arXiv subjects

A. Arbey

Publications and source records attributed to A. Arbey.

61 records · Page 4Linked to original sources

arXiv2009

Relic density and future colliders: inverse problem(s)

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 change the relic density constraints on the SUSY parameter space. Therefore one should be extremely careful when using the relic density to constrain supersymmetry as it could give misleading results, especially if combined with the future collider data. Alternatively, we will also show that combining the discoveries of the future colliders with relic density calculations can shed light on the inaccessible pre-BBN dark time physics. Finally we will present SuperIso Relic, a new relic density calculator code in Supersymmetry, which incorporates alternative cosmological models, and is publicly available.

hep-ph↗

arXiv2009

SuperIso Relic: A program for calculating relic density and flavor physics observables in Supersymmetry

We describe SuperIso Relic, a public program for evaluation of relic density and flavor physics observables in the minimal supersymmetric extension of the Standard Model (MSSM). SuperIso Relic is an extension of the SuperIso program which adds to the flavor observables of SuperIso the computation of all possible annihiliation and coannihilation processes of the LSP which are required for the relic density calculation. All amplitudes have been generated at the tree level with FeynArts/FormCalc, and widths of the Higgs bosons are computed with FeynHiggs at the two-loop level. SuperIso Relic also provides the possibility to modify the assumptions of the cosmological model, and to study their consequences on the relic density.

hep-ph↗

arXiv2008

Dark Energy vs. Dark Matter: Towards a Unifying Scalar Field?

The standard model of cosmology suggests the existence of two components, "dark matter" and "dark energy", which determine the fate of the Universe. Their nature is still under investigation, and no direct proof of their existences has emerged yet. There exist alternative models which reinterpret the cosmological observations, for example by replacing the dark energy/dark matter hypothesis by the existence of a unique dark component, the dark fluid, which is able to mimic the behaviour of both components. After a quick review of the cosmological constraints on this unifying dark fluid, we will present a model of dark fluid based on a complex scalar field and discuss the problem of the choice of the potential.

astro-ph↗

arXiv2008

Cosmological constraints on unifying Dark Fluid models

In the standard model of cosmology, dark matter and dark energy are presently the two main contributors to the total energy in the Universe. However, these two dark components are still of unknown nature, and many alternative explanations are possible. We consider here the so-called unifying dark fluid models, which replace dark energy and dark matter by a unique dark fluid with specific properties. We will analyze in this context recent observational data from supernovae of type Ia, large scale structures and cosmic microwave background, as well as theoretical results of big-bang nucleosynthesis, in order to derive constraints on the dark fluid parameters. We will also consider constraints from local scales, and conclude with a brief study of a scalar field dark fluid model.

astro-ph↗

arXiv2008

SUSY constraints from relic density: high sensitivity to pre-BBN expansion rate

The sensitivity of the lightest supersymmetric particle relic density calculation to the variation of the cosmological expansion rate before nucleosynthesis is discussed. We show that such a modification, even extremely modest and with no consequence on the cosmological observations, can greatly enhance the calculated relic density, and therefore change the constraints on the SUSY parameter space drastically. We illustrate this variation in two examples of SUSY models, and show that it is unsafe to use the lower bound of the WMAP limits in order to constrain supersymmetry. We therefore suggest to use only the upper value Omega_DM h^2 < 0.135.

hep-ph↗

arXiv2006

SN 2004aw: Confirming Diversity of Type Ic Supernovae

Optical and near-infrared observations of the Type Ic supernova (SN) 2004aw are presented, obtained from day -3 to day +413 with respect to the B-band maximum. The photometric evolution is characterised by a comparatively slow post-maximum decline of the light curves. The peaks in redder bands are significantly delayed relative to the bluer bands, the I-band maximum occurring 8.4 days later than that in B. With an absolute peak magnitude of -18.02 in the V band the SN can be considered fairly bright, but not exceptional. This also holds for the U through I bolometric light curve, where SN 2004aw has a position intermediate between SNe 2002ap and 1998bw. Spectroscopically SN 2004aw provides a link between a normal Type Ic supernova like SN 1994I and the group of broad-lined SNe Ic. The spectral evolution is rather slow, with a spectrum at day +64 being still predominantly photospheric. The shape of the nebular [O I] 6300,6364 line indicates a highly aspherical explosion. Helium cannot be unambiguously identified in the spectra, even in the near-infrared. Using an analytical description of the light curve peak we find that the total mass of the ejecta in SN 2004aw is 3.5-8.0 M_Sun, significantly larger than in SN 1994I, although not as large as in SN 1998bw. The same model suggests that about 0.3 M_Sun of {56}Ni has been synthesised in the explosion. No connection to a GRB can be firmly established.

astro-ph↗

arXiv2005

Unifying dark energy and dark matter with a scalar field

The standard model of cosmology considers the existence of two components of unknown nature, ``dark matter'' and ``dark energy'', which determine the cosmological evolution. Their nature remains unknown, and other models can also be considered. In particular, it may be possible to reinterpret the recent cosmological observations so that the Universe does not contain two fluids of unknown natures, but only one fluid with particular properties. After a brief review of constraints on this unifying ``dark fluid'', we will discuss a specific model of dark fluid based on a complex scalar fluid.

astro-ph↗