Article
Astronomy & Astrophysics
Pavan Kumar Aluri, Sanjeet Kumar Patel
Summary: This paper examines the first peculiarities observed in cosmic microwave background (CMB) data, namely the breakdown of statistical isotropy in terms of axiality and planarity of low multipoles. By analyzing the latest CMB data from ESA's Planck mission, it is found that there are a significant number of intrinsically anisotropic modes, but not all of them are intrinsically planar. The alignment between the quadrupole and octopole is still observed, while higher multipoles aligned with the quadrupole are insignificant. Interestingly, the collective alignment axis of the first sixty multipoles is closer to the axis of the dipole, quadrupole, octopole, and other modes aligned with l = 2.
Article
Astronomy & Astrophysics
A. Hernandez-Almada, Genly Leon, Juan Magana, Miguel A. Garcia-Aspeitia, V Motta, Emmanuel N. Saridakis, Kuralay Yesmakhanova
Summary: In this study, we investigate Kaniadakis-holographic dark energy by comparing it with observational data. By conducting a Markov Chain Monte Carlo analysis using cosmic chronometers, supernovae type Ia, and Baryon Acoustic Oscillations data, we find that the Kaniadakis parameter is constrained around zero, which is consistent with the standard Bekenstein-Hawking entropy. Additionally, the present matter density parameter Omega((0))(m) is slightly smaller in the Kaniadakis scenario compared to the Lambda CDM model. Furthermore, we reconstruct the evolution of the Hubble, deceleration, and jerk parameters and extract the redshift of the deceleration-acceleration transition.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Vivian Sabla, Robert R. Caldwell
Summary: Early dark energy, proposed as a solution to the Hubble tension, faces a challenge regarding its emergence just before recombination. The model of assisted quintessence attempts to explain this connection through scaling fields, but ultimately leads to the failure of the scenario. This failure sheds light on the ability of new physics to resolve the Hubble tension.
Article
Astronomy & Astrophysics
F. S. Mirtalebian, Kourosh Nozari, Tahereh Azizi
Summary: This paper presents reheating constraints on an inflationary universe induced by perfect fluid models, outlining the procedure to calculate inflationary observables and reheating. By restricting the equation-of-state parameter in the reheating stage, more stringent constraints can be derived for the model's parameter space, corresponding to viable values of the scalar spectral index ns and tensor-to-scalar ratio r released by Planck2018 observational data.
ASTROPHYSICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
Sergei D. Odintsov, Simone D'Onofrio, Tanmoy Paul
Summary: The increasing interest in different entropy functions in cosmology raises the question of whether there is a generalized entropy that can unify all known entropies. A four-parameter generalized entropy has recently been formulated, which reduces to different known entropies in specific parameter limits. In this paper, the authors investigate the early phase of the universe's evolution, particularly from inflation to reheating, using the concept of entropic energy density. The results show that entropic energy can drive an early inflationary phase and the theoretical expectations are consistent with recent observational data.
PHYSICS OF THE DARK UNIVERSE
(2023)
Article
Astronomy & Astrophysics
M. Sabiee, M. Malekjani, D. Mohammad Zadeh Jassur
Summary: In this paper, the power-law f(T) model is studied using various cosmographic methods. The study shows that the PADE (3,2) polynomial is the best approximation for reconstructing the distance modulus in the cosmographic method. The power-law f(T) model is found to be consistent with observational data, and the combination of the Hubble diagram of SNIa and the BAO observation improves the consistency between the model-independent cosmographic method and the power-law f(T) model.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Physics, Particles & Fields
F. B. M. dos Santos, J. E. Gonzalez, R. Silva
Summary: We establish new constraints on f(T) gravity models using various cosmological data sets. We find significant improvements on the constraints of the b-parameter when comparing the results to the statistical analysis. In addition, we make predictions for future constraints on the deviation of f(T) models from the Lambda CDM scenario.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Astronomy & Astrophysics
Ester Piedipalumbo, Stefano Vignolo, Pasquale Feola, Salvatore Capozziello
Summary: In this study, we investigate the non-flat interacting quintessence cosmology within the framework of scalar-tensor gravity, where a scalar field interacts with dark matter. By employing the Noether Symmetry Approach, we obtain general exact solutions for cosmological equations and determine the scalar-field self-interaction potentials. The obtained solutions are capable of reproducing the accelerated expansion of the Universe and are consistent with various observational datasets, including the SNeIa Pantheon data, gamma ray bursts Hubble diagram, and direct measurements of the Hubble parameter.
PHYSICS OF THE DARK UNIVERSE
(2023)
Article
Astronomy & Astrophysics
U. Y. Divya Prasanthi, Y. Aditya
Summary: This paper discusses the cosmic evolution of the anisotropic and spatially homogeneous Kantowski-Sachs universe with Renyi holographic dark energy in the background of general relativity. The study includes calculations of cosmological aspects of dynamical parameters, such as the dark energy equation of state parameter, and explores the stability of the model, which is found to be stable at initial epoch but unstable at present and late times. The analysis also indicates that the model comprises quintessence, phantom dark energy regions, and the Lambda CDM limit.
