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Showing papers on "Gravitation published in 2022"


Journal ArticleDOI
TL;DR: In this paper , the authors measured a linear frequency gradient consistent with the gravitational redshift within a single millimeter scale sample of ultracold strontium and improved the fractional frequency measurement uncertainty by more than a factor of 10, reaching 7.6$\times 10^{-21}$.
Abstract: Einstein's theory of general relativity states that clocks at different gravitational potentials tick at different rates - an effect known as the gravitational redshift. As fundamental probes of space and time, atomic clocks have long served to test this prediction at distance scales from 30 centimeters to thousands of kilometers. Ultimately, clocks will study the union of general relativity and quantum mechanics once they become sensitive to the finite wavefunction of quantum objects oscillating in curved spacetime. Towards this regime, we measure a linear frequency gradient consistent with the gravitational redshift within a single millimeter scale sample of ultracold strontium. Our result is enabled by improving the fractional frequency measurement uncertainty by more than a factor of 10, now reaching 7.6$\times 10^{-21}$. This heralds a new regime of clock operation necessitating intra-sample corrections for gravitational perturbations.

82 citations


Journal ArticleDOI
K. G. Arun, Enis Belgacem, Robert Benkel, Laura Bernard, Emanuele Berti, Gianfranco Bertone, Marc Besancon, Diego Blas, Christian G. Böhmer, Richard Brito, Gianluca Calcagni, Alejandro Cárdenas-Avendaño, Katy Clough, Marco Crisostomi, V. De Luca, Daniela D. Doneva, Stephanie Escoffier, Jose María Ezquiaga, Pedro G. Ferreira, Pierre Fleury, Stefano Foffa, Gabriele Franciolini, Noemi Frusciante, Juan Garcia-Bellido, Carlos A. R. Herdeiro, Thomas Hertog, Tanja Hinderer, Philippe Jetzer, Lucas Lombriser, Elisa Maggio, Michele Maggiore, Michele Mancarella, Andrea Maselli, Sourabh Nampalliwar, David A. Nichols, Maria Okounkova, Paolo Pani, Vasileios Paschalidis, Alvise Raccanelli, Lisa Randall, Sébastien Renaux-Petel, Antonio Riotto, Milton Ruiz, A. Saffer, Mairi Sakellariadou, Ippocratis D. Saltas, B. Sathyaprakash, Lijing Shao, Carlos F. Sopuerta, Thomas P. Sotiriou, Nikolaos Stergioulas, Nicola Tamanini, Filippo Vernizzi, Helvi Witek, Kinwah Wu, Kent Yagi, Stoytcho S. Yazadjiev, Nicolás Yunes, Miguel Zilhão, Niayesh Afshordi, M. C. Angonin, Vishal Baibhav, Enrico Barausse, T. Barreiro, N. Bartolo, Nicolas Bellomo, Ido Ben-Dayan, Eric Bergshoeff, Sebastiano Bernuzzi, Daniele Bertacca, Swetha Bhagwat, Béatrice Bonga, Lior M. Burko, Geoffrey Compère, Giulia Cusin, Antonio C. da Silva, Saurya Das, Claudia de Rham, Kyriakos Destounis, Emanuela Dimastrogiovanni, F. Duque, Richard Easther, Hontas Farmer, Matteo Fasiello, S. Fisenko, Kwinten Fransen, Jörg Frauendiener, Jonathan R. Gair, László Á. Gergely, Davide Gerosa, Leonardo Gualtieri, Wen-Biao Han, Aurélien Hees, Thomas Helfer, J. Hennig, Alexander C. Jenkins, E. Kajfasz, Nemanja Kaloper, Vladimir Karas, Bradley J. Kavanagh, Sergei A. Klioner, Savvas M. Koushiappas, Macarena Lagos, C. Le Poncin-Lafitte, Francisco S. N. Lobo, Charalampos Markakis, Prado Martín-Moruno, Carlos Martins, Sabino Matarrese, Daniel R. Mayerson, José P. Mimoso, Johannes Noller, Nelson J. Nunes, Roberto Oliveri, Giorgio Orlando, George J. Pappas, Igor Pikovski, Luigi Pilo, Jiří Podolský, Geraint Pratten, Tomislav Prokopec, H. Qi, Saeed Rastgoo, Angelo Ricciardone, Rocco Rollo, Diego Rubiera-Garcia, Olga Sergijenko, Stuart Shapiro, D. M. Shoemaker, Alessandro D. A. M. Spallicci, O. S. Stashko, Leo C. Stein, Gianmassimo Tasinato, Andrew J. Tolley, Elias C. Vagenas, Stefan Vandoren, Daniele Vernieri, Rodrigo Vicente, Toby Wiseman, V. I. Zhdanov, Miguel Zumalac'arregui 
TL;DR: In this article , the Fundamental Physics Working Group of the LISA Consortium summarizes the current topics in fundamental physics where LISA observations of gravitational waves can be expected to provide key input.
Abstract: Abstract The Laser Interferometer Space Antenna (LISA) has the potential to reveal wonders about the fundamental theory of nature at play in the extreme gravity regime, where the gravitational interaction is both strong and dynamical. In this white paper, the Fundamental Physics Working Group of the LISA Consortium summarizes the current topics in fundamental physics where LISA observations of gravitational waves can be expected to provide key input. We provide the briefest of reviews to then delineate avenues for future research directions and to discuss connections between this working group, other working groups and the consortium work package teams. These connections must be developed for LISA to live up to its science potential in these areas.

