Article
Multidisciplinary Sciences
Samuel Beaulieu, Shuo Dong, Nicolas Tancogne-Dejean, Maciej Dendzik, Tommaso Pincelli, Julian Maklar, R. Patrick Xian, Michael A. Sentef, Martin Wolf, Angel Rubio, Laurenz Rettig, Ralph Ernstorfer
Summary: Fermi surface plays a crucial role in understanding metals and correlated many-body systems. While Lifshitz transitions have been demonstrated in a broad range of materials by equilibrium tuning, an experimental demonstration of a nonequilibrium dynamical route for ultrafast modification of Fermi surface topology is lacking. This study introduces a scheme for driving an ultrafast Lifshitz transition in a correlated type-II Weyl semimetal, shedding light on a previously unexplored ultrafast scheme for controlling Fermi surface topology.
Article
Astronomy & Astrophysics
Jan Ambjorn, Zbigniew Drogosz, Jakub Gizbert-Studnicki, Andrzej Gorlich, Jerzy Jurkiewicz, Daniel Nemeth
Summary: This article discusses the complex geometries extracted from the path integral of a quantum theory of gravity, showing that using suitable coordinate systems and scalar fields that solve Laplace's equation can help understand cosmic voids and filaments structures. It also demonstrates the dramatic changes in geometry that can occur when scalar fields are dynamically coupled to the geometry.
CLASSICAL AND QUANTUM GRAVITY
(2021)
Article
Astronomy & Astrophysics
Alexandru Dima, Miguel Bezares, Enrico Barausse
Summary: The study tests the validity of chameleon screening in strong-field and highly relativistic/dynamical conditions, finding that screened chameleon stars are stable to small oscillations but show deviations in frequency spectrum from general relativistic predictions. Additionally, the scalar fluxes produced during collapse to a black hole may be detectable with future gravitational-wave interferometers.
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
Anton Galajinsky
Summary: This study investigates the dynamical realizations of the Lifshitz group within the framework of group theory. A generalized version of 1d conformal mechanics is constructed, involving an arbitrary dynamical exponent z. A similar generalization of the Ermakov-Milne-Pinney equation is proposed. Invariant derivative and field combinations are introduced, enabling the construction of numerous dynamical systems with Lifshitz symmetry. A metric and energy-momentum tensor are constructed in (d + 2)-dimensional spacetime, which leads to a generalized Ermakov-Milne-Pinney equation when the Einstein equations are imposed. The method of nonlinear realizations is used to build Lorentzian metrics with the Lifshitz isometry group, including a (2d + 2)-dimensional metric with additional invariance under Galilei boosts.
Article
Multidisciplinary Sciences
Rodrigo R. Cuzinatto, Rajendra P. Gupta, Pedro J. Pompeia
Summary: In this study, a scalar-tensor theory of gravity is investigated, where the gravitational coupling and the speed of light are considered as space-time functions and define the scalar field. The cosmological coupling is analyzed to show the existence of an attractor point in the phase space. The condition for the coupling ratio between the gravitational coupling and the speed of light is derived for the cosmic evolution after reaching a stable fixed point. The impact of covarying gravitational coupling and speed of light on cosmic evolution is investigated by constructing a generalized continuity equation and solving modified Friedmann equations.
Article
Astronomy & Astrophysics
Danilo C. Moreira
Summary: In this work, we investigate the existence of analytic solutions of static scalar fields on Lifshitz spacetimes. By breaking general covariance and using first-order formalism, we obtain solutions with finite energy that are related to the time-translational invariance of the background geometry and the energy-momentum tensor of the model. We show that such solutions exist and are stable in systems where the Lifshitz background geometry is fixed and the self-interaction potential of the scalar field explicitly depends on the radial coordinate present in the metric.
Article
Physics, Particles & Fields
Shao-Jun Zhang
Summary: A study was conducted on massive scalar field perturbation on Kerr black holes in dynamical Chern-Simons gravity through a (2+1)-dimensional simulation. It was found that tachyonic instability always occurs when the coupling constant exceeds a critical value, for any nonzero black hole spin and any scalar field mass. The presence of a mass term suppresses or even quenches the instability, with the quantitative dependence of the onset of tachyonic instability on the coupling constant, scalar field mass, and black hole spin given numerically.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Astronomy & Astrophysics
Anna Ijjas, Frans Pretorius, Paul J. Steinhardt, David Garfinkle
Summary: The study presents non-perturbative numerical relativity simulations of two scalar fields coupled through a non-linear model-type kinetic interaction, showing that the non-linear evolution tends towards a homogeneous, isotropic, and flat FRW geometry for various initial conditions. However, the kinetic coupling causes the evolution to deviate towards a novel Kasner-like stationary point, occurring on time scales that are too long to be observationally relevant.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Physics, Particles & Fields
Dario Zappala
Summary: We investigate Lifshitz-type scalar field theories that exhibit anisotropic scaling laws and explicit breaking of Lorentz symmetry near the ultraviolet fixed point. It is found that, when all momentum dependent vertex operators are discarded, actions with an anisotropy parameter z = 3 in 3+1 dimensions generate Lorentz symmetry violating quantum corrections that are suppressed by inverse powers of the momentum, thereby restoring the symmetry in the infrared region. In the ultraviolet region, the singular behavior of the corrections is strongly smoothened, with only logarithmic divergences appearing and causing negligible changes in the couplings. For a special case where all couplings are equal, the theory exhibits a Liouville-like potential and the quantum corrections can be exactly summed, resulting in an asymptotically free theory. However, despite the weakening of the divergences, there is still a need for fine tuning of the mass parameter at a very high energy scale to obtain a physically acceptable mass in the infrared region.
EUROPEAN PHYSICAL JOURNAL C
(2022)
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
J. Ambjorn, Z. Drogosz, A. Gorlich, J. Jurkiewicz
Summary: The study reveals that the geometry of a quantum universe with a four-torus topology consists of a small semiclassical toroidal bulk part surrounded by many outgrowths with almost spherical topologies, yet still quite fractal.
Article
Astronomy & Astrophysics
Moises Bravo-Gaete, Maria Montserrat Juarez-Aubry, Gerardo Velazquez Rodriguez
Summary: In this work, we study the existence of asymptotically Lifshitz black holes in four dimensions with a negative cosmological constant. We consider two scenarios, including dilatonic fields and a nonminimally coupled scalar field. We find solutions for specific values of the dynamical exponent, as well as additional solutions in the limiting case. We also study the thermodynamics of these new solutions and find that they satisfy the first law of thermodynamics and the Smarr relation.
Article
Astronomy & Astrophysics
M. Blagojevic, B. Cvetkovic
Summary: The Hamiltonian approach to black hole entropy, within the framework of Poincare gauge theory, is expanded to include scalar matter. This improved approach is applied to analyze the asymptotic charges and entropy of a black hole with scalar hair in both General Relativity and teleparallel gravity, confirming the validity of the first law in both cases.
Article
Astronomy & Astrophysics
D. C. Moreira, F. A. Brito, J. C. Mota-Silva
Summary: We study classical scalar fields in asymptotically Lifshitz spacetimes and find spatially localized solutions in the probe field limit. By introducing a mechanism that breaks diffeo-morphism invariance, we obtain a Lifshitz black hole solution by including a backreaction with a cosmological constant and a Maxwell term coupled to a dielectric function.
