Article
Physics, Multidisciplinary
Arjun Kar, Lampros Lamprou, Charles Marteau, Felipe Rosso
Summary: This study constructs a Hermitian random matrix model to provide a stable nonperturbative completion of Cangemi-Jackiw gravity theory and computes observables in flat space quantum gravity to characterize the Bondi Hamiltonian spectrum. The implications of these results for the flat space S-matrix and black holes are discussed.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Multidisciplinary
Peng Yin, Xiaobin Zhao, Yuxiang Yang, Yu Guo, Wen-Hao Zhang, Gong-Chu Li, Yong-Jian Han, Bi-Heng Liu, Jin-Shi Xu, Giulio Chiribella, Geng Chen, Chuan-Feng Li, Guang-Can Guo
Summary: This article presents a photonic implementation of a quantum metrology protocol that surpasses the Heisenberg limit by probing two groups of independent processes in a superposition of two alternative causal orders. The method is able to estimate a geometric phase associated with two sets of N displacements with an error that falls quadratically with N.
Article
Physics, Multidisciplinary
L. Asprea, A. Bassi, H. Ulbricht, G. Gasbarri
Summary: The paper presents a general master equation describing the quantum dynamics of a scalar bosonic field interacting with an external weak and stochastic gravitational field, predicting decoherence in both position and energy momentum. By taking appropriate limits, the master equation reproduces and generalizes previous results in the literature. The study also estimates the effect of gravitational decoherence in atom interferometers, offering a straightforward method for assessing the magnitude of the effect.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Multidisciplinary
Qasem Exirifard, Eric Culf, Ebrahim Karimi
Summary: This study explores how the curvature of spacetime geometry affects the propagation of information carriers and emphasizes the significance of gravitational distortion on Earth-to-satellite communication. It highlights the need to pre- or post-correct this distortion at the sender or receiver to retrieve the information.
COMMUNICATIONS PHYSICS
(2021)
Article
Astronomy & Astrophysics
A. Bochniak, A. Sitarz
Summary: We have derived a perturbative formula for the direct interaction between two four-dimensional geometries and presented an explicit potential expression up to the third order perturbation based on the spectral action principle. The leading terms of the interaction are expressed as polynomials of the invariants of the two metrics and compared with bimetric gravity models.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
K. Sravan Kumar, Shubham Maheshwari, Anupam Mazumdar, Jun Peng
Summary: The study explores the possibility of realizing a cosmological bouncing solution in a non-local gravity theory in an anisotropic but homogeneous background, showcasing the behavior of anisotropic shear and the matter components required for the bounce. It is found that k-matter exerts anisotropic pressures and the bouncing solution can satisfy positivity of energy density while avoiding ghost/tachyonic modes in the de Sitter phase in non-local gravity.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Zhaoyi Xu
Summary: In this research, the analytical solution of semi-classical rotating black holes in loop quantum gravity theory is obtained, and the expression for the previously unknown function H is derived, providing a foundation for the study of rotating black holes.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Enrique Alvarez, Jesus Anero, Eduardo Velasco-Aja
Summary: In this paper, the physical effects of deforming the usual Einstein-Hilbert lagrangian with the Goroff-Sagnotti counterterm (the first which is nonvanishing on shell) are studied. Only spherically symmetric solutions are discussed. The non-solution of Schwarzschild's spacetime to the corresponding equations of motion and the validity of Birkhoff's theorem are analyzed, and some consequences are worked out.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Alejandro Jimenez-Cano, Francisco Jose Maldonado Torralba
Summary: This work examines the stability of the torsion and nonmetricity tensors in the general quadratic metric-affine Lagrangian in 4 dimensions. The study focuses on determining the conditions under which the spin-1 modes associated with these vectors can propagate safely along with the graviton. The research findings significantly reduce the parameter space of the quadratic curvature part from 16 to 5 parameters.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Zhaoyi Xu
Summary: In this paper, an expression for the unknown function H in the semi-classical rotating black holes in loop quantum gravity theory is obtained, providing a well-expressed space-time line element and a basis for further study on rotating black holes.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Antonio De Felice, Kei-ichi Maeda, Shinji Mukohyamaa, Masroor C. Pookkillatha