71 citations


Journal ArticleDOI
TL;DR: In this paper , it was shown that the energy of an excitation localized to an island can be detected from outside the island, in contradiction with the principle that operators in an entanglement wedge should commute with operators from its complement.
Abstract: In ordinary gravitational theories, any local bulk operator in an entanglement wedge is accompanied by a long-range gravitational dressing that extends to the asymptotic part of the wedge. Islands are the only known examples of entanglement wedges that are disconnected from the asymptotic region of spacetime. In this paper, we show that the lack of an asymptotic region in islands creates a potential puzzle that involves the gravitational Gauss law, independently of whether or not there is a non-gravitational bath. In a theory with long-range gravity, the energy of an excitation localized to the island can be detected from outside the island, in contradiction with the principle that operators in an entanglement wedge should commute with operators from its complement. In several known examples, we show that this tension is resolved because islands appear in conjunction with a massive graviton. We also derive some additional consistency conditions that must be obeyed by islands in decoupled systems. Our arguments suggest that islands might not constitute consistent entanglement wedges in standard theories of massless gravity where the Gauss law applies.

70 citations


Journal ArticleDOI
TL;DR: In this paper , the effects of a Gauss-Bonnet term in four space-time dimensions by re-scaling the appropriate coupling parameter are discussed. And the authors discuss the mathematical complexities involved in implementing this idea, and review recent attempts at constructing well defined, self-consistent theories that enact it.
Abstract: We review the topic of 4D Einstein–Gauss–Bonnet (4DEGB) gravity, which has been the subject of considerable interest over the past two years. Our review begins with a general introduction to Lovelock’s theorem, and the subject of Gauss–Bonnet terms in the action for gravity. These areas are of fundamental importance for understanding modified theories of gravity, and inform our subsequent discussion of recent attempts to include the effects of a Gauss–Bonnet term in four space–time dimensions by re-scaling the appropriate coupling parameter. We discuss the mathematical complexities involved in implementing this idea, and review recent attempts at constructing well-defined, self-consistent theories that enact it. We then move on to consider the gravitational physics that results from these theories, in the context of black holes, cosmology, and weak-field gravity. We show that 4DEGB gravity exhibits a number of interesting phenomena in each of these areas.

65 citations


Journal ArticleDOI
14 Jan 2022-Science
TL;DR: Results show that gravity creates Aharonov-Bohm phase shifts analogous to those produced by electromagnetic interactions, as predicted by quantum mechanics.
Abstract: Description Gravitational interference The Aharonov-Bohm effect is a quantum mechanical effect in which a magnetic field affects the phase of an electron wave as it propagates along a wire. Atom interferometry exploits the wave characteristic of atoms to measure tiny differences in phase as they take different paths through the arms of an interferometer. Overstreet et al. split a cloud of cold rubidium atoms into two atomic wave packets about 25 centimeters apart and subjected one of the wave packets to gravitational interaction with a large mass (see the Perspective by Roura). The authors state that the observed phase shift is consistent with a gravitational Aharonov-Bohm effect. —ISO Atom interferometry was used to detect a gravitational Aharonov-Bohm effect. Gravity curves space and time. This can lead to proper time differences between freely falling, nonlocal trajectories. A spatial superposition of a massive particle is predicted to be sensitive to this effect. We measure the gravitational phase shift induced in a matter-wave interferometer by a kilogram-scale source mass close to one of the wave packets. Deflections of each interferometer arm due to the source mass are independently measured. The phase shift deviates from the deflection-induced phase contribution, as predicted by quantum mechanics. In addition, the observed scaling of the phase shift is consistent with Heisenberg’s error-disturbance relation. These results show that gravity creates Aharonov-Bohm phase shifts analogous to those produced by electromagnetic interactions.

