Article
Physics, Particles & Fields
Arko Bhaumik, Soumitra Sengupta
Summary: We generalize nested multiply warped braneworld models by incorporating non-zero brane curvature caused by an effective cosmological constant, and study the dependence of scale-clustering and fermion mass hierarchy on the brane cosmological constant and warping parameters in different scenarios. The key results are then extended to arbitrary n-fold nested warped braneworlds.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Physics, Multidisciplinary
Rikpratik Sengupta, Bikash Ch Paul, Mehedi Kalam, Prasenjit Paul, Arkajit Aich
Summary: In this paper, the authors investigate an exotic matter source with a nonlinear equation of state and a minimally coupled scalar field with two different potentials that result in a closed inflationary emergent universe in a relativistic context. The study is conducted in the framework of Randall-Sundrum braneworld and effective Loop quantum cosmology, considering vanishing spatial curvature and no effective cosmological constant term. The results show that the initial singularity can be averted in almost all the cases, and the inflationary scenario is found to be improved compared to the standard relativistic context. The authors also discover bouncing and cyclic universes from their analysis in some cases, indicating the possibility of avoiding the initial singularity by appropriate mechanisms.
EUROPEAN PHYSICAL JOURNAL PLUS
(2023)
Article
Physics, Particles & Fields
A. S. Agrawal, B. Mishra, P. K. Agrawal
Summary: In this paper, we have presented the matter bounce scenario of the Universe within an extended symmetric teleparallel gravity, known as the f (Q) gravity. By incorporating the bouncing scenario and loop quantum cosmology, we have determined the form of the function f (Q) within the Friedmann-Lemaitre-Robertson Walker space-time. Considering a background cosmology dominated by dust fluid, we have expressed the e-folding parameter that includes the nonmetricity term. Due to the invalidity of the slow roll criterion in the bouncing context, we have utilized a conformal equivalence between f (Q) and scalar-tensor model to apply the bottom-up reconstruction technique. The dynamics of the model have been examined through phase space analysis, yielding both stable and unstable nodes. Furthermore, stability analysis has been performed on the first-order scalar perturbation of the Hubble parameter and matter energy density to confirm the stability of the model.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Physics, Particles & Fields
Andrzej Gozdz, Aleksandra Pedrak, Wlodzimierz Piechocki
Summary: We quantize the solution to the BKL scenario using integral quantization method, which smears the gravitational singularity and prevents its localization in the configuration space. The relative quantum perturbations grow as the system evolves towards the gravitational singularity, amplifying the deterministic classical chaos. Our results suggest that the generic singularity of general relativity can be avoided at a quantum level, supporting the expectation of quantum gravity being a regular theory.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Astronomy & Astrophysics
Indrani Banerjee, Tanmoy Paul, Soumitra SenGupta
Summary: This study investigates how the interaction between the radion potential and kinetic term in a warped braneworld scenario leads to the transition of the universe from a contracting to an expanding phase during a non-singular bounce. The analysis shows that the predicted primordial observables are consistent with the constraints reported by the Planck satellite.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Chia -Min Lin
Summary: In this paper, we revisit D-term inflation and provide bounds on the cosmic string tension using gravitational wave observations. We also consider the possible deviation of the spectral index compared with the ΛCDM model in light of prerecombination resolutions of the Hubble tension. Our study shows that D-term inflation requires very small coupling constants under these constraints, and we demonstrate that natural coupling constants (g = A = 0.1) can be achieved in the case of D-term inflation on the brane.
Article
Physics, Particles & Fields
Arko Bhaumik, Soumitra SenGupta
Summary: The study demonstrates that it is possible to stabilize two distinct moduli simultaneously in a model with nested warping, by introducing an effective 4D moduli potential. This mechanism offers a resolution to the hierarchy problem in the Standard Model.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Astronomy & Astrophysics
Sadaf Maqsood, Abdul Jawad
Summary: Studied two Chaplygin gas models embedded in the Randall-Sundrum braneworld and derived the de Sitter constraint using the covariant entropy bound. Showed that the models are compatible with swampland criteria in the context of warm inflation dynamics, and investigated the constraint on the warm inflation parameter.
MODERN PHYSICS LETTERS A
(2022)
Article
Astronomy & Astrophysics
Qihong Huang, Kaituo Zhang, He Huang, Bing Xu, Feiquan Tu
Summary: The emergent universe provides an alternative to the Big Bang singularity by proposing that the universe originates from a stable Einstein static universe. This concept suggests that relics from the Einstein static universe may be detected in the CMB power spectrum. In this study, the stability conditions for the Einstein static universe in general relativity with k-essence are analyzed in terms of both scalar and tensor perturbations. Additionally, the emergent universe can be successfully realized by introducing a scalar potential and an equation of state parameter.
Article
Astronomy & Astrophysics
Rikpratik Sengupta, Shounak Ghosh, B. C. Paul, M. Kalam
Summary: A non-singular emergent universe scenario requires a generalized equation of state (EoS) to describe the composition of exotic matter, dark energy, and cosmological dust matter. This study investigates the possibility of static and traversable Lorentzian wormholes in such a scenario, which violate the null energy condition (NEC) at the throat. The obtained wormhole shape function satisfies the criteria for formation and remains stable, with the estimated EU parameters in agreement with observational data.
