Article
Astronomy & Astrophysics
Vijay Nenmeli, S. Shankaranarayanan, Vasil Todorinov, Saurya Das
Summary: This study utilizes the Generalized Uncertainty Principle to model features of quantum gravity and explores the applications of Stelle gravity in cosmology. It shows that Stelle gravity can be considered as a classical manifestation of maximum momentum and the GUP. Strong constraints on the GUP parameter are obtained from CMB observations, providing both lower and upper bounds.
Article
Astronomy & Astrophysics
Jisuke Kubo, Jeffrey Kuntz, Jonas Rezacek, Philipp Saake
Summary: We investigate the effects of gravitational degrees of freedom on inflationary parameters in a generic model of quadratic gravity coupled to a single scalar. Our findings show that quantum corrections from the massive spin-2 ghost contribute significantly to the effective inflationary potential, enabling the spontaneous breakdown of global scale invariance without the need for additional scalar fields. We compute inflationary parameters and compare them to well-known inflationary models, finding that they fit within the constraints set by the Planck and BICEP/Keck collaborations.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
David Brizuela, Irene de Leon
Summary: A geometrodynamical quantization of an inflationary universe is considered to estimate quantum-gravity effects for the primordial perturbations, with results showing that both self-interaction and back-reaction from other modes provide corrections of the same order of magnitude to the power spectrum. These quantum-gravity effects introduce characteristic scale-dependence on the expression of the power spectrum.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
A. Bonanno, S. Silveravalle
Summary: The study investigates the effect of different terms in quadratic theories of gravity on the characteristics of the gravitational field, suggesting that variations in these terms can lead to deviations from standard General Relativity. By analyzing the impact of quadratic corrections on self-gravitating fluid properties, the research provides insights into the potential for detecting deviations from traditional gravitational theories through ambiguity in mass definitions.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Zhong-Wen Feng, Xia Zhou, Shi-Qi Zhou
Summary: The paper investigates the mechanism of gravitational baryogenesis for generating baryon asymmetry in the early Universe. It is found that using a higher-order generalized uncertainty principle (GUP) can break the thermal equilibrium of the Universe and produce baryon asymmetry. The results of the study satisfy Sakharov's conditions, demonstrating the feasibility of explaining baryon asymmetry within the framework of higher-order GUP.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Alexander F. Jercher, Daniele Oriti, Andreas G. A. Pithis
Summary: In this study, we investigate the cosmological sector of the Lorentzian Barrett-Crane model and find that it exhibits homogeneous and isotropic cosmological dynamics similar to the SU(2)-based EPRL model. By using continuous SL(2, C) representations, we derive generalized Friedmann equations that show a quantum bounce and can reproduce all the features of the cosmological dynamics in the EPRL model.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Fabio M. Mele, Johannes Muench, Stratos Pateloudis
Summary: In this paper, the authors continue the analysis of the effective model of quantum Schwarzschild black holes. They find that the central singularity is resolved in the quantum-corrected spacetime and quantum effects become relevant at a mass-independent curvature scale. They focus on the thermodynamic properties of the effective polymer black hole and analyze the quantum corrections as functions of black and white hole masses. The study reveals an extremal minimal-sized configuration characterized by vanishing temperature and entropy. For large masses, the classical results are recovered and quantum corrections are negligible.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Saurya Das, S. Shankaranarayanan, Vasil Todorinov
Summary: A recent study establishes the correspondence between the Generalized Uncertainty Principle (GUP) and Modified theories of gravity, particularly Stelle gravity. The study investigates the implications of this correspondence for inflation and cosmological observables by evaluating the power spectrum of perturbations using two different methods. By utilizing PLANCK observations, the GUP parameter gamma(0) is determined and its value is used to study the effects of quantum gravity on the power spectrum of primordial gravitational waves and their detectability in future detectors.