PHYSICS OF THE DARK UNIVERSE
(2021)
Article
Astronomy & Astrophysics
Zihao Li, Bin Zhang, Nan Liang
Summary: We calibrate gamma-ray burst (GRB) using a cosmology-independent method based on observational Hubble data (OHD) and the cosmic chronometer method. By reconstructing OHD using Gaussian process, we calibrate the Amati relation (E-p-E-iso) and construct a GRB Hubble diagram with the A118 data set. We also constrain dark energy models in a flat space using the Markov chain Monte Carlo numerical method. The results show no significant evidence supporting deviations from the standard Lambda cold dark matter model.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Multidisciplinary Sciences
Amrita Sarkar, Surajit Chattopadhyay, Ertan Gudekli
Summary: A scheme utilizing the holographic Ricci dark energy for the generalized Chaplygin gas equation of state was presented. Regression analysis and chi-square tests were conducted to establish a second order polynomial regression for the relation between the Hubble Parameter and redshift. Parameters were also determined to predict the Equation of State (EoS) parameter.
Article
Biochemical Research Methods
Qi Jiang, Shuo Zhang, Lin Wan
Summary: This study introduces a novel nonlinear model and dynamic inference framework based on graphs, which can reconstruct cell state transitions and unveil nonlinear cell-cell interactions from single-cell RNA data, showing promising applications in understanding cellular dynamics.
PLOS COMPUTATIONAL BIOLOGY
(2022)
Article
Astronomy & Astrophysics
Samuel Goldstein, Shivam Pandey, Anze Slosar, Jonathan Blazek, Bhuvnesh Jain
Summary: In this study, we analyzed the clustering of galaxies using the CosmoDC2 simulation data. We provided subpercent measurements of galaxy autocorrelation and galaxy-dark matter cross correlations in Fourier space and configuration space. We used a hybrid-PT model to model nonlinear galaxy bias with 0.5% precision and found that the linear bias parameter was measured with 0.01% precision. Our results showed consistency between galaxy samples defined using different magnitude bands and moderate to significant tension between Fourier space and configuration space approaches.
Article
Computer Science, Information Systems
Danda B. Rawat, Ronald Doku, Moses Garuba
Summary: Knowledge is derived from having access to information, which has become a crucial issue in today's information age. The use of big data in cybersecurity to protect assets, as well as its high value as a target, highlights the importance of understanding the inner workings of systems producing data in the current technological landscape.
IEEE TRANSACTIONS ON SERVICES COMPUTING
(2021)
Article
Astronomy & Astrophysics
Aurlien Barrau, Cyril Renevey, Killian Martineau
Summary: This article discusses the ability of future cosmological surveys to constrain string theory and the potential impact, exploring possible conclusions through analysis of future observatories.
ASTROPHYSICAL JOURNAL
(2021)
Article
Physics, Particles & Fields
Claudio Coriano, Luigi Delle Rose, Kostas Skenderis
Summary: Theories with generalised conformal structure exhibit similar properties to conformal field theories in lower dimensions, where the standard normalization constant is replaced by a function of the effective coupling constant g constructed from dimensionful parameters and the separation of operators. These theories play a role in holographic dualities involving non-conformal branes, and the phi(6) coupling, while irrelevant in the context of generalised conformal structure, has effects in the UV regime.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Physics, Particles & Fields
Stefania De Curtis, Luigi Delle Rose, Andrea Guiggiani, Angel Gil Muyor, Giuliano Panico
Summary: First-order phase transitions have significant implications in the early universe, including the generation of gravitational waves and baryon asymmetry. This study presents the full solution of the linearized Boltzmann equation for the top quark species coupled to the Higgs field during a first-order electroweak phase transition, revealing notable differences from traditional fluid approximation methods.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Physics, Particles & Fields
Luigi Delle Rose, Benedict von Harling, Alex Pomarol
Summary: We present a method to simplify the calculation of finite contributions from heavy particles to EFT Wilson coefficients using on-shell methods. We apply this technique to the one-loop calculation of g-2 and H gamma gamma and demonstrate how finite contributions can be obtained from the product of tree-level amplitudes. By exploiting the parity symmetry of these amplitudes, we discover that in certain cases the total contribution adds up to zero, consistent with previous findings. Our method allows for the search of new natural zeros and enables the straightforward determination of non-zero contributions.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Physics, Multidisciplinary
Jose Manuel Penin, Kostas Skenderis, Benjamin Withers
Summary: In this study, we investigate the properties of strongly coupled mass-deformed CFT on a fixed de Sitter spacetime using holography. We elucidate the causal structure of the four-dimensional spacetime dual to the de Sitter invariant vacuum state and compute the correlation functions of the deformed-CFT stress tensor and scalar operator at each order of the mass deformation.