48 citations


Journal ArticleDOI
24 Mar 2022
TL;DR: In this article , the double copy of three-point amplitudes has been studied in the context of gravity and general relativity, and it has been shown that it can extend elegantly to exact solutions.
Abstract: Scattering amplitudes have their origin in quantum field theory, but have wide-ranging applications extending to classical physics. We review a formalism to connect certain classical observables to scattering amplitudes. An advantage of this formalism is that it enables us to study implications of the double copy in classical gravity. We discuss examples of observables including the total change of a particle’s momentum, and the gravitational waveform, during a scattering encounter. The double copy also allows direct access to classical solutions in gravity. We review this classical double copy starting from its linearised level, where it originates in the double copy of three-point amplitudes. The classical double copy extends elegantly to exact solutions, making a connection between scattering amplitudes and the geometric formulation of general relativity.

42 citations



Journal ArticleDOI
K. G. Arun, Enis Belgacem, Robert Benkel, Laura Bernard, Emanuele Berti, Gianfranco Bertone, Marc Besancon, Diego Blas, Christian G. Böhmer, Richard Brito, Gianluca Calcagni, Alejandro Cárdenas-Avendaño, Katy Clough, Marco Crisostomi, V. De Luca, Daniela D. Doneva, Stephanie Escoffier, Jose María Ezquiaga, Pedro G. Ferreira, Pierre Fleury, Stefano Foffa, Gabriele Franciolini, Noemi Frusciante, Juan Garcia-Bellido, Carlos A. R. Herdeiro, Thomas Hertog, Tanja Hinderer, Philippe Jetzer, Lucas Lombriser, Elisa Maggio, Michele Maggiore, Michele Mancarella, Andrea Maselli, Sourabh Nampalliwar, David A. Nichols, Maria Okounkova, Paolo Pani, Vasileios Paschalidis, Alvise Raccanelli, Lisa Randall, Sébastien Renaux-Petel, Antonio Riotto, Milton Ruiz, A. Saffer, Mairi Sakellariadou, Ippocratis D. Saltas, Bangalore Suryanarayana Sathyaprakash, Lijing Shao, Carlos F. Sopuerta, Thomas P. Sotiriou, Nikolaos Stergioulas, Nicola Tamanini, Filippo Vernizzi, Helvi Witek, Kinwah Wu, Kent Yagi, Stoytcho S. Yazadjiev, Nicolás Yunes, Miguel Zilhão, Niayesh Afshordi, M. C. Angonin, Vishal Baibhav, Enrico Barausse, T. Barreiro, N. Bartolo, Nicolas Bellomo, Ido Ben-Dayan, Eric Bergshoeff, Sebastiano Bernuzzi, Daniele Bertacca, Swetha Bhagwat, Béatrice Bonga, Lior M. Burko, Geoffrey Compère, Giulia Cusin, A. Da Silva, Saurya Das, Claudia de Rham, Kyriakos Destounis, Emanuela Dimastrogiovanni, F. Duque, Richard Easther, Hontas Farmer, Matteo Fasiello, S. I. Fisenko, Kwinten Fransen, Jörg Frauendiener, Jonathan R. Gair, László Á. Gergely, Davide Gerosa, Leonardo Gualtieri, Wen-Biao Han, Aurélien Hees, Thomas Helfer, J. Hennig, Alexander C. Jenkins, E. Kajfasz, Nemanja Kaloper, Vladimir Karas, Bradley J. Kavanagh, Sergei A. Klioner, Savvas M. Koushiappas, Macarena Lagos, C. Le Poncin-Lafitte, Francisco S. N. Lobo, Charalampos Markakis, Prado Martín-Moruno, Carlos Martins, Sabino Matarrese, Daniel R. Mayerson, José P. Mimoso, Johannes Noller, Nelson J. Nunes, Roberto Oliveri, Giorgio Orlando, George J. Pappas, Igor Pikovski, Luigi Pilo, Jiří Podolský, Geraint Pratten, Tomislav Prokopec, H. Qi, Saeed Rastgoo, Angelo Ricciardone, Rocco Rollo, Diego Rubiera-Garcia, Olga Sergijenko, Stuart Shapiro, D. M. Shoemaker, Alessandro D. A. M. Spallicci, O. S. Stashko, Leo C. Stein, Gianmassimo Tasinato, Andrew J. Tolley, Elias C. Vagenas, Stefan Vandoren, Daniele Vernieri, Rodrigo Vicente, Toby Wiseman, V. I. Zhdanov, Miguel Zumalacárregui 
TL;DR: In this paper , the Fundamental Physics Working Group of the LISA Consortium summarizes the current topics in fundamental physics where LISA observations of gravitational waves can be expected to provide key input.
Abstract: Abstract The Laser Interferometer Space Antenna (LISA) has the potential to reveal wonders about the fundamental theory of nature at play in the extreme gravity regime, where the gravitational interaction is both strong and dynamical. In this white paper, the Fundamental Physics Working Group of the LISA Consortium summarizes the current topics in fundamental physics where LISA observations of gravitational waves can be expected to provide key input. We provide the briefest of reviews to then delineate avenues for future research directions and to discuss connections between this working group, other working groups and the consortium work package teams. These connections must be developed for LISA to live up to its science potential in these areas.

