Article
Physics, Multidisciplinary
J. Kluson
Summary: We propose an action for the D0-brane anti-D0-brane system with an exact solution corresponding to the marginal tachyon profile defined for arbitrary constant separation of these D-branes. We also find its covariant formulation and generalization to higher dimensional Dp-branes.
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
(2023)
Article
Astronomy & Astrophysics
Chanyong Park
Summary: We investigate the time evolution of entanglement entropy in expanding universes with different matters. Using a braneworld model in an asymptotic AdS space with a uniform p-brane gas, we describe expanding universes holographically. The entanglement entropy of expanding universes increases according to the volume law in the early time and the area law in the late time. We also study the time-dependent quantum entanglement across the cosmological horizon.
Article
Physics, Multidisciplinary
Andronikos Paliathanasis
Summary: We address the group classification problem for gravitational field equations within the context of brane-world cosmology, considering the presence of a bulk scalar field. By applying the Lie symmetry condition, we find that only the exponential potential exhibits Lie symmetries, and we derive exact solutions for the system using Lie invariants.
Article
Astronomy & Astrophysics
Kareem Marzouk, Alessandro Maraio, David Seery
Summary: In this study, we update predictions for observables in the "delicate" D3/(D3) over bar inflationary model on the conifold. Our analysis shows that the model can accurately forecast the amplitude of three-point correlations. The model generally follows Maldacena's single-field prediction, but in some cases, the bispectrum is dominated by effects from rapid switching between angular minima, resulting in larger amplitudes but with unacceptable spectral behavior.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Abolhassan Mohammadi, Tayeb Golanbari, Jamil Enayati
Summary: The study shows that the constraint of trans-Planckian censorship conjecture imposes stricter limitations on the brane inflation model, depending on the brane tension and restricting the value of brane tension. Through the case of slowly varying Hubble parameter, interesting results are obtained for the epsilon and r, indicating that the value of the tensor-to-scalar perturbation does not need to be extremely small.
Article
Physics, Particles & Fields
F. Gomez, S. Lepe, P. Salgado
Summary: Based on the Einstein-Chern-Simons theory for gravity, solutions describing accelerated expansion, transient phantom evolution, and bouncing behavior were found for a four-dimensional brane embedded in a five-dimensional spacetime. The introduction of a kinetic term in the action showed de Sitter behavior and a possible geometric origin of dark energy was conjectured. These findings suggest a complex and dynamic nature of the universe.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Physics, Particles & Fields
Robert Brandenberger, Lavinia Heisenberg, Jakob Robnik
Summary: This study proposes a solution to the black hole singularity and enables an anisotropic cosmology to emerge inside the hole, addressing the information loss paradox. By adding an S-brane to the effective action describing space-time geometry, this model explores how metric fluctuations evolve from the black hole to the cosmological phase.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Physics, Multidisciplinary
J. Sadeghi, B. Pourhassan, S. Noori Gashti, S. Upadhyay
Summary: In this paper, a modified f(R) gravitational model is introduced to examine new conditions for inflation models in the expanding universe. By introducing modified cosmological parameters and applying them to the modified f(R) gravitational model, the range of each parameter is determined with respect to observable data such as Planck 2018.
Article
Physics, Multidisciplinary
Mojtaba Haghshenas, Tahereh Azizi
Summary: This paper investigates the effects of different braneworld gravity scenarios on the propagation of gravitational waves. It reveals that different scenarios lead to varying rates of amplitude and frequency reduction for brane gravitational waves. The RSII braneworld scenario shows more stable waves on the brane compared to the standard model. In the case of DGP gravity, the normal branch exhibits a rapid decay in amplitude and frequency for brane gravitational waves.
Article
Astronomy & Astrophysics
Cesar Hernandez-Aguayo, Christian Arnold, Baojiu Li, Carlton M. Baugh
Summary: In this study, 'full-physics' hydrodynamical simulations of galaxy formation in the nDGP braneworld model were conducted to investigate the impact of baryonic physics on galactic scales and make predictions on the stellar content of dark matter haloes and galaxy evolution. Significant differences between general relativity and nDGP models were found in the power spectra and correlation functions of gas, stars, and dark matter, with baryonic effects influencing the overall matter distribution clustering. The study also revealed that the effects of modified gravity and galactic feedback on matter clustering can be distinctly separated, allowing for accurate prediction of the matter power spectrum with baryonic effects included.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Cao H. Nam
Summary: Based on the swampland program, this study suggests that if this program is true, the brane-world scenario with branon dark matter would be ruled out. The constraints of quantum gravity imply that the branons must be absorbed by the KK gauge bosons, which leads to a geometric unification of gravity and dark matter. The KK gauge boson dark matter provides a promising observation window to search for weakly interacting dark matter in the cosmic microwave background and primordial gravitational waves.
