AlterBBN: A program for calculating the BBN abundances of the elements in alternative cosmologies

We describe AlterBBN, a public C program for evaluating the abundances of the elements generated by Big-Bang nucleosynthesis (BBN). This program enables the user to compute the abundances of the elements in the standard model of cosmology, and additionally provides possibilities to alter the assumptions of the cosmological model in order to study their consequences on the abundances of the elements. In particular the baryon-to-photon ratio and the effective number of neutrinos, as well as the expansion rate and the entropy content of the Universe during BBN can be modified in AlterBBN. Such features allow the user to test the cosmological models by confronting them to BBN constraints. A presentation of the physics of BBN and the features of AlterBBN is provided here under the form of a manual.Comment: 15 pages, 1 figure, 1 table. AlterBBN can be obtained from https://alterbbn.hepforge.org

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.Comment: 4 pages, 4 figures, to appear in the XXIst IAP Colloquium "Mass Profiles and Shapes of Cosmological Structures", Paris 4-9 July 2005, France, (Eds.) G. Mamon, F. Combes, C. Deffayet, B. Fort, EAS Publications Serie

LHC and ILC Data and the Early Universe Properties

With the start-up of the LHC, we can hope to find evidences for new physics beyond the Standard Model, and particle candidates for dark matter. Determining the parameters of the full underlying theory will be a long process requiring the combination of LHC and ILC data, flavor physics constraints, and cosmological observations. However, the Very Early Universe properties, from which the relic particles originate, are poorly known, and the relic density calculation can be easily falsified by hidden processes. We consider supersymmetry and show that determining the underlying particle physics parameters will help understanding the Very Early Universe properties.Comment: 6 pages, 2 figures, contribution to the proceedings of the workshop "LC09: e+e- Physics at the TeV Scale and the Dark Matter Connection", Perugia, September 21 - 24, 2009, Italy. v2: reference adde

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.Comment: 8 pages, 5 figures, contribution to the proceedings of the conference "Invisible Universe", Paris, June 29 - July 3, 2009, Franc

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.Comment: 6 pages, 2 figures, contribution to the proceedings of the July 2008 CRAL-IPNL conference "Dark Energy and Dark Matter

Complementarity of direct and indirect searches in the pMSSM

We explore the pMSSM parameter space in view of the constraints from SUSY and monojet searches at the LHC, from Higgs data and flavour physics observables, as well as from dark matter searches. We show that whilst the simplest SUSY scenarios are already ruled out, there are still many possibilities left over in the pMSSM. We discuss the complementarity between different searches and consistency checks which are essential in probing the pMSSM and will be even more important in the near future with the next round of data becoming available.Comment: 6 pages, 9 figures. Contribution to the proceedings of the Fifth Capri Workshop on the interplay of flavour physics with electroweak symmetry breaking and dark matter, Capri, May 201

Light neutralino dark matter in MSSM

Three dark matter direct detection experiments, DAMA, COGENT and CRESST, have reported a possible signal of WIMP interaction corresponding to very light particles, close to the edge of the XENON 100 and CDMS sensitivity. Imposing the latest constraints from colliders, flavour physics, electroweak precision tests and direct and indirect dark matter searches, we show that viable MSSM scenarios with a light neutralino, in agreement with all the present data, are feasible. An analysis of the characteristics of the resulting scenarios will be presented.Comment: 6 pages, 2 figures, contribution to the ICHEP 2012 Conference proceedings, 4-11 July 2012, Melbourne, Australi

Implications of LHC Higgs and SUSY searches for MSSM

The implications of the LHC SUSY searches as well as the discovery of a new bosonic state compatible with the lightest Higgs boson will be discussed in the context of constrained and general MSSM scenarios. Exploring the MSSM through the Higgs sector is an alternative and complementary path to direct searches, and tight constraints on the MSSM parameter space can be obtained.Comment: 7 pages, 5 figures, contribution to the ICHEP 2012 Conference proceedings, 4-11 July 2012, Melbourne, Australi

An update of the constraints on the phenomenological MSSM from the new LHC Higgs results

Updated results on the search of Higgs bosons at the LHC with up to 17/fb of data have just been presented by the ATLAS and CMS collaborations. New constraints are provided by the LHCb and XENON experiments with the observation of the rare decay B_s -> mu+mu- and new limits on dark matter direct detection. In this paper, we update and extend the results on the implications of these data on the phenomenological Minimal Supersymmetric extension of the Standard Model (pMSSM) by using high statistics, flat scans of its 19 parameters. The new LHC data on bb and tau tau decays of the lightest Higgs state and the new CMS limits from the tau tau searches for the heavier Higgs states set stronger constraints on the pMSSM parameter space.Comment: 14 pages, 8 figures. This update is based on results presented at HCP 2012 and the December 2012 CERN Council LHC Jamboree. It features larger scan statistics and additional plot

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.Comment: 11 pages, 1 figure, 1 tabl