38 citations


Journal ArticleDOI
TL;DR: In this article , it was shown that a $3d$ sourced conformal Carrollian field theory has the right kinematic properties to holographically describe gravity in $4d$ asymptotically flat spacetime.
Abstract: We show that a $3d$ sourced conformal Carrollian field theory has the right kinematic properties to holographically describe gravity in $4d$ asymptotically flat spacetime. The external sources encode the leaks of gravitational radiation at null infinity. The Ward identities of this theory are shown to reproduce those of the $2d$ celestial CFT after relating Carrollian to celestial operators. This suggests a new set of interplays between gravity in asymptotically flat spacetime, sourced conformal Carrollian field theory and celestial CFT.

36 citations


Journal ArticleDOI
TL;DR: In this paper , a family of solutions of Einstein's gravity minimally coupled to an anisotropic fluid is introduced, describing asymptotically flat black holes with hair and a regular horizon.
Abstract: We introduce a family of solutions of Einstein's gravity minimally coupled to an anisotropic fluid, describing asymptotically flat black holes with ``hair'' and a regular horizon. These spacetimes can describe the geometry of galaxies harboring supermassive black holes, and are extensions of Einstein clusters to include horizons. They are useful to constrain the environment surrounding astrophysical black holes, using electromagnetic or gravitational-wave observations. We compute the main properties of the geometry, including the corrections to the ringdown stage induced by the external matter and fluxes by orbiting particles. The leading order effect to these corrections is a gravitational-redshift, but gravitational-wave propagation is affected by the galactic potential in a nontrivial way, and may be characterized with future observatories.

30 citations


Journal ArticleDOI
TL;DR: In this article , a spatially homogeneous and isotropic FLRW cosmological model in framework of the symmetric teleparallel f(Q) gravity was studied.

Journal ArticleDOI
TL;DR: In this paper , a new infinite class of gravitational observables in asymptotically anti-de Sitter space living on codimension-one slices of the geometry, the most famous of which is the volume of the maximal slice, is presented.
Abstract: We present a new infinite class of gravitational observables in asymptotically anti-de Sitter space living on codimension-one slices of the geometry, the most famous of which is the volume of the maximal slice. We show that these observables display universal features for the thermofield-double state: they grow linearly in time at late times and reproduce the switchback effect in shock wave geometries. We argue that any member of this class of observables is an equally viable candidate as the extremal volume for a gravitational dual of complexity.