Article
Astronomy & Astrophysics
Suddhasattwa Brahma, Robert Brandenberger, Ziwei Wang
Summary: The entanglement entropy of scalar perturbations due to gravitational non-linearities in a canonical, single-field ekpyrosis model was calculated in this study. By ensuring that the entanglement entropy remains subdominant to the thermal entropy generated during reheating, an upper bound on the energy scale of the bounce was obtained.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Review
Physics, Multidisciplinary
Theodore Erler
Summary: These notes are derived from review lectures on analytic solutions in open string field theory, which were given at the School for String Field Theory and String Phenomenology at the Harish-Chandra Research Institute in February 2018.
PHYSICS REPORTS-REVIEW SECTION OF PHYSICS LETTERS
(2022)
Article
Astronomy & Astrophysics
Elham Nouri, Hossein Motavalli, Amin Rezaei Akbarieh
Summary: This paper presents a generalized tachyonic dark energy scenario in a homogeneous and isotropic FLRW flat universe, where a noncanonical scalar field is nonminimally coupled to gravity. The tachyon field accelerates the evolution of the universe in the early times and plays a key role in dark energy in the late times. The study shows a cosmological degeneracy in the model, indicating the potential of the generalized tachyon field as a dark energy candidate.
INTERNATIONAL JOURNAL OF MODERN PHYSICS D
(2022)
Article
Astronomy & Astrophysics
Hossein Motavalli, Elham Nouri
Summary: This paper studies a cosmological model governed by a generalized scalar field nonminimally coupled to scalar torsion in the framework of teleparallel gravity. By applying the Noether symmetry approach, the explicit forms of the coupling function and the scalar field potential in the Friedmann-Lemaitre-Robertson-Walker (FLRW) flat spacetime are explored. The existence of such symmetry simplifies the equations of motion and provides an exponential form cosmological solution for both the scale factor and scalar field. It is shown that the tachyon field behaves as the origin of inflation and contributes significantly to the accelerating expansion of the universe in the early times. In the late times, the gravitational sources consist of a pressureless matter field together with the tachyon field, which plays the essential role of dark energy and is the origin of deceleration-acceleration phase transition. The paper also discusses the cosmological degeneracy of the model, indicating that different coupling parameters and tachyonic potentials can contribute to the same cosmological behaviors.
INTERNATIONAL JOURNAL OF MODERN PHYSICS D
(2022)
Article
Astronomy & Astrophysics
M. Malekjani, Jianbo Lu, N. Nazari-Pooya, Lixin Xu, D. Mohammad-Zadeh Jassur, M. Honari-Jafarpour
ASTROPHYSICS AND SPACE SCIENCE
(2015)
Article
Physics, Multidisciplinary
Yang Lei, Yang Wei-Qiang, Xu Li-Xin
CHINESE PHYSICS LETTERS
(2015)
Article
Physics, Multidisciplinary
Wei Li, Lixin Xu
JOURNAL OF EXPERIMENTAL AND THEORETICAL PHYSICS
(2015)
Article
Astronomy & Astrophysics
Lixin Xu
Article
Astronomy & Astrophysics
Lixin Xu
Article
Physics, Particles & Fields
Jianbo Lu, Danhua Geng, Lixin Xu, Yabo Wu, Molin Liu
JOURNAL OF HIGH ENERGY PHYSICS
(2015)
Article
Astronomy & Astrophysics
Weiqiang Yang, Lixin Xu
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2014)
Article
Astronomy & Astrophysics
Lixin Xu
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2014)
Article
Astronomy & Astrophysics
Lixin Xu
MODERN PHYSICS LETTERS A
(2014)
Article
Astronomy & Astrophysics
Jianbo Lu, Lixin Xu, Hongyan Tan, Shanshan Gao
Article
Astronomy & Astrophysics
Baorong Chang, Lixin Xu
Article
Astronomy & Astrophysics
Baorong Chang, Jianbo Lu, Lixin Xu
Article
Astronomy & Astrophysics
Yuhao Mu, En-Kun Li, Lixin Xu
Summary: In this paper, the reconstructed growth index is updated using a combination of Pantheon+ SNe Ia samples, observed Hubble data points, and redshift space distortion measurements. The results suggest a mild time varying growth index at low redshifts within the available data points. No significant deviation from the ΛCDM cosmology in GR was found within the 3 sigma regions, while the growth indices for f(R) and Dvali-Gabadadze-Porrati gravity are at the boundaries of the 3 sigma regions.
CLASSICAL AND QUANTUM GRAVITY
(2023)
Article
Astronomy & Astrophysics
Gang Liu, Zhihuan Zhou, Yuhao Mu, Lixin Xu
Summary: In this paper, the interaction between early dark energy and scalar field dark matter is investigated. A coupled model is proposed to address the tension in Hubble constant and S8 parameter. It is found that while the model alleviates the tension in Hubble constant, it exacerbates the tension in S8 parameter. The introduction of interaction between early dark energy and dark matter is suggested to mitigate the negative impact.
Article
Astronomy & Astrophysics
Hsien-Hao Mei, Wei-Tou Ni, Wei-Ping Pan, Lixin Xu, Sperello di Serego Alighieri
ASTROPHYSICAL JOURNAL
(2015)
