Article
Physics, Nuclear
Dharm Veer Singh, Sudhaker Upadhyay, Md Sabir Ali
Summary: In this study, a singular solution is derived for the rotating counterpart of Lee-Wick gravity with a point source in a higher-derivative theory. The thermodynamics of this thermal system, including mass parameters, angular velocity, and Hawking temperature, is critically analyzed. The first law of thermodynamics is found to be valid, and the expression of entropy is obtained. The stability and phase transition of the theory are further discussed by evaluating heat capacity and free energy, revealing that the stability of the black hole is dependent on the horizon radius.
INTERNATIONAL JOURNAL OF MODERN PHYSICS A
(2022)
Article
Physics, Multidisciplinary
Hou-Yu Lin, Xue-Mei Deng
Summary: This study investigates the precessing and periodic motions of neutral massive particles around Lee-Wick black holes. It derives the secular periastron precession and obtains a preliminary bound on the UV scale of the spacetime using the orbit of S2 star around Sgr A* as a reference. The results show that precessing in the weak gravitational field is similar to Schwarzschild black holes and that the variation of the UV scale can change the taxonomy for the particles' quasi-periodic and periodic motions, allowing for a transition between the two.
EUROPEAN PHYSICAL JOURNAL PLUS
(2022)
Article
Oceanography
Yue Wu, Eric Kunze, Amit Tandon, Amala Mahadevan
Summary: Microstructure measurements in the Antarctic Circumpolar Currents find weaker dissipation rates of lee waves than predicted, suggesting reabsorption of wave radiation into bottom-intensified flows. Numerical simulations of a bottom-intensified, laterally confined jet show that only 14% of lee wave generation is dissipated, with the majority reabsorbed by the flow. Water column reabsorption needs to be considered as a possible mechanism for reducing the dissipative sink of lee waves in balanced circulation.
JOURNAL OF PHYSICAL OCEANOGRAPHY
(2023)
Article
Thermodynamics
Xuewei Jiang, Hai Tang, Ying Liu, Lixian Lian
Summary: By fabricating multi-layer wick heat pipes, the heat transfer performance in the anti-gravity direction was effectively improved, with a higher critical heat load compared to traditional homogeneous wick heat pipes. This will expand the applications of multi-layer wick heat pipes in terrestrial environments.
APPLIED THERMAL ENGINEERING
(2022)
Article
Meteorology & Atmospheric Sciences
P. -D. Pautet, M. J. Taylor, D. C. Fritts, D. Janches, N. Kaifler, A. Dornbrack, J. L. Hormaechea
Summary: This article discusses the characteristics and impacts of gravity waves (GWs) generated by orographic forcing, also known as mountain waves (MWs), in the upper atmosphere, as well as the extent to which these impacts are influenced by the background environment. Through observational data from the Southern Hemisphere winter of 2018, it reveals the frequency of occurrence of MWs at mesospheric altitudes and their correlation with the atmospheric background.
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES
(2021)
Article
Mechanics
Guillaume Michel, Felicien Bonnefoy, Guillaume Ducrozet, Eric Falcon
Summary: This study investigates the statistics of rogue waves occurring in the inverse cascade of surface gravity wave turbulence. It reveals that in statistically homogeneous, stationary and isotropic wave fields, low-frequency waves are generated by nonlinear interactions instead of direct forcing. The analysis of thousands of rogue waves shows that certain properties crucially depend on four-wave resonant interactions, with larger crests being more likely than predicted by second-order models.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Astronomy & Astrophysics
Katsuki Aoki, Masato Minamitsuji
Summary: This paper discusses the issues of singular effective metric and gradient or ghost instabilities in a self-interacting massive vector field. The research finds that the singularity formation is not necessarily a fundamental problem, but a breakdown of the effective field theory (EFT) description. It is also discovered that the EFT description breaks before the onset of the ghost instability.
Article
Astronomy & Astrophysics
Nils A. Nilsson
Summary: In this study, we investigate the effects of explicit spacetime-symmetry breaking on primordial tensor fluctuations using an effective-field theory for Lorentz/CPT violation. Our findings show that despite the symmetry breaking, the graviton remains massless, but the propagation speed of tensor modes is modified. We also derive a constraint on the coefficient determining the symmetry breaking based on recent measurements of the speed of gravity. Additionally, due to the symmetry breaking, the de-Sitter phase is altered, resulting in a slow oscillation of the power spectrum during the inflationary epoch. Furthermore, we observe that while the primordial tensor power spectrum maintains scale invariance, its amplitude is modified. Moreover, we find that the modes which become subhorizon during radiation domination experience a phase shift proportional to the coefficient for Lorentz violation.
Article
Physics, Multidisciplinary
Taishi Ikeda, Vitor Cardoso, Miguel Zilhao
Summary: The behavior of fundamental fields in strong gravity or nontrivial environments plays a vital role in understanding nature. In this study, the dynamics of scalar fields in dynamic backgrounds were investigated, revealing implications for constraining the parameter space of scalar-tensor theories. The study sheds light on the significance of studying fundamental fields in dynamic environments.