Journal ArticleDOI
TL;DR: In this article , a hierarchical solution-generating technique employing the Minimum Gravitational Decoupling (MGD) method and the generalized concept of Complexity as applied to Class I spacetime for bounded compact objects in classical general relativity is presented.
Abstract: Abstract In this work, we present a hierarchical solution-generating technique employing the Minimum Gravitational Decoupling (MGD) Method and the generalized concept of Complexity as applied to Class I spacetime for bounded compact objects in classical general relativity. Starting off with an anisotropic seed solution described by Class I spacetime, we apply the MGD technique with the constraint that the effective anisotropy vanishes which leads to an isotropic model. In addition, we produce a second family of solutions in which the Complexity factor [Herrera (Phys Rev D 97:044010, 2018)] for the seed solution and its MGD counterpart are the same. We discuss the physical plausibility of both classes of solutions as candidates for physically realizable compact objects.

Journal ArticleDOI
TL;DR: In this paper , the authors considered spherically symmetric static spacetime metric with anisotropic matter contents under well-known non-commutative distributions known as Gaussian and Lorentzian distributions with an extra condition of permitting conformal killing vectors (CKV).

Journal ArticleDOI
TL;DR: In this paper , the Page curve of an eternal Reissner-Nordstrabaom black hole was obtained in the presence of higher derivative terms in four dimensions, and the authors showed that after the Page time, entanglement entropy of the Hawking radiation in both the cases reached a constant value which is the twice of the Bekenstein-Hawking entropy.
Abstract: We obtain the Page curves of an eternal Reissner-Nordstr\"om black hole in the presence of higher derivative terms in four dimensions. We consider two cases: gravitational action with general ${\cal O}(R^2)$ terms plus Maxwell term and Einstein-Gauss-Bonnet gravity plus Maxwell term. In both the cases entanglement entropy of the Hawking radiation in the absence of island surface is increasing linearly with time. After including contribution from the island surface, we find that after the Page time, entanglement entropy of the Hawking radiation in both the cases reaches a constant value which is the twice of the Bekenstein-Hawking entropy of the black hole and we obtain the Page curves. We find that Page curves appear at later or earlier time when the Gauss-Bonnet coupling increases or decreases. Further, scrambling time of Reissner-Nordstr\"om is increasing or decreasing depending upon whether the correction term (coming from ${\cal O}(R^2)$ terms in the gravitational action) is increasing or decreasing in the first case whereas scrambling time remains unaffected in the second case (Einstein-Gauss-Bonnet gravity case). As a consistency check, in the limit of vanishing GB coupling we obtain the Page curve of the Reissner-Nordstr\"om black hole obtained in arXiv:2101.06867.

Journal ArticleDOI
TL;DR: In this article , the relativistic classical scattering of two point-charges, at sixth order in the charges (analogous to 3PM order in gravity), is studied. But the authors focus on the effects of radiative effects on the trajectories of the two points.
Abstract: As recent work continues to demonstrate, the study of relativistic scattering processes leads to valuable insights and computational tools applicable to the relativistic bound-orbit two-body problem. This is particularly relevant in the post-Minkowskian approach to the gravitational two-body problem, where the field has only recently reached a full description of certain physical observables for scattering orbits, including radiative effects, at the third post-Minkowskian (3PM) order. As an historically instructive simpler example, we consider here the analogous problem in electromagnetism in flat spacetime. We compute the changes in linear momentum of each particle and the total radiated linear momentum, in the relativistic classical scattering of two point-charges, at sixth order in the charges (analogous to 3PM order in gravity). We accomplish this here via direct iteration of the classical equations of motion, while making comparisons where possible to results from quantum scattering amplitudes, with the aim of contributing to the elucidation of conceptual issues and scalability on both sides. We also discuss further extensions to radiative quantities of recently established relations, which analytically continue certain observables from the scattering regime to the regime of bound orbits, applicable for both the electromagnetic and gravitational cases.

Journal ArticleDOI
TL;DR: In this article , two Schrodinger-like equations with spin-dependent effective potentials were coupled for parity-violating corrections, and this coupling affects the quasinormal modes even at linear order in the higher-derivative corrections, due to their isospectrality in general relativity.
Abstract: We study gravitational perturbations of slowly rotating black holes in a general effective-field-theory extension of general relativity that includes up to eight-derivative terms. We show that two Schr\"odinger-like equations with spin-dependent effective potentials govern the odd- and even-parity master variables. These equations are coupled for parity-violating corrections, and this coupling affects the quasinormal modes even at linear order in the higher-derivative corrections, due to their isospectrality in general relativity. We provide results for the shifts in the fundamental quasinormal mode frequencies at linear order in the spin, which we expect to be valuable for high-precision phenomenology through future gravitational wave observations.

