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The $S_8$ tension between low-redshift galaxy surveys and the primary CMB signals a possible breakdown of the $\Lambda$CDM model. Recently differing results have been obtained using low-redshift galaxy surveys and the higher redshifts…

Cosmology and Nongalactic Astrophysics · Physics 2024-03-19 Meng-Xiang Lin , Bhuvnesh Jain , Marco Raveri , Eric J. Baxter , Chihway Chang , Marco Gatti , Sujeong Lee , Jessica Muir

We study two types of entropic-force models in a homogeneous, isotropic, spatially flat, matter-dominated universe. The first type is a `$\Lambda(t)$ type' similar to $\Lambda(t)$CDM (varying-lambda cold dark matter) models in which both…

Cosmology and Nongalactic Astrophysics · Physics 2014-06-11 Nobuyoshi Komatsu , Shigeo Kimura

Epidemic models with inhomogeneous populations have been used to study major outbreaks and recently Britton and Lindenstrand \cite{BL} described the case when latency and infectivity have independent gamma distributions. They found that…

Populations and Evolution · Quantitative Biology 2010-12-17 C. T. J. Dodson

We present constraints on the cosmic growth history with recent cosmological data, allowing for deviations from Lambda CDM as might arise if cosmic acceleration is due to modifications to GR or inhomogeneous dark energy. We combine measures…

Cosmology and Nongalactic Astrophysics · Physics 2010-05-12 Rachel Bean , Matipon Tangmatitham

We discuss the possibility of deriving an H-theorem for the nonlinear discrete time evolution known as Ulam's redistribution of energy problem. In this model particles are paired at random and then their total energy is redistributed…

Statistical Mechanics · Physics 2013-06-06 S. M. Apenko

We describe a combined halo model to constrain the distribution of neutral hydrogen (HI) in the post-reionization universe. We combine constraints from the various probes of HI at different redshifts: the low-redshift 21-cm emission line…

Cosmology and Nongalactic Astrophysics · Physics 2017-08-23 Hamsa Padmanabhan , Alexandre Refregier

Practically, training diffusion models typically requires explicit time conditioning to guide the network through the denoising sampling process. Especially in deterministic methods like DDIM, the absence of time conditioning leads to…

Machine Learning · Computer Science 2026-04-29 Liuzhuozheng Li , Zhiyuan Zhan , Shuhong Liu , Dengyang Jiang , Zanyi Wang , Guang Dai , Jingdong Wang , Mengmeng Wang

In this work, we have proposed a general dark energy density parametrization to study the evolution of the universe. We have also constrained the model parameters using the combination of Type Ia supernova (SNIa), baryonic acoustic…

General Relativity and Quantum Cosmology · Physics 2018-07-25 Abdulla Al Mamon

MaxEnt inference algorithm and information theory are relevant for the time evolution of macroscopic systems considered as problem of incomplete information. Two different MaxEnt approaches are introduced in this work, both applied to…

Statistical Mechanics · Physics 2012-02-21 Domagoj Kuic , Pasko Zupanovic , Davor Juretic

Recent analyses of the Master Type Ia supernova (SN Ia) sample have revealed a mild redshift dependence in the inferred local Hubble parameter, often expressed as tilde{H}_0(z) = H_0 (1+z)^{-\alpha}, where \alpha quantifies possible…

General Physics · Physics 2025-11-12 Seokcheon Lee

Observations of the neutral Hydrogen (\HI ) 21-cm signal hold the potential of allowing us to map out the cosmological large scale structures (LSS) across the entire post-reionization era ($z \leq 6$). Several experiments are planned to map…

Cosmology and Nongalactic Astrophysics · Physics 2016-05-11 Debanjan Sarkar , Somnath Bharadwaj , Anathpindika S.

We investigate the decay of spatial correlations of $\mathcal{PT}$-symmetric non-Hermitian one-dimensional models that host higher-order exceptional points. Beyond a certain correlation length, they develop anomalous power-law behavior that…

Mesoscale and Nanoscale Physics · Physics 2023-08-16 Doru Sticlet , Cătălin Paşcu Moca , Balázs Dóra

We derive an analytic model for the redshift evolution of linear-bias, allowing for interactions and merging of the mass-tracers, by solving a second order differential equation based on linear perturbation theory and the Friedmann-Lemaitre…

Astrophysics · Physics 2009-11-13 S. Basilakos , M. Plionis , C. Ragone-Figueroa

The evolution of the Hubble parameter $H(z)$ with redshift $z$ is estimated from the Pantheon+ data of Type Ia supernovae, for the $\Lambda$CDM model and the three special cases of the eternal coasting (EC) cosmological model with three…

Cosmology and Nongalactic Astrophysics · Physics 2024-12-23 Ardra Edathandel Sasi , Moncy Vilavinal John

We consider model order reduction of parameterized Hamiltonian systems describing nondissipative phenomena, like wave-type and transport dominated problems. The development of reduced basis methods for such models is challenged by two main…

Numerical Analysis · Mathematics 2021-05-27 Cecilia Pagliantini

The present work employs the Linder parametrization of a constant growth index \cite{linder/index} to investigate the evolution of growth rate of clustering and the dissipation of configurational entropy in some of the most widely studied…

General Relativity and Quantum Cosmology · Physics 2021-09-03 Snehasish Bhattacharjee

By depleting the ionizing photon budget available to expand cosmic HII regions, recombining systems (or Lyman limit systems) can have a large impact during (and following) cosmic reionization. Unfortunately, directly resolving such…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-18 Emanuele Sobacchi , Andrei Mesinger

In this paper we study the reductions of evolutionary PDEs on the manifold of the stationary points of time-dependent symmetries. In particular we describe how the finite dimensional Hamiltonian structure of the reduced system is obtained…

solv-int · Physics 2007-05-23 Monica Ugaglia

High-precision cosmological observations have revealed persistent tensions within the standard $\Lambda$CDM paradigm, most notably the discrepancy in the Hubble constant and the lower than predicted amplitude of late-time matter clustering…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-28 Biswajit Pandey

The concept of entropy in nonequilibrium macroscopic systems is investigated in the light of an extended equation of motion for the density matrix obtained in a previous study. It is found that a time-dependent information entropy can be…

Statistical Mechanics · Physics 2009-11-10 W. T. Grandy