PHYSICAL REVIEW LETTERS
(2021)
Article
Astronomy & Astrophysics
Enrico Barausse, Miguel Bezares, Marco Crisostomi, Guillermo Lara
Summary: We argue that the same techniques used to evolve the Cauchy problem for first-order derivative self-interacting scalar fields can also be applied to self-interacting vector fields, avoiding the issues and pathologies recently found in the literature.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Thermodynamics
Jie Zhao, Yang Ji, Da-Zhong Yuan, Yu-Xiang Guo, Shui-Wen Zhou
Summary: This study proposes a composite wick to optimize the anti-gravity heat transfer performance of a concentric annular high temperature heat pipe. The experimental results show that the dense pore-sparse pore-dense pore screen combination can achieve stable anti-gravity operation, and the composite wick has an impact on the anti-gravity heat transfer performance of the heat pipe.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2022)
Article
Astronomy & Astrophysics
Anamaria Hell
Summary: This study compares the massive Kalb-Ramond and Proca fields with a quartic self-interaction, and shows that they have the same strong coupling scale. However, the different modes in these theories behave differently beyond the strong coupling scale, indicating a potential contradiction with claims in the literature about their duality.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Oceanography
Hui Sun, Qingxuan Yang, Kaiwen Zheng, Wei Zhao, Xiaodong Huang, Jiwei Tian
Summary: This study improves the linear lee wave theory by considering shear background flow and viscous and diffusive effects. The influences of different types of shear flow on various aspects of lee waves are explored. It is found that a bottom-up decreasing background flow can enhance energy dissipation and irreversible mixing, but in a depth integrated sense, the dissipation and mixing caused by a decreasing background flow may be weaker than that caused by an increasing background flow.
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
(2022)
Article
Astronomy & Astrophysics
Nicolo Burzilla, Breno L. Giacchini, Tiberio de Paula Netto, Leonardo Modesto
Summary: In this paper, we analyze the static spherically symmetric solutions of a sixth-derivative Lee-Wick gravity model and find interesting structures in the full parameter space, including horizon structures, mass gaps, and multiple regimes for black hole sizes. The thermodynamics of these solutions exhibit multiple mass scales for the remnants of the evaporation process and the possibility of cold black holes and quasi-stable intermediate configurations.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Thermodynamics
Wissam H. Alawee, F. A. Essa, Suha A. Mohammed, Hayder A. Dhahad, A. S. Abdullah, Z. M. Omara, Y. Gamiel
Summary: This study introduces a new mechanism of using wick materials inside the solar still to enhance productivity, achieved by creating cracks and utilizing cords to keep the wick surface wet. Experimental results show that the thermal performance of cords wick solar still outperforms conventional solar still, with jute wick providing better performance. The optimal productivity was obtained with 25 cords, showing a significant increase in efficiency compared to the traditional solar still.
CASE STUDIES IN THERMAL ENGINEERING
(2021)
Article
Astronomy & Astrophysics
Nelson R. F. Braga, Octavio C. Junqueira
Summary: This study investigates the influence of rotation on the transition temperature of strongly interacting matter produced in non-central heavy ion collisions. By using a holographic description of an AdS black hole, the authors extend the analysis to the more realistic case where the matter spreads over a region around the rotational axis. The results show the coexistence of confined and deconfined phases and are consistent with the concept of local temperature in rotating frames developed by Tolman and Ehrenfest.
Article
Astronomy & Astrophysics
Bing Sun, Jiachen An, Zhoujian Cao
Summary: This paper investigates the effect of gravitational constant variation on the propagation of gravitational waves. By employing two analytical methods, the study finds that variations in the gravitational constant result in amplitude and phase corrections for gravitational waves, and the time variation of the gravitational constant can be constrained through the propagation of gravitational waves.
Article
Astronomy & Astrophysics
Abdellah Touati, Zaim Slimane
Summary: This letter presents the first study of Hawking radiation as a tunneling process within the framework of non-commutative gauge theory of gravity. The non-commutative Schwarzschild black hole is reconstructed using the Seiberg-Witten map and the star product. The emission spectrum of outgoing massless particles is computed using the quantum tunneling mechanism. The results reveal pure thermal radiation in the low-frequency scenario, but a deviation from pure thermal radiation in the high-frequency scenario due to energy conservation. It is also found that noncommutativity enhances the correlations between successively emitted particles.
Article
Astronomy & Astrophysics
Shahar Hod
Summary: The travel times of light signals between two antipodal points on a compact star's surface are calculated for two different trajectories. It is shown that, for highly dense stars, the longer trajectory along the surface may have a shorter travel time as measured by asymptotic observers. A critical value of the dimensionless density-area parameter is determined for constant density stars to distinguish cases where crossing through the star's center or following a semi-circular trajectory on the surface has a shorter travel time as measured by asymptotic observers.