1,134 research outputs found
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
The Higgs boson, Supersymmetry and Dark Matter: Relations and Perspectives
The discovery of a light Higgs boson at the LHC opens a broad program of
studies and measurements to understand the role of this particle in connection
with New Physics and Cosmology. Supersymmetry is the best motivated and most
thoroughly formulated and investigated model of New Physics which predicts a
light Higgs boson and can explain dark matter. This paper discusses how the
study of the Higgs boson connects with the search for supersymmetry and for
dark matter at the LHC and at a future collider and with dedicated
underground dark matter experiments.Comment: 7 pages, 5 figure
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
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
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
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
Higgs Production in Neutralino Decays in the MSSM - The LHC and a Future e+e- Collider
The search for the production of weakly-interacting SUSY particles at the LHC
is crucial for testing supersymmetry in relation to dark matter. Decays of
neutralinos into Higgs bosons occur over some significant part of the SUSY
parameter space and represent the most important source of boson production
in SUSY decay chains in the MSSM. We study h production in neutralino decays
using scans of the phenomenological MSSM. Whilst in constrained MSSM scenarios
the decay chi^0_2 -> h chi^0_1 is the dominant channel, this does not hold in
more general MSSM scenarios. On the other hand, the chi^0_2,3 -> h chi^0_1
decays remain important and are highly complementary to multi-lepton final
states in the LHC searches. The perspectives for the LHC analyses at 8 and 14
TeV as well as the reach of an e+e- collider at 0.5, 1, 1.5 and 3 TeV are
discussed.Comment: 11 pages, 13 figure
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