Article
Astronomy & Astrophysics
Daniele Oriti, Xiankai Pang
Summary: The analysis of emergent cosmological dynamics in mean field hydrodynamics of quantum gravity condensates reveals accelerated expansion of the universe at both early and late times. Although it does not support a compelling inflationary scenario in the early universe, it naturally produces a phantom-like dark energy dynamics at late times, which crosses the phantom divide and avoids any Big Rip singularity, approaching a de Sitter universe asymptotically.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Multidisciplinary Sciences
Giovanni Amelino-Camelia, Giacomo D'Amico, Fabrizio Fiore, Simonetta Puccetti, Michele Ronco
Summary: Recent studies have shown preliminary but intriguing statistical evidence of in vacuo dispersion in gamma-ray bursts, with consistent results found by extending the energy range down to 5 GeV.
Article
Astronomy & Astrophysics
Pasquale Bosso, Giuseppe Gaetano Luciano, Luciano Petruzziello, Fabian Wagner
Summary: This study examines various arguments in quantum gravity, both model-dependent and model-independent, which suggest a modification of Heisenberg's uncertainty principle near the Planck scale. This modification is attributed to the existence of a minimal length. The study critically reviews the conceptual shortcomings of the underlying framework and recent developments in the field. It addresses issues such as relativity, field theory generalizations, the classical limit, and the application to composite systems. Additionally, the study comments on the use of heuristic arguments and presents a comprehensive list of constraints on the model parameter ss, considering their derivation rigor and potential problems with composites.
CLASSICAL AND QUANTUM GRAVITY
(2023)
Article
Physics, Multidisciplinary
Sofia Qvarfort, Dennis Raetzel, Stephen Stopyra
Summary: In this study, we derive the best possible bounds on Yukawa- and chameleon-like modifications to the Newtonian gravitational potential using a cavity optomechanical quantum sensor. We take into account the size of the optomechanical probe and investigate the screening effect when both the source and probe are spherical.
NEW JOURNAL OF PHYSICS
(2022)
Article
Astronomy & Astrophysics
Damiano Anselmi
Summary: This study investigates primordial cosmology with two scalar fields participating in inflation, revealing the existence of an asymptotically de Sitter cosmic RG flow in two couplings. The importance of quantum gravity theory's predictiveness and the role of RG invariance are highlighted.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Naritaka Oshita, Niayesh Afshordi, Shinji Mukohyama
Summary: This study investigates the ringdown waveform and reflectivity of a Lifshitz scalar field around a fixed Schwarzschild black hole, finding that Lifshitz waves scattered by the black hole exhibit superradiance due to Lorentz breaking terms leading to superluminal propagation. This can allow Lifshitz waves to carry additional positive energy to infinity while leaving negative energy inside the Killing horizon, similar to the Penrose process in Kerr spacetime. The study also observes the emergence of long-lived quasinormal modes and drastic modifications to the greybody factor of a microscopic black hole with Hawking temperature comparable to the Lifshitz energy scale.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Review
Physics, Multidisciplinary
Marieke van Beest, Jose Calderon-Infante, Delaram Mirfendereski, Irene Valenzuela
Summary: The Swampland program aims to determine the constraints that must be satisfied by an effective field theory to be consistent with a UV embedding in a quantum gravity theory. This article provides a pedagogical introduction to the most important Swampland conjectures, their connections, and their realization in string theory compactifications.
PHYSICS REPORTS-REVIEW SECTION OF PHYSICS LETTERS
(2022)
Article
Astronomy & Astrophysics
Dongdong Zhang, Jia-Rui Li, Jiaqi Yang, Yufei Zhang, Yi-Fu Cai, Wenjuan Fang, Chang Feng
Summary: We use the Ali Cosmic Microwave Background Polarization Telescope (AliCPT) to forecast the constraints on neutrino physics parameters using the Cosmic Microwave Background (CMB) temperature, E-mode polarization, and lensing spectra. Our numerical simulations show that AliCPT can achieve a precision of sigma(N (eff)) = 0.56 and M (nu) < 1.10 eV (95% CL.) for the first year of observation, based on TT, TE, EE, and CMB lensing power spectra. We also investigate how instrumental parameters such as noise level, FWHM, and sky coverage affect these constraints on neutrino parameters.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Maria Mylova, Jackson Levi Said, Emmanuel N. Saridakis
Summary: This paper constructs the effective field theory (EFT) of the teleparallel equivalent of general relativity (TEGR). The EFT contains more terms compared to the EFT of general relativity (GR) and possesses minor but non-zero differences. However, these differences are suppressed by a heavy mass scale ? and may not be measurable in future experiments and observations.
