Article
Physics, Particles & Fields
Alvaro Restuccia, Francisco Tello-Ortiz
Summary: This study obtained and analyzed a spherically symmetric solution of the field equations of the Horava-Lifshitz gravity-gauge vector interaction theory, describing a charged throat. The solution exists when a restriction on the relation between mass and charge is met, reducing to the Reissner-Nordstrom one as the coupling constants approach relativistic values. By introducing the correct charts, the solution can be described across the entire manifold, including the throat connecting different spacetimes.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Astronomy & Astrophysics
Jan Ambjorn, Yuki Hiraga, Yoshiyasu Ito, Yuki Sato
Summary: By quantizing the two-dimensional projectable Horava-Lifshitz gravity with bi-local and spacelike wormhole interaction, we find that the resulting quantum Hamiltonian coincides with that obtained through summing over all genus in the string field theory, implying that the wormhole interaction can be interpreted as a splitting or joining interaction of one-dimensional strings.
Article
Astronomy & Astrophysics
Celia Escamilla-Rivera, Hernando Quevedo
Summary: Proposing an alternative cosmography using Horava-Lifshitz gravity as a model for quantum gravity, the study suggests that the Universe appears flat classically according to the ΛCDM model, but is actually curved from a quantum perspective. The findings indicate a non-flat scenario and a specific value for the Horava parameter that could be interpreted as a measure of a quantum effect.
CLASSICAL AND QUANTUM GRAVITY
(2021)
Article
Astronomy & Astrophysics
Hiroki Matsui, Shinji Mukohyama, Atsushi Naruko
Summary: The study shows that in many gravitational theories, the DeWitt wave function does not have the desired form when tensor perturbations are taken into account, but Hofava-Lifshitz gravity provides a satisfactory solution, especially an exact analytic expression for the DeWitt wave function of the universe with scale-invariant perturbations can be found in the limit of z = 3 anisotropic scaling.
Article
Astronomy & Astrophysics
Kyungmin Kim, John J. Oh, Chan Park, Edwin J. Son
Summary: The study revealed that neutron stars (NSs) with larger radii and heavier masses in Ho.rava-Lifshitz (HL) gravity remain stable without collapsing into black holes, showing a deviation from general relativity (GR) can change the typical features of NS structure.
Article
Astronomy & Astrophysics
Paul Martens, Hiroki Matsui, Shinji Mukohyama
Summary: In this paper, we introduce a well-tempered DeWitt wave function that vanishes at the classical big-bang singularity in Horava-Lifshitz (HL) cosmology. Through analytical and numerical methods, we demonstrate that in HL gravity, the DeWitt wave function for tensor perturbation is well-defined at the singularity and behaves well up to the finite size of the Universe.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
G. S. Vicente
Summary: This study considers classical and quantum Friedmann-Lemaitre-Robertson-Walker universes filled with noninteracting radiation and dust fluids within the framework of Horava-Lifshitz gravity theory. Analytical solutions for nonsingular quantum bounce and cyclic universes for open and closed spatial sections in terms of the parameters of Horava-Lifshitz theory were found. The Horava-Lifshitz theory was applied in its projectable version without the detailed balance condition, and canonical quantization was performed in the Wheeler-DeWitt approach of quantum cosmology for a minisuperspace model.
Article
Astronomy & Astrophysics
Ewa Czuchry
Summary: The standard ΛCDM model has unresolved issues like the initial singularity, which require modifications to general relativity. However, the Horava-Lifshitz theory offers an alternative with a bounce of the universe instead of an initial singularity. This review discusses previous works on the stability of this bounce in different formulations of the HL theory.
Article
Astronomy & Astrophysics
Nicola Bartolo, Alexander Ganz, Sabino Matarrese
Summary: In this study, we investigate the impact of (generalized) cuscuton models on standard single scalar field inflation and find that the presence of a non-dynamical scalar field does not spoil inflation but instead leads to modifications that are slow-roll suppressed, resulting in almost scale invariant power spectra. However, the additional free parameters in this model can be tuned independently, allowing for a larger range of observable quantities.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Hugo Garcia-Compean, Daniel Mata-Pacheco
Summary: This study investigates the vacuum transition probabilities for a Friedmann-Lemaitre-Robertson-Walker universe with positive curvature in Horava-Lifshitz gravity, considering the presence of a scalar field potential. The Hamiltonian approach to the Wheeler-DeWitt equation is used to compute the transition probabilities. The study provides analytic expressions for the transition probabilities in two scenarios and discusses the infrared and ultraviolet limits in comparison to general relativity. Phenomenological implications, including a potential resolution of the initial singularity, are briefly discussed.
Article
Multidisciplinary Sciences
Abdul Jawad, Abdul Malik Sultan, Shamaila Rani
Summary: In this study, the matter-antimatter imbalance in the universe is investigated through baryogenesis, which is a physical process occurring after the big bang and resulting in an excess of matter over antimatter. The reproduction of the baryon to entropy ratio in the presence of modified Ho.rava-Lifshitz gravity is examined, considering different baryogenesis interactions proportional to (R) over tilde. Two models are analyzed with different values of F((R) over tilde). The results show that the matter-antimatter asymmetry is not eliminated by the modified gravity theory, indicating a consistent gravitational baryogenesis with recent observational data.
Article
Physics, Mathematical
Abdul Jawad, Shamaila Rani, Sameen Ashraf, Nadeem Azhar
Summary: We discuss the cosmological implications of the interacting Barrow holographic dark energy model in the context of flat deformed Horava-Lifshitz gravity by assuming the interaction between dark energy and pressureless dark matter. We investigate the evolutionary history of cosmological parameters and find results that favor observational data of Planck 2018. Moreover, we examine the generalized second law of thermodynamics of this cosmological system with barrow entropy as horizon entropy and observe that this law holds for both horizons.