Summary: We study the collapse of a spherically symmetric dust cloud in the VCDM gravitational theory and find that it corresponds to a specific foliation of the Oppenheimer-Snyder solution in general relativity. The resulting collapse leads to a static configuration with a vanishing lapse function at a radius inside the apparent horizon. This implies the need for a UV completion to describe the physics inside the resulting black hole.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Shinji Mukohyama, Vicharit Yingcharoenrat
Summary: This study formulates the Effective Field Theory (EFT) of perturbations within scalar-tensor theories on an inhomogeneous background. A set of consistency relations imposed by the invariance of the EFT under the 3d spatial diffeomorphism is found. This EFT can be applied generically to any in-homogeneous background metric as long as the scalar profile is everywhere timelike.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
C. Gomes, O. Bertolami
Summary: In this study, we restrict the viable models of Horndeski gravity, formulated as the equivalent Generalised Galileon version, using the Witten positive energy theorem. The analysis reveals that the free function G(3)(phi, X) in the Lagrangian is solely dependent on the scalar field, G(3)(phi), and establishes relationships among the free functions. Additionally, stability criteria such as gravity attractiveness and Dolgov-Kawasacki instability are examined, and cosmological applications are discussed.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Katsuki Aoki, Francesco Di Filippo, Shinji Mukohyama
Summary: The study demonstrates that the cuscuton/VCDM theory cannot be equivalent to general relativity through field redefinition, but rather differs from general relativity in vacuum.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Shaswata Chowdhury, Tapobrata Sarkar
Summary: The study investigates the effects of modified gravity beyond Horndeski theory in the interior of a population II star, finding that reduced gravity may result in decreased luminosity and increased radius of the star, but some effects are reversed near the core. The model provides a constraint on the modified gravity parameter within its limitations.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Claudia de Rham, Scott Melville, Johannes Noller
Summary: Positivity bounds have been used to constrain scalar-tensor theories of dark energy, but coupling to matter fields has played a limited role. Demanding positivity when including interactions with standard matter fields leads to further constraints on the dark energy parameter space. Implementing these bounds as theoretical priors affects cosmological parameter constraints and shows that gravitational waves must travel superluminally on cosmological backgrounds in a standard UV completion.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Physics, Multidisciplinary
Yiqi Xie, Jun Zhang, Hector O. Silva, Claudia de Rham, Helvi Witek, Nicolas Yunes
Summary: In general theories of gravity, the spacetime of a stationary, axisymmetric, and asymptotically flat solution must be circular if the solution can be perturbatively obtained from a solution in the general relativity limit. This result applies to a wide range of gravitational theories including arbitrary scalars and vectors, with nonstandard kinetic terms and nonminimal couplings to gravity treated perturbatively.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Multidisciplinary
Lasma Alberte, Claudia de Rham, Sumer Jaitly, Andrew J. Tolley
Summary: The low-energy theory can be used to constrain the UV behavior of gravitational scattering amplitudes by considering graviton-photon scattering in the standard model.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Particles & Fields
Mariana Carrillo Gonzalez, Claudia de Rham, Andrew J. Tolley
Summary: This paper demonstrates the extension of amplitude methods beyond standard calculations in General Relativity for constructing gravitational waveforms, as well as the potential of conformal coupling matter and the application of gravitational helicity-0 mode. The study shows the complexities in the matching procedure and the non-trivial dependence on energy/momentum of scattered particles in the computation of conservative potential and scattering angle for binary systems.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Astronomy & Astrophysics
Claudia de Rham, Sebastian Garcia-Saenz, Lavinia Heisenberg, Victor Pozsgay