CLASSICAL AND QUANTUM GRAVITY
(2023)
Article
Astronomy & Astrophysics
Shreya Banerjee, Sayantani Bera, David F. Mota
Summary: The Lambda-Cold Dark Matter model is currently the most accurate model for explaining cosmological observations, but there are still issues at galactic scales. Various models of dark matter, such as superfluid dark matter, Bose-Einstein Condensate (BEC) dark matter, and fuzzy dark matter, have been proposed to address these shortcomings. This study investigates these models using the constraint on gravitational wave propagation speed from the detection of the binary neutron star GW170817 by the LIGO-Virgo detector network. The findings suggest that the fuzzy dark matter model is the most feasible scenario to be tested in the near future, especially with detection frequencies < 10-9 Hz.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Theodoros Papanikolaou, Andreas Lymperis, Smaragda Lola, Emmanuel N. Saridakis
Summary: Primordial black holes (PBHs) can be formed through non-canonical inflation, and can provide observational evidence of the early Universe. Constraints on the non-canonical exponents are extracted by requiring significant PBH production. Asteroid-mass PBHs can explain the dark matter, and solar-mass PBHs within the LIGO-VIRGO detection band can be produced. The collapse of enhanced cosmological perturbations that form PBHs can also generate a detectable stochastic gravitational wave (GW) background.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Shreya Banerjee, Maria Petronikolou, Emmanuel N. Saridakis
Summary: We investigate the cosmological applications of gravitational scalar-tensor theories and analyze them in the context of the H0 tension. Two specific models are explored, showing negligible effects at high redshifts but an increasing deviation as time passes. At low redshifts, the Hubble parameter takes on higher values in a controlled manner. This behavior is attributed to the phantom nature of the effective dark-energy equation-of-state parameter, providing a possible solution to the H0 tension. Comparison with cosmic chronometer data demonstrates full agreement within 1σ confidence level.
Article
Astronomy & Astrophysics
Petros Asimakis, Spyros Basilakos, Andreas Lymperis, Maria Petronikolou, Emmanuel N. Saridakis
Summary: This study constructs new classes of modified theories that couple the matter sector with the Einstein tensor, specifically considering direct couplings to the energy-momentum tensor and its trace derivatives. The general field equations, without higher-order derivatives, are derived and applied in a cosmological framework, resulting in Friedmann equations with additional terms that give rise to an effective dark energy sector. The study shows successful description of the thermal history of the universe at the background level, with matter and dark energy epochs, and the dark energy equation-of-state parameter can approach -1 as time progresses. Comparison with cosmic chronometer data demonstrates a very good agreement. Detailed investigations of scalar and tensor perturbations validate the predicted behavior of the matter overdensity.
Article
Chemistry, Multidisciplinary
Mita Dutta, Shreya Banerjee, Mahitosh Mandal, Manish Bhattacharjee
Summary: A self-healable metallohydrogel of Mn(ii) has been successfully prepared using a low molecular weight gelator, Na2HL. It has been characterized by various techniques and encapsulated with drugs IND and GEM. The GEM-loaded metallogel showed enhanced delivery and cytotoxicity against breast cancer cells, while the MOG_IND exhibited improved anti-inflammatory response compared to the drug alone.