INTERNATIONAL JOURNAL OF GEOMETRIC METHODS IN MODERN PHYSICS
(2022)
Article
Physics, Particles & Fields
Hongbo Cheng
Summary: This study investigates the Casimir force for parallel plates at finite temperature in the Horava-Lifshitz (HL) theory. It is found that the HL exponent cannot be chosen as an integer, otherwise the Casimir energy will be a constant, resulting in the disappearance of Casimir force between two parallel plates. Higher temperature weakens the attractive Casimir force, which is consistent with previous theoretical and experimental results. By appropriately selecting the HL factor, a thermally revised Casimir force similar to the standard results for parallel plates can be obtained.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Astronomy & Astrophysics
Alvaro Restuccia, Francisco Tello-Ortiz
Summary: An anisotropic model describing gravity-vector gauge coupling is proposed, based on the 4+1 dimensional non-projectable Ho.rava-Lifshitz gravity theory with a geometrical restriction. Renormalizability arguments require including interactions up to terms with z = 4 spatial derivatives on the geometrical tensor fields. The reduction to 3+1 dimensions results in a model invariant under FDiff and U(1) symmetry groups, propagating the same spectrum as the Einstein-Maxwell theory at the kinetic conformal point.
CLASSICAL AND QUANTUM GRAVITY
(2023)
Article
Astronomy & Astrophysics
Mohammad Bagher Jahani Poshteh, Robert B. Mann
Summary: The thermodynamics of z = 4 Ho.rava-Lifshitz black holes in 3 + 1 dimensions is studied in extended phase space. By using the scaling argument, the Smarr relation and the first law for the black hole solutions of z = 4 Ho.rava-Lifshitz gravity are found. It is discovered that the reverse isoperimetric inequality can be violated for certain types of horizons, leading to positive specific heat at constant pressure and volume. Two critical points are identified for z = 4 Hovara-Lifshitz black holes with hyperbolic horizons, exhibiting both Van der Waals and reverse Van der Waals behaviors.
Article
Astronomy & Astrophysics
Nosiphiwo Zwane, Niayesh Afshordi, Rafael D. Sorkin
CLASSICAL AND QUANTUM GRAVITY
(2018)
Article
Astronomy & Astrophysics
Chiamaka Okoli, James E. Taylor, Niayesh Afshordi
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2018)
Article
Astronomy & Astrophysics
Morgan H. Lynch, Niayesh Afshordi
CLASSICAL AND QUANTUM GRAVITY
(2018)
Review
Astronomy & Astrophysics
Jahed Abedi, Niayesh Afshordi, Naritaka Oshita, Qingwen Wang
Article
Astronomy & Astrophysics
Matthew P. G. Robbins, Niayesh Afshordi, Alan O. Jamison, Robert B. Mann
Summary: This article presents an interesting proposal for detecting gravitational waves using Bose-Einstein condensates. By modulating the speed of sound in the condensate, the sensitivity to gravitational waves can be enhanced. The study finds that such a detector has the potential to detect gravitational waves across a wide range of frequencies.
CLASSICAL AND QUANTUM GRAVITY
(2022)
Article
Astronomy & Astrophysics
Alice Y. Chen, Niayesh Afshordi
Summary: Halo models of large scale structure are important for understanding the clustering of matter in the Universe. This paper addresses the issue of defining halo profiles beyond their virial radii and provides a systematic definition that can be matched to simulation results. The compensating halo profiles are crucial for the calculation of cosmological correlation functions in an amended halo model.
Article
Astronomy & Astrophysics
Niayesh Afshordi, Joao Magueijo
Summary: In this study, the researchers use the quantum unimodular theory of gravity to investigate the relationship between the cosmological constant and the energy scale for the emergence of cosmological classicality. The findings suggest that a perennially quantum Universe would occur if the cosmological constant is zero. The study also establishes a lower bound on the uncertainty of the unimodular clock or the cosmic time for the emergence of classicality based on the smallness of the cosmological constant. Classicality arises at around 7 x 1011 GeV for the observed value of the cosmological constant, highlighting the importance of understanding the classicality and quantum nature of the Universe.
Article
Astronomy & Astrophysics
Luis Felipe Longo Micchi, Niayesh Afshordi, Cecilia Chirenti
Summary: The first direct observations of gravitational waves by the LIGO collaboration have led to different tests of general relativity. One of these tests involves searching for extra pulses following the gravitational waveform. A new study provides estimates for the detectability of the first echo, suggesting that it may be detected by LIGO in the next few years.
Article
Astronomy & Astrophysics
Naritaka Oshita, Daichi Tsuna, Niayesh Afshordi
Article
Astronomy & Astrophysics
Alice Y. Chen, Niayesh Afshordi
Article
Astronomy & Astrophysics
Qingwen Wang, Niayesh Afshordi
Article
Astronomy & Astrophysics
Niayesh Afshordi, Matthew C. Johnson
Article
Astronomy & Astrophysics
Jahed Abedi, Hannah Dykaar, Niayesh Afshordi
Article
Astronomy & Astrophysics
Yasaman K. Yazdi, Niayesh Afshordi
ASTROPHYSICAL JOURNAL
(2017)
Article
Astronomy & Astrophysics
Niayesh Afshordi, Elizabeth Gould, Kostas Skenderis