Summary: Proca-Nuevo is a non-linear theory of a massive spin-1 field that can be extended by adding operators from the Generalized Proca class. This extension maintains the primary constraint necessary for consistency and allows for interpolation between Generalized Proca operators and Proca-Nuevo ones. When mixed with gravity, the constraint is broken in a Planck scale suppressed way. The theory can be covariantized in models that allow for consistent and ghost-free cosmological solutions, and it accurately describes the dynamics and dispersion relations of perfect fluid matter. Specific solutions exhibit hot Big Bang scenarios with a late-time self-accelerating epoch, where gravitational waves behave similarly to General Relativity.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Physics, Multidisciplinary
Claudia de Rham, Andrew J. Tolley, Jun Zhang
Summary: In this article, we investigate the effective field theory of gravity around black holes and find that the coefficients of the dimension-8 operators are tightly constrained by causality considerations. These constraints are more stringent than previously derived causality and positivity bounds, suggesting that the effects of a single dimension-8 operator cannot be observed while maintaining causality. We also identify the regime where the generic dimension-8 and lower order operators can potentially be observable while preserving causality.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Particles & Fields
Calvin Y-R Chen, Claudia de Rham, Aoibheann Margalit, Andrew J. Tolley
Summary: This study distinguishes between the concepts of asymptotic causality and infrared causality in gravitational effective field theories, and shows that the latter provides constraints consistent with gravitational positivity bounds. By investigating the scattering of gravitational waves in a spherically symmetric background, the researchers demonstrate the apparent time advances observed in the truncated effective theory can be resolved by properly identifying the regime of validity. The results indicate that neither infrared nor asymptotic causality are violated in Einstein-Gauss-Bonnet gravity, regardless of the scale.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Review
Physics, Particles & Fields
K. G. Arun, Enis Belgacem, Robert Benkel, Laura Bernard, Emanuele Berti, Gianfranco Bertone, Marc Besancon, Diego Blas, Christian G. Bohmer, Richard Brito, Gianluca Calcagni, Alejandro Cardenas-Avendano, Katy Clough, Marco Crisostomi, Valerio De Luca, Daniela Doneva, Stephanie Escoffier, Jose Maria Ezquiaga, Pedro G. Ferreira, Pierre Fleury, Stefano Foffa, Gabriele Franciolini, Noemi Frusciante, Juan Garcia-Bellido, Carlos Herdeiro, Thomas Hertog, Tanja Hinderer, Philippe Jetzer, Lucas Lombriser, Elisa Maggio, Michele Maggiore, Michele Mancarella, Andrea Maselli, Sourabh Nampalliwar, David Nichols, Maria Okounkova, Paolo Pani, Vasileios Paschalidis, Alvise Raccanelli, Lisa Randall, Sebastien Renaux-Petel, Antonio Riotto, Milton Ruiz, Alexander Saffer, Mairi Sakellariadou, Ippocratis D. Saltas, B. S. Sathyaprakash, Lijing Shao, Carlos F. Sopuerta, Thomas P. Sotiriou, Nikolaos Stergioulas, Nicola Tamanini, Filippo Vernizzi, Helvi Witek, Kinwah Wu, Kent Yagi, Stoytcho Yazadjiev, Nicolas Yunes, Miguel Zilhao, Niayesh Afshordi, Marie-Christine Angonin, Vishal Baibhav, Enrico Barausse, Tiago Barreiro, Nicola Bartolo, Nicola Bellomo, Ido Ben-Dayan, Eric A. Bergshoeff, Sebastiano Bernuzzi, Daniele Bertacca, Swetha Bhagwat, Beatrice Bonga, Lior M. Burko, Geoffrey Compere, Giulia Cusin, Antonio da Silva, Saurya Das, Claudia de Rham, Kyriakos Destounis, Ema Dimastrogiovanni, Francisco Duque, Richard Easther, Hontas Farmer, Matteo Fasiello, Stanislav Fisenko, Kwinten Fransen, Jorg Frauendiener, Jonathan Gair, Laszlo Arpad Gergely, Davide Gerosa, Leonardo Gualtieri, Wen-Biao Han, Aurelien Hees, Thomas Helfer, Jorg Hennig, Alexander C. Jenkins, Eric Kajfasz, Nemanja Kaloper, Vladimir Karas, Bradley J. Kavanagh, Sergei A. Klioner, Savvas M. Koushiappas, Macarena Lagos, Christophe Le Poncin-Lafitte, Francisco S. N. Lobo, Charalampos Markakis, Prado Martin-Moruno, C. J. A. P. Martins, Sabino Matarrese, Daniel R. Mayerson, Jose P. Mimoso, Johannes Noller, Nelson J. Nunes, Roberto Oliveri, Giorgio Orlando, George Pappas, Igor Pikovski, Luigi Pilo, Geraint Pratten, Tomislav Prokopec, Hong Qi, Saeed Rastgoo, Angelo Ricciardone, Rocco Rollo, Diego Rubiera-Garcia, Olga Sergijenko, Stuart Shapiro, Deirdre Shoemaker, Alessandro Spallicci, Oleksandr Stashko, Leo C. Stein, Gianmassimo Tasinato, Andrew J. Tolley, Elias C. Vagenas, Stefan Vandoren, Daniele Vernieri, Rodrigo Vicente, Toby Wiseman, Valery Zhdanov, Miguel Zumalacarregui
Summary: This white paper summarizes the importance of LISA in the field of fundamental physics and discusses future research directions and connections with other working groups.