Journal ArticleDOI
TL;DR: In this article , a matrix integral with the insertion of a Gaussian with variance σ 2 , centered around a matrix, is considered, and a gravity theory with a fixed boundary Hamiltonian is presented.
Abstract: We present a gravitational theory that interpolates between JT gravity, and a gravity theory with a fixed boundary Hamiltonian. For this, we consider a matrix integral with the insertion of a Gaussian with variance $\sigma^2$, centered around a matrix $\textsf{H}_0$. Tightening the Gaussian renders the matrix integral less random, and ultimately it collapses the ensemble to one Hamiltonian $\textsf{H}_0$. This model provides a concrete setup to study factorization, and what the gravity dual of a single member of the ensemble is. We find that as $\sigma^2$ is decreased, the JT gravity dilaton potential gets modified, and ultimately the gravity theory goes through a series of phase transitions, corresponding to a proliferation of extra macroscopic holes in the spacetime. Furthermore, we observe that in the Efetov model approach to random matrices, the non-averaged factorizing theory is described by one simple saddle point.

Journal ArticleDOI
TL;DR: In this paper , the authors consider a theory which modifies general relativity by introducing a scalar field coupled to a parity-violating curvature term known as dynamical Chern-Simons gravity and find strong evidence that these rotating black holes are linearly stable.
Abstract: The detection of gravitational waves from compact binary mergers by the LIGO/Virgo Collaboration has, for the first time, allowed us to test relativistic gravity in its strong, dynamical, and nonlinear regime, thus opening a new arena to confront general relativity (and modifications thereof) against observations. We consider a theory which modifies general relativity by introducing a scalar field coupled to a parity-violating curvature term known as dynamical Chern-Simons gravity. In this theory, spinning black holes are different from their general relativistic counterparts and can thus serve as probes to this theory. We study linear gravito-scalar perturbations of black holes in dynamical Chern-Simons gravity at leading order in spin and (i) obtain the perturbed field equations describing the evolution of the perturbed gravitational and scalar fields, (ii) numerically solve these equations by direct integration to calculate the quasinormal mode frequencies for the dominant and higher multipoles and tabulate them, (iii) find strong evidence that these rotating black holes are linearly stable, and (iv) present general fitting functions for different multipoles for gravitational and scalar quasinormal mode frequencies in terms of spin and Chern-Simons coupling parameter. Our results can be used to validate the ringdown of small-spin remnants of numerical relativity simulations of black hole binaries in dynamical Chern-Simons gravity and pave the way towards future tests of this theory with gravitational wave ringdown observations.

Journal ArticleDOI
TL;DR: In this article , the role of decoupling to isotropize the anisotropic solution of Einstein's field equations in the context of the complete geometric deformation (CGD) approach and its influence on the complexity factor introduced by L. Herrera (Phys. Rev.
Abstract: In the present paper, we discuss the role of gravitational decoupling to isotropize the anisotropic solution of Einstein's field equations in the context of the complete geometric deformation (CGD) approach and its influence on the complexity factor introduced by L. Herrera (Phys. Rev. D 97, 044010 (2018)) in the static self-gravitating system. Moreover, we also proposed a simple and effective technique to generate new solutions for self-gravitating objects via CGD approach by using two systems with the same complexity factor and vanishing complexity factor proposed by Casadio et al. Eur. Phys. J. C 79, 826 (2019). The effect of decoupling constant and the compactness on the complexity factor have been also analyzed for the obtained solutions.

Journal ArticleDOI
TL;DR: In this article , the authors study the role of complexity on static and spherically symmetric self-gravitating systems in the gravitational decoupling background and propose novel classes of solutions.
Abstract: In this paper, we study novel classes of solutions characterizing the role of complexity on static and spherically symmetric self‐gravitating systems proposed by L. Herrera (Phys Rev D 97: 044010, 2018) in the gravitational decoupling background. We start by considering the minimal geometric deformation approach as a ground‐breaking tool for generating new physically viable models for anisotropic matter distributions by exploiting the Buchdahl and Tolman models. In both models, all solutions show similar results with a slight change in their magnitude for a non‐vanishing complexity factor i.e., 0≤β<1$0\le \beta < 1$ , where β is a decoupling constant. However, under vanishing complexity factor i.e., β=1$\beta = 1$ , the minimally deformed anisotropic Buchdahl model yielded a constant density isotropic fluid distribution and anisotropic matter distribution becomes an isotropic fluid matter distribution without invoking any isotropy requirement. On the other hand, Tolman model possesses an increasing pressure when the complexity factor vanishes. Furthermore, we also extend our findings by calculating the mass‐complexity factor relationship for both presented models, revealing that the mass is larger for small values of the decoupling constant β and the complexity factor YTF$Y_{TF}$ .