Article
Astronomy & Astrophysics
Matthew P. G. Robbins, Niayesh Afshordi, Alan O. Jamison, Robert B. Mann
Summary: This article presents an interesting proposal for detecting gravitational waves using Bose-Einstein condensates. By modulating the speed of sound in the condensate, the sensitivity to gravitational waves can be enhanced. The study finds that such a detector has the potential to detect gravitational waves across a wide range of frequencies.
CLASSICAL AND QUANTUM GRAVITY
(2022)
Article
Astronomy & Astrophysics
Nico Benincasa, Luigi Delle Rose, Kristjan Kannike, Luca Marzola
Summary: The inert doublet model is an extension of the Standard Model that has implications for understanding dark matter and cosmic evolution through the study of cosmic phase transitions and gravitational wave signals.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Physics, Particles & Fields
Adam Bzowski, Paul McFadden, Kostas Skenderis
Summary: In this paper, we present a comprehensive discussion on the tree-level holographic 4-point functions of scalar operators in momentum space. We demonstrate that each Witten diagram satisfies the conformal Ward identities independently, making it a valid conformal correlator. Furthermore, we provide explicit formulas for evaluating Witten diagrams when certain conditions are met. Renormalization is necessary for these correlators and it leads to new conformal anomalies and beta functions. We also explore the idea of weight-shifting operators to link correlators of operators with different dimensions.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Physics, Particles & Fields
Raffaele Marotta, Kostas Skenderis, Mritunjay Verma
Summary: We examined the 3-point CFT correlators involving non-conserved spinning operators in momentum space. A general expression for the conformal Ward identities defining the 3-point functions involving two generic spin s non-conserved operators and a spin 1 conserved current was derived. Explicit expressions for the 3-point function were provided when the two non-conserved operators have spins 1 and 2 and generic conformal dimensions. The divergences appearing in these 3-point functions when the conformal dimensions of the two non-conserved operators coincide were also systematically analyzed.
JOURNAL OF HIGH ENERGY PHYSICS
(2023)
Article
Astronomy & Astrophysics
Alice Y. Chen, Niayesh Afshordi
Summary: Halo models of large scale structure are important for understanding the clustering of matter in the Universe. This paper addresses the issue of defining halo profiles beyond their virial radii and provides a systematic definition that can be matched to simulation results. The compensating halo profiles are crucial for the calculation of cosmological correlation functions in an amended halo model.
Article
Astronomy & Astrophysics
Enrico Parisini, Kostas Skenderis, Benjamin Withers
Summary: We generalize the embedding space formalism to conformal field theories (CFTs) on nontrivial states and curved backgrounds using the ambient metric of Fefferman and Graham. The construction of CFT n-point functions in these settings is based on appropriate geometric invariants of the ambient space. Exact agreement with holographic computations and expectations from thermal operator product expansions (OPEs) is found for two-point functions of thermal CFT, and the method is also applied to CFTs on squashed spheres with no prior results available, demonstrating its utility.
Article
Astronomy & Astrophysics
Maximo Banados, Ernesto Bianchi, Ivan Munoz, Kostas Skenderis
Summary: We have developed a systematic procedure for renormalizing quantum field theories in anti-de Sitter spacetime. UV infinities are regulated using a geodesic point-splitting method, while IR infinities are regulated by cutting off the radial direction. We define the renormalized theory by introducing Z factors, boundary counterterm action, and renormalization conditions.
Article
Astronomy & Astrophysics
Niayesh Afshordi, Joao Magueijo
Summary: In this study, the researchers use the quantum unimodular theory of gravity to investigate the relationship between the cosmological constant and the energy scale for the emergence of cosmological classicality. The findings suggest that a perennially quantum Universe would occur if the cosmological constant is zero. The study also establishes a lower bound on the uncertainty of the unimodular clock or the cosmic time for the emergence of classicality based on the smallness of the cosmological constant. Classicality arises at around 7 x 1011 GeV for the observed value of the cosmological constant, highlighting the importance of understanding the classicality and quantum nature of the Universe.
Article
Astronomy & Astrophysics
Aaron Poole, Kostas Skenderis, Marika Taylor
Summary: In this paper, we discuss the definition of conserved quantities in asymptotically locally de Sitter spacetimes. We introduce the analog of holographic charges at future and past infinity and at other Cauchy surfaces, and explain the characteristics and changes of these charges.
Article
Astronomy & Astrophysics
Luis Felipe Longo Micchi, Niayesh Afshordi, Cecilia Chirenti
Summary: The first direct observations of gravitational waves by the LIGO collaboration have led to different tests of general relativity. One of these tests involves searching for extra pulses following the gravitational waveform. A new study provides estimates for the detectability of the first echo, suggesting that it may be detected by LIGO in the next few years.
