321 research outputs found
A new viable region of the inert doublet model
The inert doublet model, a minimal extension of the Standard Model by a
second Higgs doublet, is one of the simplest and most attractive scenarios that
can explain the dark matter. In this paper, we demonstrate the existence of a
new viable region of the inert doublet model featuring dark matter masses
between Mw and about 160 GeV. Along this previously overlooked region of the
parameter space, the correct relic density is obtained thanks to cancellations
between different diagrams contributing to dark matter annihilation into gauge
bosons (W+W- and ZZ). First, we explain how these cancellations come about and
show several examples illustrating the effect of the parameters of the model on
the cancellations themselves and on the predicted relic density. Then, we
perform a full scan of the new viable region and analyze it in detail by
projecting it onto several two-dimensional planes. Finally, the prospects for
the direct and the indirect detection of inert Higgs dark matter within this
new viable region are studied. We find that present direct detection bounds
already rule out a fraction of the new parameter space and that future direct
detection experiments, such as Xenon100, will easily probe the remaining part
in its entirety.Comment: 27 pages, 16 figure
Sneutrino cold dark matter, a new analysis: relic abundance and detection rates
We perform a new and updated analysis of sneutrinos as dark matter
candidates, in different classes of supersymmetric models. We extend previous
analyses by studying sneutrino phenomenology for full variations of the
supersymmetric parameters which define the various models. We first revisit the
standard Minimal Supersymmetric Standard Model, concluding that sneutrinos are
marginally compatible with existing experimental bounds, including direct
detection, provided they compose a subdominant component of dark matter. We
then study supersymmetric models with the inclusion of right-handed fields and
lepton-number violating terms. Simple versions of the lepton-number-violating
models do not lead to phenomenology different from the standard case when the
neutrino mass bounds are properly included. On the contrary, models with
right-handed fields are perfectly viable: they predict sneutrinos which are
compatible with the current direct detection sensitivities, both as subdominant
and dominant dark matter components. We also study the indirect detection
signals for such successful models: predictions for antiproton, antideuteron
and gamma-ray fluxes are provided and compared with existing and future
experimental sensitivities. The neutrino flux from the center of the Earth is
also analyzed.Comment: 72 pages, 50 figures. The version on the archive has low-resolution
figures. The paper with high resolution figures may be found through
http://www.to.infn.it/~arina/papers or
http://www.to.infn.it/~fornengo/Research/paperlist.htm
Light neutralino in the MSSM: An update with the latest LHC results
We discuss the scenario of light neutralino dark matter in the minimal
supersymmetric standard model, which is motivated by the results of some of the
direct detection experiments --- DAMA, CoGENT, and CRESST. We update our
previous analysis with the latest results of the LHC. We show that new LHC
constraints disfavour the parameter region that can reproduce the results of
DAMA and CoGENT.Comment: 4 pages, 4 figures, to appear in the conference proceedings of TAUP
2011, Munich Germany, 5-9 September 201
Restudy on Dark Matter Time-Evolution in the Littlest Higgs model with T-parity
Following previous study, in the Littlest Higgs model (LHM), the heavy photon
is supposed to be a possible dark matter candidate and its relic abundance of
the heavy photon is estimated in terms of the Boltzman-Lee-Weinberg
time-evolution equation. The effects of the T-parity violation is also
considered. Our calculations show that when Higgs mass taken to be 300
GeV and don't consider T-parity violation, only two narrow ranges
GeV and GeV are tolerable with the
current astrophysical observation and if GeV, there must at
least exist another species of heavy particle contributing to the cold dark
matter. As long as the T-parity can be violated, the heavy photon can decay
into regular standard model particles and would affect the dark matter
abundance in the universe, we discuss the constraint on the T-parity violation
parameter based on the present data. Direct detection prospects are also
discussed in some detail.Comment: 13 pages, 11 figures include
Minimal Supersymmetric Inverse Seesaw: Neutrino masses, lepton flavour violation and LHC phenomenology
We study neutrino masses in the framework of the supersymmetric inverse
seesaw model. Different from the non-supersymmetric version a minimal
realization with just one pair of singlets is sufficient to explain all
neutrino data. We compute the neutrino mass matrix up to 1-loop order and show