Journal ArticleDOI
TL;DR: The relation between thermal transport and gravity was highlighted in the seminal work by Luttinger in 1964, and has been extensively developed to understand thermal transport as discussed by the authors , and the concepts that relate thermal transport, the geometry of space-time and quantum field theory anomalies.

Journal ArticleDOI
TL;DR: In this article , a massive body is used as an amplifying mediator of the gravitational interaction between two test systems, which results in an effective interaction that grows with the mass of the mediator, independent of its initial state and therefore its temperature.
Abstract: In 1957 Feynman suggested that the quantum or classical character of gravity may be assessed by testing the gravitational interaction due to source masses in superposition. However, in all proposed experimental realizations using matter-wave interferometry, the extreme weakness of this interaction requires pure initial states with extreme squeezing to achieve measurable effects of nonclassical interaction for reasonable experiment durations. In practice, the systems that can be prepared in such nonclassical states are limited to small masses, which in turn limits the strength of their interaction. Here we address this key challenge-the weakness of gravitational interaction-by using a massive body as an amplifying mediator of gravitational interaction between two test systems. Our analysis shows that this results in an effective interaction between the two test systems that grows with the mass of the mediator, is independent of its initial state and, therefore, its temperature. This greatly reduces the requirement on the mass and degree of delocalization of the test systems and, while still highly challenging, brings experiments on gravitational source masses a step closer to reality.

Journal ArticleDOI
01 Feb 2022-1
TL;DR: In this paper , a comparative analysis of ten types of gravity search algorithms that modify the three parameters of optimum, speed and position is conducted on two sets of benchmark types, namely standard functions and issues belonging to different types such as CEC2015 functions, univocal, multimodal and unrestricted optimization functions.
Abstract: Gravitational search algorithm is a naturally occurring algorithm based on Newton's mathematical model of the law of gravitation and motion. Over the course of a decade, researchers have provided many variants of the gravitational search algorithm by modifying its parameters to effectively solve complex optimization problems. This paper conducts a comparative analysis of ten types of gravity search algorithms that modify the three parameters of optimum, speed and position. Tests are conducted on two sets of benchmark types, namely standard functions and issues belonging to different types such as CEC2015 functions, univocal, multimodal and unrestricted optimization functions. Performance comparison is evaluated and statistically validated based on the average exercise value and concentration graph. In trials, IGSA has achieved excellent accuracy through a balanced trade between exploration and exploitation. Furthermore, three negative breast cancer datasets were considered to analyze the efficacy of GSA variants for the black section. Different performance analyzes were performed based on both quality and quantity with the integrated jacquard index as a performance measure. Tests confirm that the IGSA based method worked better than other methods.

Journal ArticleDOI
TL;DR: By considering graviton-photon scattering in the standard model, this article argued that the low-energy theory can be used to put constraints on the UV behavior of the gravitational scattering amplitudes.
Abstract: S-matrix bootstrap and positivity bounds are usually viewed as constraints on low-energy theories imposed by the requirement of a standard UV completion. By considering graviton-photon scattering in the standard model, we argue that the low-energy theory can be used to put constraints on the UV behavior of the gravitational scattering amplitudes.

Journal ArticleDOI
TL;DR: In this paper , a modified SSS matrix model with dynamical end-of-the-world branes is presented, and the Euclidean path integral summing is computed over topologies including dynamical branes.
Abstract: A bstract We study Jackiw-Teitelboim gravity with dynamical end of the world branes in asymptotically nearly AdS 2 spacetimes. We quantize this theory in Lorentz signature, and compute the Euclidean path integral summing over topologies including dynamical branes. The latter will be seen to exactly match with a modification of the SSS matrix model. The resolution of UV divergences in the gravitational instantons involving the branes will lead us to understand the matrix model interpretation of the Wilsonian effective theory perspective on the gravitational theory. We complete this modified SSS matrix model nonperturbatively by extending the integration contour of eigenvalues into the complex plane. Furthermore, we give a new interpretation of other phases in such matrix models. We derive an effective W (Φ) dilaton gravity, which exhibits similar physics semiclassically. In the limit of a large number of flavors of branes, the effective extremal entropy S 0 , eff has the form of counting the states of these branes.

