5,581 research outputs found
Matter parity as the origin of scalar Dark Matter
We extend the concept of matter parity to
non-supersymmetric theories and argue that is the natural explanation to
the existence of Dark Matter of the Universe. We show that the
non-supersymmetric Dark Matter must be contained in scalar 16 representation(s)
of thus the unique low energy Dark Matter candidates are -odd
complex scalar singlet(s) and inert scalar doublet(s) We have
calculated the thermal relic Dark Matter abundance of the model and shown that
its minimal form may be testable at LHC via the SM Higgs boson decays The PAMELA anomaly can be explained with the decays
induced via seesaw-like operator which is additionally suppressed by Planck
scale. Because the SM fermions are odd under matter parity too, the DM sector
is just our scalar relative.Comment: The origin of scalar DM is emphasized, version accepted by PR
Implications of the 125 GeV Higgs boson for scalar dark matter and for the CMSSM phenomenology
We study phenomenological implications of the ATLAS and CMS hint of a GeV Higgs boson for the singlet, and singlet plus doublet non-supersymmetric
dark matter models, and for the phenomenology of the CMSSM. We show that in
scalar dark matter models the vacuum stability bound on Higgs boson mass is
lower than in the standard model and the 125 GeV Higgs boson is consistent with
the models being valid up the GUT or Planck scale. We perform a detailed study
of the full CMSSM parameter space keeping the Higgs boson mass fixed to GeV, and study in detail the freeze-out processes that imply the observed
amount of dark matter. After imposing all phenomenological constraints except
for the muon we show that the CMSSM parameter space is divided
into well separated regions with distinctive but in general heavy sparticle
mass spectra. Imposing the constraint introduces severe tension
between the high SUSY scale and the experimental measurements -- only the
slepton co-annihilation region survives with potentially testable sparticle
masses at the LHC. In the latter case the spin-independent DM-nucleon
scattering cross section is predicted to be below detectable limit at the
XENON100 but might be of measurable magnitude in the general case of light dark
matter with large bino-higgsino mixing and unobservably large scalar masses.Comment: 17 pages, 7 figures. v3: same as published versio
Direct determination of neutrino mass parameters at future colliders
If the observed light neutrino masses are induced by their Yukawa couplings
to singlet right-handed neutrinos, natural smallness of those renders direct
collider tests of the electroweak scale neutrino mass mechanisms almost
impossible both in the case of Dirac and Majorana (seesaw of type I) neutrinos.
However, in the triplet Higgs seesaw scenario the smallness of light neutrino
masses may come from the smallness of B-L breaking parameters, allowing sizable
Yukawa couplings even for a TeV scale triplet. We show that, in this scenario,
measuring the branching fractions of doubly charged Higgs to different
same-charged lepton flavours at LHC and/or ILC experiments will allow one to
measure the neutrino mass parameters which neutrino oscillation experiments are
insensitive to, including the neutrino mass hierarchy, lightest neutrino mass
and Majorana phases.Comment: A mistake corrected, experimental errors revised, new references
added, conclusions unchange
Long-lived charged Higgs at LHC as a probe of scalar Dark Matter
We study inert charged Higgs boson production and decays at LHC
experiments in the context of constrained scalar dark matter model (CSDMM). In
the CSDMM the inert doublet and singlet scalar's mass spectrum is predicted
from the GUT scale initial conditions via RGE evolution. We compute the cross
sections of processes at the LHC and show that
for light the first one is dominated by top quark mediated 1-loop
diagram with Higgs boson in s-channel. In a significant fraction of the
parameter space are long-lived because their decays to predominantly
singlet scalar dark matter (DM) and next-to-lightest (NL) scalar, are suppressed by the small singlet-doublet mixing
angle and by the moderate mass difference
The experimentally measurable displaced vertex in decays to leptons
and/or jets and missing energy allows one to discover the signal over
