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Scalar-tensor theories of gravity provide a consistent framework to accommodate an ultra-light quintessence scalar field. While the equivalence principle is respected by construction, deviations from General Relativity and standard…

Astrophysics · Physics 2008-11-26 R. Catena , N. Fornengo , A. Masiero , M. Pietroni , F. Rosati

The relic abundance of asymmetric Dark Matter particles in the scalar--tensor model is analysized in this article. We extend the numeric and analytic calculation of the relic density of the asymmetric Dark Matter in the standard…

High Energy Physics - Phenomenology · Physics 2016-03-16 Shun-zhi Wang , Hoernisa Iminniyaz , Mamatrishat Mamat

In Scalar-Tensor theories of gravity, the expansion rate of the universe in the past may differ considerably from the standard one. After imposing the constraints coming from nucleosynthesis, CMB, type Ia supernovae, and solar system tests…

Astrophysics · Physics 2007-05-23 R. Catena , N. Fornengo , A. Masiero , M. Pietroni , F. Rosati

We investigate the thermal relic density of the cold dark matter in the context of the brane world cosmology. Since the expansion law in a high energy regime is modified from the one in the standard cosmology, if the dark matter decouples…

High Energy Physics - Phenomenology · Physics 2016-09-06 Nobuchika Okada , Osamu Seto

Relic density calculations are often used to constrain particle physics models, and in particular supersymmetry. We will show that the presence of additional energy or entropy before the Big-Bang nucleosynthesis can however completely…

High Energy Physics - Phenomenology · Physics 2014-11-20 A. Arbey , F. Mahmoudi

We calculate the relic density ($\Omega_{\chi^0_1} h^2$) of neutralino dark matter in supergravity models with radiative electroweak symmetry breaking, for values of the Higgs sector parameter $\tan\beta \equiv v_2/v_1$ between the two…

High Energy Physics - Phenomenology · Physics 2016-09-06 V. Barger , Chung Kao

We investigate the relic density n_\chi of non-relativistic long-lived or stable particles \chi in non-standard cosmological scenarios. We calculate the relic abundance starting from arbitrary initial temperatures of the radiation-dominated…

High Energy Physics - Phenomenology · Physics 2008-11-26 Manuel Drees , Hoernisa Iminniyaz , Mitsuru Kakizaki

If the early universe is dominated by an energy density which evolves other than radiation-like the normal Hubble-temperature relation $H\propto T^2$ is broken and dark matter relic density calculations in this era can be significantly…

High Energy Physics - Phenomenology · Physics 2025-11-06 Carlos Maldonado , James Unwin

The relic density of symmetric and asymmetric dark matter in a Gauss-Bonnet (GB) modified Randall-Sundrum (RS) type II braneworld cosmology is investigated. The existing study of symmetric dark matter in a GB braneworld (Okada and Okada,…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-19 Michael T. Meehan , Ian B. Whittingham

Scalar dark matter can interact with Standard Model (SM) particles, altering the fundamental constants of Nature in the process. Changes in the fundamental constants during and prior to Big Bang nucleosynthesis (BBN) produce changes in the…

Cosmology and Nongalactic Astrophysics · Physics 2015-04-14 Y. V. Stadnik , V. V. Flambaum

Models of scalar field dark matter where the scalar is a dilaton have a special behaviour, since non-trivial couplings, $d$, to matter result in a contribution to the potential for the field which is proportional to the trace of the…

High Energy Physics - Phenomenology · Physics 2024-06-11 Ahmad Alachkar , Malcolm Fairbairn , David J. E. Marsh

The decoupling of a cold relic, during a decaying-particle-dominated cosmological evolution is analyzed, the relic density is calculated both numerically and semi-analytically and the results are compared with each other. Using plausible…

High Energy Physics - Phenomenology · Physics 2011-05-23 C. Pallis

We investigate scenarios in which a charged, long-lived scalar particle decouples from the primordial plasma in the Early Universe. We compute the number density at time of freeze-out considering both the cases of abelian and non-abelian…

High Energy Physics - Phenomenology · Physics 2008-11-26 Carola F. Berger , Laura Covi , Sabine Kraml , Federica Palorini

We calculate the relic density of the lightest neutralino in a supersymmetric seesaw type-II (``triplet seesaw'') model with minimal supergravity boundary conditions at the GUT scale. The presence of a triplet below the GUT scale, required…

High Energy Physics - Phenomenology · Physics 2009-11-10 J. N. Esteves , M. Hirsch , S. Kaneko , W. Porod , J. C. Romao

We investigate the thermal relic density of a cold dark matter in the brane world cosmology. Since the expansion law in a high energy regime is modified from the one in the standard cosmology, if the dark matter decouples in such a high…

High Energy Physics - Phenomenology · Physics 2007-05-23 Nobuchika Okada , Osamu Seto

We propose a new unified model that describes~dark energy and dark matter in the context of $f(R,\phi )$ gravity using a massive scalar field in five dimensions. The scalar field is considered in the bulk that surrounds the 3-brane in…

General Relativity and Quantum Cosmology · Physics 2021-05-13 M. Bousder , Z. Sakhi , M. Bennai

Dark Matter relic density generation through \textit{freeze-in} mechanism where dark matter particles interact feebly with visible sector particles, is an alternative approach to well-studied and most popular \textit{freeze-out} paradigm.…

High Energy Physics - Phenomenology · Physics 2026-01-27 Joydeep Roy

Scalar fields with $SU(2)_L$ quantum numbers provide several viable Dark Matter candidates around the TeV scale. Thanks to scalar quartic interactions, the observed relic density can be obtained for a large range of masses, which we…

High Energy Physics - Phenomenology · Physics 2009-06-01 Fu-Sin Ling

The thermal relic density of the neutralino dark matter in the brane world cosmology is studied. Since the expansion law at a high energy regime in the brane world cosmology is modified from the one in the standard cosmology, the resultant…

High Energy Physics - Phenomenology · Physics 2009-11-10 Takeshi Nihei , Nobuchika Okada , Osamu Seto

We calculate the relic density of very heavy, stable scalar neutrinos in the minimal supersymmetric standard model. We include all two-body final states, as well as the effects of co-annihilation with scalar electrons. We find that the…

High Energy Physics - Phenomenology · Physics 2008-11-26 Toby Falk , Keith A. Olive , Mark Srednicki
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