LIVING REVIEWS IN RELATIVITY
(2022)
Article
Physics, Particles & Fields
Claudia de Rham, Laura Engelbrecht, Lavinia Heisenberg, Alice Luescher
Summary: Assuming unitarity, locality, causality, and Lorentz invariance, this paper derives new constraints on the effective field theory coefficients for the Generalized Proca and Proca Nuevo massive vector models, while finding interesting analogues between the two models.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Astronomy & Astrophysics
Tessa Baker, Enrico Barausse, Anson Chen, Claudia de Rham, Mauro Pieroni, Gianmassim Tasinto
Summary: Effective field theories (EFT) of dark energy (DE) are limited by constraints on the propagation speed of gravitational waves (GW) but can still be valid at scales beyond the EFT description. Lower frequency observations by LISA would be harder to escape, while a joint observation by LISA and a terrestrial interferometer could constrain the speed of light and gravitons to within 10^-15. Multiband GW observations can therefore effectively constrain DE scenarios based on EFT.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Physics, Particles & Fields
Claudia de Rham, Sebastian Garcia-Saenz, Lavinia Heisenberg, Victor Pozsgay, Xinmiao Wang
Summary: It was recently suggested that half degrees of freedom could exist in Lorentz and parity invariant field theories. A specific example, the non-linear Proca field theory called Proca-Nuevo, is used to illustrate this argument. Through the Lagrangian and Hamiltonian approaches, we present two proofs that this theory possesses a pair of second class constraints, resulting in D - 1 degrees of freedom in D spacetime dimensions, which is consistent with a Proca model. Our proofs are explicit and straightforward in two dimensions and we discuss their generalization to any number of dimensions. We also clarify why local Lorentz and parity invariant field theories cannot have half degrees of freedom.
JOURNAL OF HIGH ENERGY PHYSICS
(2023)
Article
Astronomy & Astrophysics
Mariana Carrillo Gonzalez, Claudia de Rham, Victor Pozsgay, Andrew J. Tolley
Summary: This paper investigates the constraints imposed by low energy causality alone on EFTs and finds that these constraints are in agreement with the compact positivity constraints obtained from scattering amplitude dispersion relations.
Article
Astronomy & Astrophysics
Claudia de Rham, Lavinia Heisenberg, Ankip Kumar, Jann Zosso
Summary: The article discusses the construction and nature of general derivative self-interactions for a massive Proca field. It is found that despite differences in scattering amplitudes, the high energy behavior of Proca-Nuevo and generalized Proca is the same when quantum corrections are taken into account.
Article
Astronomy & Astrophysics
Lasma Alberte, Claudia de Rham, Sumer Jaitly, Andrew J. Tolley
Summary: Positivity bounds applied to U(1) gauge theory reveal violations that can be rectified by introducing new physics at a low scale Lambda(new), contrasting previous studies that focused on different applications. The introduction of a small amount of negativity is conjectured to be allowed and not conflict with standard UV completions.