CLASSICAL AND QUANTUM GRAVITY
(2023)
Article
Astronomy & Astrophysics
Bastian Diaz Saez, Kilian Mohling, Dominik Stockinger
Summary: The model consists of two interacting real singlet scalars, with only one of them coupled to the Higgs, presenting a minimal assisted-freeze-out framework. While both scalars contribute to dark matter relic density, only one takes part in elastic scattering with nuclei, potentially evading XENON1T constraints. The model is viable in the Higgs resonance region and for scalar singlet masses of hundreds of GeV, but becomes highly constrained at high energies.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Oleksii Sokoliuk, Alexander Baransky, P. K. Sahoo
Summary: In this study, we investigate isotropic static spherically symmetric gravastars without charge under the framework of braneworld gravity. We use the Kuchowicz metric potential and derive the Kuchowicz free parameters using the junction conditions. We assume the interior is filled with a Dark Energy-like fluid and the shell is composed of ultrarelativistic stiff fluid. The study explores various physical aspects of gravastars.
Article
Astronomy & Astrophysics
Payel Sarkar, Prasanta Kumar Das
Summary: In this study, we investigated the bouncing universe scenario in the case of modified gravity represented by f(R,T) = R + 2 lambda T, where R is the Ricci scalar and T is the trace of energy momentum tensor. Two different types of scale factors were considered, which were non-zero at t = 0 (the bounce point). The initial non-vanishing values of the scale factors resolved the singularity problem. The behaviors of the Hubble parameter H and the deceleration parameter q were examined for two different models corresponding to the two scale factors. Violation of energy conditions was observed, and both models were highly unstable at the bounce point, but the perturbation decayed rapidly away from the bounce and became stable at late times.
PHYSICS OF THE DARK UNIVERSE
(2023)
Article
Astronomy & Astrophysics
Raja Solanki, Avik De, P. K. Sahoo
Summary: In this study, the fundamental nature and evolution mechanism of dark energy in theoretical physics are explored using modified symmetric teleparallel gravity. The behavior of dark energy with different model parameters is analyzed, and it is found that it can exhibit quintessence or phantom scenario-like behavior. The study suggests that the geometrical generalization of general relativity can be a viable candidate for explaining the origin of dark energy.
PHYSICS OF THE DARK UNIVERSE
(2022)
Article
Astronomy & Astrophysics
Bikram Ghosh, Saugata Mitra
Summary: This paper examines the impact of energy density and shape function on wormhole solutions using field equations of braneworld gravity theory, considering isotropic and anisotropic scenarios. Different redshift functions and shape functions are explored, and it is found that in some cases all energy conditions are satisfied near the wormhole throat, while in other cases all energy conditions are met except for the strong energy condition.
MODERN PHYSICS LETTERS A
(2021)
Article
Physics, Mathematical
Fateme Gholami, Farhad Darabi, Ali Haji-Badali
INTERNATIONAL JOURNAL OF GEOMETRIC METHODS IN MODERN PHYSICS
(2017)
Article
Astronomy & Astrophysics
M. R. Setare, F. Felegary, F. Darabi
INTERNATIONAL JOURNAL OF MODERN PHYSICS D
(2017)
Article
Physics, Particles & Fields
M. Mousavi, F. Darabi
Article
Physics, Particles & Fields
H. Hadi, Y. Heydarzade, M. Hashemi, F. Darabi
EUROPEAN PHYSICAL JOURNAL C
(2018)
Article
Physics, Particles & Fields
F. Darabi, H. Moradpour, I. Licata, Y. Heydarzade, C. Corda
EUROPEAN PHYSICAL JOURNAL C
(2018)
Article
Physics, Particles & Fields
Y. Heydarzade, F. Darabi
EUROPEAN PHYSICAL JOURNAL C
(2018)
Article
Physics, Particles & Fields
Y. Heydarzade, F. Darabi
EUROPEAN PHYSICAL JOURNAL C
(2018)
Article
Physics, Mathematical
F. Gholami, A. Haji-Badali, F. Darabi
INTERNATIONAL JOURNAL OF GEOMETRIC METHODS IN MODERN PHYSICS
(2018)
Article
Physics, Mathematical
F. Darabi, K. Atazadeh
INTERNATIONAL JOURNAL OF GEOMETRIC METHODS IN MODERN PHYSICS
(2018)
Article
Astronomy & Astrophysics
F. Felegary, F. Darabi, M. R. Setare
INTERNATIONAL JOURNAL OF MODERN PHYSICS D
(2018)
Article
Astronomy & Astrophysics
Yaghoub Heydarzade, Prabir Rudra, Behnam Pourhassan, Mir Faizal, Ahmed Farag Ali, Farhad Darabi
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2018)
Article
Astronomy & Astrophysics
Y. Heydarzade, H. Hadi, C. Corda, F. Darabi
Article
Physics, Multidisciplinary
F. Darabi, K. Atazadeh, Y. Heydarzade
EUROPEAN PHYSICAL JOURNAL PLUS
(2018)
Article
Physics, Particles & Fields
R. Shojaee, K. Nozari, F. Darabi
ADVANCES IN HIGH ENERGY PHYSICS
(2018)
Article
Astronomy & Astrophysics
F. Naderi, A. Rezaei-Aghdam, F. Darabi