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We develop optimised estimators of two sorts of power spectra for fields defined on the sky, in the presence of partial sky coverage. The first is the cross-power spectrum of two fields on the sky; the second is the skew spectrum of three…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 Dipak Munshi , Patrick Valageas , Asantha Cooray , Alan Heavens

We provide a systematic and updated discussion of a research line carried out by our group over the last few years, in which gravity is modified at cosmological distances by the introduction of nonlocal terms, assumed to emerge at an…

Cosmology and Nongalactic Astrophysics · Physics 2020-04-15 Enis Belgacem , Yves Dirian , Andreas Finke , Stefano Foffa , Michele Maggiore

Modified gravity (MG) theories aim to reproduce the observed acceleration of the Universe by reducing the dark sector while simultaneously recovering General Relativity (GR) within dense environments. Void studies appear to be a suitable…

Cosmology and Nongalactic Astrophysics · Physics 2019-11-27 E L D Perico , R Voivodic , M Lima , D F Mota

In this study, we investigate gravitational lensing within modified gravity frameworks, focusing on the Hu-Sawicki $f(R)$ and normal branch Dvali-Gabadadze-Porrati (nDGP) models, and we compare these results with those obtained from general…

General Relativity and Quantum Cosmology · Physics 2025-01-03 Ali Tizfahm , Saeed Fakhry , Javad T. Firouzjaee , Antonino Del Popolo

We study perturbation theory for large-scale structure in the most general scalar-tensor theories propagating a single scalar degree of freedom, which include Horndeski theories and beyond. We model the parameter space using the effective…

Cosmology and Nongalactic Astrophysics · Physics 2020-06-09 Marco Crisostomi , Matthew Lewandowski , Filippo Vernizzi

This paper presents an improved implicit sampling method for hierarchical Bayesian inverse problems. A widely used approach for sampling posterior distribution is based on Markov chain Monte Carlo (MCMC). However, the samples generated by…

Numerical Analysis · Mathematics 2018-11-27 Xiaoyan Song , Lijian Jiang , Guanghui Zheng

In this paper we introduce a new public Einstein-Boltzmann solver, \texttt{MGCLASS II}, built as a modification to the publicly available \texttt{CLASS} code, that allows to obtain cosmological observables for Modified Gravity theories. It…

Cosmology and Nongalactic Astrophysics · Physics 2022-06-28 Ziad Sakr , Matteo Martinelli

This work is the extension of author`s research, where the modified theory of induced gravity (MTIG) is proposed. The theory describes two systems (stages): Einstein (ES) and "restructuring" (RS). We consider equations with quadratic…

General Physics · Physics 2019-11-22 Farkhat Zaripov

The screened modified gravity (SMG) is a unified theoretical framework, which describes the scalar-tensor gravity with screening mechanism. Based on the gravitational-wave (GW) waveform derived in our previous work \citep{liu2018waveforms},…

General Relativity and Quantum Cosmology · Physics 2020-02-28 Rui Niu , Xing Zhang , Tan Liu , Jiming Yu , Bo Wang , Wen Zhao

Bregman divergences play a central role in the design and analysis of a range of machine learning algorithms. This paper explores the use of Bregman divergences to establish reductions between such algorithms and their analyses. We present…

Machine Learning · Computer Science 2016-07-04 Richard Nock , Aditya Krishna Menon , Cheng Soon Ong

[abridged] Chern-Simons (CS) modified gravity is a 4D effective theory that descends both from string theory and loop quantum gravity, and that corrects the Einstein-Hilbert action by adding the product of a scalar field and the…

General Relativity and Quantum Cosmology · Physics 2009-11-06 Carlos F. Sopuerta , Nicolas Yunes

Observational cosmology has become an important laboratory for testing General Relativity, with searches for modified gravity forming a significant portion of the science case for existing and future surveys. In this paper, we illustrate…

Cosmology and Nongalactic Astrophysics · Physics 2019-10-23 Zhen Pan , Matthew C. Johnson

Galaxy bispectrum is a promising probe of inflationary physics in the early universe as a measure of primordial non-Gaussianity (PNG), whereas its signal-to-noise ratio is significantly affected by the mode coupling due to non-linear…

Cosmology and Nongalactic Astrophysics · Physics 2021-01-13 Masato Shirasaki , Naonori S. Sugiyama , Ryuichi Takahashi , Francisco-Shu Kitaura

We study structure formation in a phenomenological model of modified gravity which interpolates between LambdaCDM and phenomenological DGP-gravity. Generalisation of spherical collapse by using the Birkhoff-theorem along with the modified…

Astrophysics · Physics 2013-03-07 Bjoern Malte Schaefer , Kazuya Koyama

In the appropriate limit, a type IIB string theory setup involving D3 branes, wrapped D5 branes, and fluxes on a conifold generally leads to a supergravity background involving a warped version of the conifold with fluxes. We study the…

High Energy Physics - Theory · Physics 2018-06-06 Jake Elituv

General Relativity (GR) remains the cornerstone of gravitational physics, providing remarkable success in describing a wide range of astrophysical and cosmological phenomena. However, several challenges underscore the urgent need to explore…

General Relativity and Quantum Cosmology · Physics 2025-02-12 Susobhan Mandal , S. Shankaranarayanan

We put forward the idea that in addition to diffeomorphism invariance of general relativity (GR) the gravitational interaction is invariant under arbitrary scale-deformations of the metric field. In addition, we assume that the scaling…

General Relativity and Quantum Cosmology · Physics 2022-05-19 Meir Shimon

Primordial non-Gaussianities from multi-field inflation are a leading target for cosmological observations, because of the possible large correlations generated between long and short distances. These signatures are captured by the local…

Cosmology and Nongalactic Astrophysics · Physics 2023-05-31 Dong-Gang Wang , Guilherme L. Pimentel , Ana Achúcarro

We investigate static cylindrical solutions within an extended theory of modified gravity. By incorporating various coupling functions through a straightforward boost symmetry approach, we establish the equations of motion in a…

General Relativity and Quantum Cosmology · Physics 2024-07-31 Davood Momeni , Phongpichit Channuie , Mudhahir Al-Ajmi