Article
Astronomy & Astrophysics
Wompherdeiki Khyllep, Jibitesh Dutta, Emmanuel N. Saridakis, Kuralay Yesmakhanova
Summary: Motivated by the success of f(Q) gravity in fitting observational data, we analyze the behavior of two studied f(Q) models, power-law and exponential, through dynamical system analysis. We find that both models have a matter-dominated saddle point followed by a stable dark-energy-dominated accelerated universe. The models fit observational data well and can be considered as promising alternatives to the ACDM concordance model.
Article
Physics, Particles & Fields
Sebastian Bahamonde, Konstantinos F. Dialektopoulos, Manuel Hohmann, Jackson Levi Said, Christian Pfeifer, Emmanuel N. Saridakis
Summary: This study focuses on the cosmological perturbation theory in f(T) gravity, which is a simple extension of the teleparallel equivalent of general relativity. The authors examine the possibility of a non-flat FLRW background solution and perform perturbations for different spatial geometries. They determine the behavior of the perturbative modes in this non-flat FLRW setting for arbitrary f(T) models and identify propagating modes.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Astronomy & Astrophysics
Lei-Hua Liu, Mian Zhu, Wentao Luo, Yi-Fu Cai, Yi Wang
Summary: We systematically investigate the microlensing effect of a charged spherically symmetric wormhole, where the light source is remote from the throat. The numerical result shows that the range of total magnification is from 105 to 10-2 depending on various metrics. Our theoretical investigation could shed new light on exploring the wormhole with the microlensing effect.
Article
Physics, Particles & Fields
Fotios K. Anagnostopoulos, Viktor Gakis, Emmanuel N. Saridakis, Spyros Basilakos
Summary: The f(Q) theories of modified gravity, based on non-metricity as the fundamental geometric quantity, have shown great effectiveness in describing the late-time Universe. By using Big Bang Nucleosynthesis (BBN) formalism and observations, constraints on various classes of f(Q) models are obtained. The deviations on the freeze-out temperature caused by f(Q) terms are calculated and constraints on the model parameters are imposed by applying the observational bound on |delta Tf/Tf|. It is found that f(Q) gravity can pass the BBN constraints, distinguishing itself from many other gravitational modifications that fail to do so.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Physics, Particles & Fields
Theodoros Papanikolaou, Charalampos Tzerefos, Spyros Basilakos, Emmanuel N. Saridakis
Summary: Research shows that the fluctuations of primordial black holes can be used as a novel tool to test general relativity and constrain possible modified gravity deviations in the framework of f(T) gravity. By investigating three viable mono-parametric models, we find that the deviations from general relativity in terms of the gravitational-wave source and propagation are negligible within the observationally allowed range of f(T) model parameters. Therefore, we conclude that realistic and viable f(T) theories can safely pass the primordial black hole constraints, providing additional support for them.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Astronomy & Astrophysics
Yu-Min Hu, Yaqi Zhao, Xin Ren, Bo Wang, Emmanuel N. Saridakis, Yi-Fu Cai
Summary: This study investigates the scalar perturbations and possible strong coupling issues of f(T) gravity using the effective field theory (EFT) approach. The generalized EFT framework of modified teleparallel gravity is revisited and applied to examine both linear and second-order perturbations in f(T) theory. The results suggest that there is no new scalar mode present in f(T) gravity, indicating a strong coupling problem. However, an estimation of the strong coupling scale based on the ratio of cubic to quadratic Lagrangians shows that the strong coupling problem can be avoided for certain modes.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Ali Dehghani, Behnam Pourhassan, Soodeh Zarepour, Emmanuel N. Saridakis
Summary: This study investigates the thermodynamic schemes of charged BTZ-like black holes in arbitrary dimensions. Two possible thermodynamic schemes are identified with different outcomes. In the traditional scheme, the charged black holes violate the reverse isoperimetric inequality and have a fundamental thermodynamic instability. In the second scheme, the black holes are thermodynamically stable and can explain the van der Waals critical phenomenon.
PHYSICS OF THE DARK UNIVERSE
(2023)
