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We investigate the saturation of particle acceleration in relativistic reconnection using two-dimensional particle-in-cell simulations at various magnetizations \sigma. We find that the particle energy spectrum produced in reconnection…

High Energy Astrophysical Phenomena · Physics 2018-03-14 Daniel Kagan , Ehud Nakar , Tsvi Piran

We study the $\Lambda(\alpha)$CDM models with $\Lambda(\alpha)$ being a function of the time-varying fine structure constant $\alpha$. We give a close look at the constraints on two specific $\Lambda(\alpha)$CDM models with one and two…

Cosmology and Nongalactic Astrophysics · Physics 2018-09-13 Jin-Jun Zhang , Lu Yin , Chao-Qiang Geng

A higher value of Hubble constant has been obtained from measurements with nearby Type Ia supernovae, than that obtained at much higher redshift. With the peculiar motions of their hosts, we find that the matter content at such low redshift…

Cosmology and Nongalactic Astrophysics · Physics 2013-07-25 Shuang-Nan Zhang , Yin-Zhe Ma

We revisit the Cosmic Microwave Background (CMB) constraints on the spatial curvature of the Universe, assessing how they change when the curvature parameter and the primordial inflationary scalar spectrum are treated consistently within…

Cosmology and Nongalactic Astrophysics · Physics 2025-10-01 Enrico Specogna , Tatevik Vardanyan , William Giarè , Eleonora Di Valentino

We attempt to find new symmetries in the space-time structure, leading to a modified gravitation at large length scales, which provides the foundations of a quantum gravity at very low energies. This search begins by considering a unified…

General Relativity and Quantum Cosmology · Physics 2007-09-13 Claudio Nassif

We study multidimensional gravitational models with scalar curvature nonlinearity of the type 1/R and with form-fields (fluxes) as a matter source. It is assumed that the higher dimensional space-time undergoes Freund-Rubin-like spontaneous…

High Energy Physics - Theory · Physics 2008-11-26 Tamerlan Saidov , Alexander Zhuk

We investigate lattice Weinberg - Salam model without fermions numerically for the realistic choice of coupling constants correspondent to the value of the Weinberg angle $\theta_W \sim 30^o$, and bare fine structure constant around $\alpha…

High Energy Physics - Lattice · Physics 2010-11-19 M. A. Zubkov

We use measurements from the Planck satellite mission and galaxy redshift surveys over the last decade to test three of the basic assumptions of the standard model of cosmology, $\Lambda$CDM: the spatial curvature of the universe, the…

Cosmology and Nongalactic Astrophysics · Physics 2016-01-20 Shadab Alam , Shirley Ho , Alessandra Silvestri

The physics of particle acceleration in turbulent plasmas is a topic of broad interest, which is making rapid progress thanks to dedicated, large-scale numerical experiments. The first part of this paper presents an effective theory of…

Plasma Physics · Physics 2025-07-08 M. Lemoine

Models of relativistic particle with Lagrangian ${\cal L}(k_1)$, depending on the curvature of the worldline $k_1$, are considered. By making use of the Frenet basis, the equations of motion are reformulated in terms of the principal…

High Energy Physics - Theory · Physics 2009-10-28 V. V. Nesterenko , A. Feoli , G. Scarpetta

We consider classically scale-invariant theories with non-minimally coupled scalar fields, where the Planck mass and the hierarchy of physical scales are dynamically generated. The classical theories possess a fixed point, where scale…

High Energy Physics - Phenomenology · Physics 2017-05-03 K. Kannike , M. Raidal , C. Spethmann , H. Veermäe

Models of structure formation with a cosmological constant $\Lambda$ provide a good fit to the observed power spectrum of galaxy clustering. However, they suffer from several problems. Theoretically, it is difficult to understand why the…

Astrophysics · Physics 2010-11-30 K. Coble , S. Dodelson , J. Frieman

In the `condensed phase' of effective quantum field theories one expects deviations from exact Lorentz invariance at ultralow momenta | k| < delta where the shell 'delta' should only vanish in the strict local limit of the theory when the…

High Energy Physics - Phenomenology · Physics 2007-05-23 M. Consoli

Matter and quasi-matter bounce scenarios are studied for an F(R) gravity model with holonomy corrections and a Lagrange multiplier, with a scale factor $a(t) = \left(a_0t^2 + 1 \right)^n$, where the Hubble parameter squared has a linear and…

General Relativity and Quantum Cosmology · Physics 2020-01-29 Emilio Elizalde , S. D. Odintsov , Tanmoy Paul

This paper explores models of the FLRW universe that incorporate a time-varying cosmological term $\Lambda(t)$. Specifically, we assume a power-law form for the cosmological term as a function of the scale factor: $\Lambda(t)=\Lambda_{0}…

Cosmology and Nongalactic Astrophysics · Physics 2024-05-14 M. Koussour , N. Myrzakulov , J. Rayimbaev

A numerical evidence for the universality of the bound-zone peculiar velocity profile in a LambdaCDM universe is presented. Analyzing the dark matter halo catalogs from the Millennium-II simulation, we determine the average peculiar…

Cosmology and Nongalactic Astrophysics · Physics 2016-12-15 Jounghun Lee

We derive the radiation characteristics of an accelerated, charged particle in a model due to Caianiello in which the proper acceleration of a particle of mass $m$ has the upper limit $\mathcal{A}_m=2mc^3/\hbar$. We find two power laws, one…

General Relativity and Quantum Cosmology · Physics 2015-09-01 Giorgio Papini

The fine structure constant $\alpha$ has a particular status in physics. Its precise determination is required to test the quantum electrodynamics (QED) theory. The constant $\alpha$ is also a keystone for the determination of other…

We investigate the renormalization group flow of a gravity--matter system in which a scalar field is minimally coupled to Einstein gravity and its kinetic term is given by a scale-dependent form factor $f_\Lambda(-\Box)$. Employing the…

High Energy Physics - Theory · Physics 2026-05-13 Alfio M. Bonanno , Diego Buccio , Emiliano M. Glaviano , Frank Saueressig

We study electroweak interactions in the multiscale theory with $q$-derivatives, a framework where spacetime has the typical features of a multifractal. In the simplest case with only one characteristic time, length and energy scale $t_*$,…

High Energy Physics - Theory · Physics 2016-01-12 Gianluca Calcagni , Giuseppe Nardelli , David Rodríguez-Fernández