as non-canonical scalar field. This modification leads to…
Comments on Cosmic evolution in Brans-Dicke chameleon cosmology
Haidar Sheikhahmadi
The authors of Ref. \cite{1-2}, investigated cosmic evolution in an external interacting model of scalar tensor gravity namely Brans Dicke chameleon scenario. The procedure of this…
Hamilton-Jacobi formalism for inflation with non-minimal derivative coupling
Haidar Sheikhahmadi, Emmanuel N. Saridakis, Ali Aghamohammadi +1
In inflation with nonminimal derivative coupling there is not a conformal transformation to the Einstein frame where calculations are straightforward, and thus in order to extract…