how neutrino data can be described in terms of the model parameters. We then
calculate rates for lepton flavour violating (LFV) processes, such as , and chargino decays to singlet scalar neutrinos. The latter decays
are potentially observable at the LHC and show a characteristic decay pattern
dictated by the same parameters which generate the observed large neutrino
angles.Comment: 26 pages, 4 figures; added explanatory comments, final version for
publicatio
VDM: A model for Vector Dark Matter
We construct a model based on a new gauge symmetry and a discrete
symmetry under which the new gauge boson is odd. The model contains new
complex scalars which carry charge but are singlets of the Standard
Model. The symmetry is spontaneously broken but the symmetry is
maintained, making the new gauge boson a dark matter candidate. In the minimal
version there is only one complex scalar field but by extending the number of
scalars to two, the model will enjoy rich phenomenology which comes in various
phases. In one phase, CP is spontaneously broken. In the other phase, an
accidental symmetry appears which makes one of the scalars stable and
therefore a dark matter candidate along with the vector boson. We discuss the
discovery potential of the model by colliders as well as the direct dark matter
searches.Comment: 22 pages, 2 figure
Seesaw Extended MSSM and Anomaly Mediation without Tachyonic Sleptons
Superconformal anomalies provide an elegant and economical way to understand
the soft breaking parameters in SUSY models; however, implementing them leads
to the several undesirable features including: tachyonic sleptons and
electroweak symmetry breaking problems in both the MSSM and the NMSSM. Since
these two theories also have the additonal problem of massless neutrinos, we
have reconsidered the AMSB problems in a class of models that extends the NMSSM
to explain small neutrino masses via the seesaw mechanism. In a recent paper,
we showed that for a class of minimal left-right extensions, a built-in
mechanism exists which naturally solves the tachyonic slepton problem and
provides new alternatives to the MSSM that also have automatic R-parity
conservation. In this paper, we discuss how electroweak symmetry breaking
arises in this model through an NMSSM-like low energy theory with a singlet
VEV, induced by the structure of the left-right extension and of the right
magnitude. We then study the phenomenological issues and find: the LSP is an
Higgsino-wino mix, new phenomenology for chargino decays to the LSP, degenerate
same generation sleptons and a potential for a mild squark-slepton degeneracy.
We also discuss possible collider signatures and the feasibility of dark matter
in this model.Comment: 40 pages, 10 figures, 5 tables; v3: Added addendum and three new
references; v4: Added reference that was inadvertently omitte
Gamma Ray Lines from a Universal Extra Dimension
Indirect Dark Matter searches are based on the observation of secondary
particles produced by the annihilation or decay of Dark Matter. Among them,
gamma-rays are perhaps the most promising messengers, as they do not suffer
deflection or absorption on Galactic scales, so their observation would
directly reveal the position and the energy spectrum of the emitting source.
Here, we study the detailed gamma-ray energy spectrum of Kaluza--Klein Dark
Matter in a theory with 5 Universal Extra Dimensions. We focus in particular on
the two body annihilation of Dark Matter particles into a photon and another
particle, which produces monochromatic photons, resulting in a line in the
energy spectrum of gamma rays. Previous calculations in the context of the five
dimensional UED model have computed the line signal from annihilations into
\gamma \gamma, but we extend these results to include \gamma Z and \gamma H
final states. We find that these spectral lines are subdominant compared to the
predicted \gamma \gamma signal, but they would be important as follow-up
signals in the event of the observation of the \gamma \gamma line, in order to
distinguish the 5d UED model from other theoretical scenarios.Comment: 21 pages, 6 figure
The Maximal Inverse Seesaw from Operator and Oscillating Asymmetric Sneutrino Dark Matter
The maximal supersymmetric inverse seesaw mechanism (MSIS)
provides a natural way to relate asymmetric dark matter (ADM) with neutrino
physics. In this paper we point out that, MSIS is a natural outcome if one
dynamically realizes the inverse seesaw mechanism in the next-to minimal
supersymmetric standard model (NMSSM) via the dimension-five operator
, with the NMSSM singlet developing TeV scale VEV; it
slightly violates lepton number due to the suppression by the fundamental scale
, thus preserving maximally. The resulting sneutrino is a
distinguishable ADM candidate, oscillating and favored to have weak scale mass.
A fairly large annihilating cross section of such a heavy ADM is available due
to the presence of singlet.Comment: journal versio
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