Journal ArticleDOI
TL;DR: In this article , it was shown that there are wormhole solutions which are asymmetric relative the throat and endowed by smooth gravitational and matter fields, thereby being free from all the above problems.
Abstract: Bl\'azquez-Salcedo et al. [Phys. Rev. Lett. 126, 101102 (2021)] obtained asymptotically flat traversable wormhole solutions in the Einstein-Dirac-Maxwell theory without using phantom matter. The normalizable numerical solutions found therein require a peculiar behavior at the throat: the mirror symmetry relatively the throat leads to the nonsmoothness of gravitational and matter fields. In particular, one must postulate changing of the sign of the fermionic charge density at the throat, requiring coexistence of particle and antiparticles without annihilation and posing a membrane of matter at the throat with specific properties. Apparently this kind of configuration could not exist in nature. We show that there are wormhole solutions, which are asymmetric relative the throat and endowed by smooth gravitational and matter fields, thereby being free from all the above problems. This indicates that such wormhole configurations could also be supported in a realistic scenario.

Journal ArticleDOI
TL;DR: The MICROSCOPE mission as mentioned in this paper aimed to test the weak equivalence principle (WEP) to a precision of 10 − 15 , where two masses of different compositions (titanium and platinum alloys) are placed on a quasi-circular trajectory around the Earth.
Abstract: Abstract The MICROSCOPE mission aimed to test the weak equivalence principle (WEP) to a precision of 10 −15 . The WEP states that two bodies fall at the same rate on a gravitational field independently of their mass or composition. In MICROSCOPE, two masses of different compositions (titanium and platinum alloys) are placed on a quasi-circular trajectory around the Earth. They are the test-masses of a double accelerometer. The measurement of their accelerations is used to extract a potential WEP violation that would occur at a frequency defined by the motion and attitude of the satellite around the Earth. This paper details the major drivers of the mission leading to the specification of the major subsystems (satellite, ground segment, instrument, orbit…). Building upon the measurement equation, we derive the objective of the test in statistical and systematic error allocation and provide the mission’s expected error budget.

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TL;DR: In this article , the consequences of extra curvature terms mediated from f(R, T, Q) theory on the formation of scalar functions and their importance in the study of populations who are crowded with regular relativistic objects are explored.
Abstract: The aim of this paper is to explore the consequences of extra curvature terms mediated from f(R, T, Q) (where Q ≡ R μ ν T μ ν ) theory on the formation of scalar functions and their importance in the study of populations who are crowded with regular relativistic objects. For this purpose, we model our system comprising of non-rotating spherical geometry formed due to gravitation of locally anisotropic and radiating sources. After considering a particular f(R, T, Q) model, we form a peculiar relation among Misner-Sharp mass, tidal forces, and matter variables. Through structure scalars, we have modeled shear, Weyl, and expansion evolutions equations. The investigation for the causes of the irregular distribution of energy density is also performed with and without constant curvature conditions. It is deduced that our computed one of the f(R, T, Q) structure scalars (Y T ) has a vital role to play in understanding celestial mechanisms in which gravitational interactions cause singularities to emerge.

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TL;DR: In this article , an initial value formulation of the WQFT approach to the classical two-body problem in general relativity is presented, where the Schwinger-Keldysh (in-in) formalism leads to purely retarded propagators in the evaluation of observables.
Abstract: A bstract We exhibit an initial-value formulation of the worldline quantum field theory (WQFT) approach to the classical two-body problem in general relativity. We show that the Schwinger-Keldysh (in-in) formalism leads to purely retarded propagators in the evaluation of observables in the WQFT. Integration technology for retarded master integrals is introduced at third post-Minkowskian (3PM) order. As an application we compute the complete radiation-reacted impulse and radiated four momentum for the scattering of two non-spinning neutron stars including tidal effects at 3PM order, as well as the leading (2PM) far-field gravitational waveform.