the huge background. We propose benchmark points for studies of this
scenario at the LHC. If, however, are short-lived, the subsequent
decays necessarily produce additional
displaced vertices that allow to reconstruct the full decay chain.Comment: 15 pages, 5 figure
Dark Matter as the signal of Grand Unification
We argue that the existence of Dark Matter (DM) is a possible consequence of
GUT symmetry breaking. In GUTs like SO(10), discrete Z_2 matter parity
(-1)^{3(B-L)} survives despite of broken B-L, and group theory uniquely
determines that the only possible Z_2-odd matter multiplets belong to
representation 16. We construct the minimal non-SUSY SO(10) model containing
one scalar 16 for DM and study its predictions below M_{G}. We find that EWSB
occurs radiatively due to DM couplings to the SM Higgs boson. For thermal relic
DM the mass range M_{DM}\sim (0.1-1) TeV is predicted by model perturbativity
up to M_{G}. For M_{DM}\sim (1) TeV to explain the observed cosmic ray
anomalies with DM decays, there exists a lower bound on the spin-independent
direct detection cross section within the reach of planned experiments.Comment: DM direct detection cross section is corrected by adding s-quark
contribution which turned out to be the dominant one. The prediction is just
below the present CDMS and XENON10 bound. Extended version, RGE-s included,
new references adde
The Inert Doublet Model and Inelastic Dark Matter
The annual modulation observed by DAMA/NaI and DAMA/Libra may be interpreted
in terms of elastic or inelastic scattering of dark matter particles. In this
paper we confront these two scenarios within the framework of a very simple
extension of the Standard Model, the Inert Doublet Model (IDM). In this model
the dark matter candidate is a scalar, the lightest component of an extra Higgs
doublet. We first revisit the case for the elastic scattering of a light scalar
WIMP, M_DM~10 GeV, a scenario which requires that a fraction of events in DAMA
are channelled. Second we consider the possibility of inelastic Dark Matter
(iDM). This option is technically natural in the IDM, in the sense that the
mass splitting between the lightest and next-to-lightest neutral scalars may be
protected by a Peccei-Quinn (PQ) symmetry. We show that candidates with a mass
M_DM between ~535 GeV and ~50 TeV may reproduce the DAMA data and have a cosmic
abundance in agreement with WMAP. This range may be extended to candidates as
light as ~50 GeV if we exploit the possibility that the approximate PQ symmetry
is effectively conserved and that a primordial asymmetry in the dark sector may
survive until freeze-out.Comment: 16 pages, 7 figures. v2: minor changes and discussion on the
embedding in SO(10) added. v3: matches the published version in JCA
Effective Dark Matter Model: Relic density, CDMS II, Fermi LAT and LHC
The Cryogenic Dark Matter Search recently announced the observation of two
signal events with a 77% confidence level. Although statistically inconclusive,
it is nevertheless suggestive. In this work we present a model-independent
analysis on the implication of a positive signal in dark matter scattering off
nuclei. Assuming the interaction between (scalar, fermion or vector) dark
matter and the standard model induced by unknown new physics at the scale
, we examine various dimension-6 tree-level induced operators and
constrain them using the current experimental data, e.g. the WMAP data of the
relic abundance, CDMS II direct detection of the spin-independent scattering,
and indirect detection data (Fermi LAT cosmic gamma-ray), etc. Finally, the LHC
reach is also explored
Direct detection and CMB constraints on light DM scenario of top quark asymmetry and dijet excess at Tevatron
We study in detail the model by Isidori and Kamenik that is claimed to
explain the top quark forward-backward asymmetry at Tevatron, provide GeV-scale
dark matter (DM), and possibly improve the agreement between data and theory in
Tevatron W+jj events. We compute the DM thermal relic density, the
spin-independent DM-nucleon scattering cross section, and the cosmic microwave
background constraints on both Dirac and Majorana neutralino DM in the
parameter space that explains the top asymmetry. A stable light neutralino is
not allowed unless the local DM density is 3-4 times smaller than expected, in
which case Dirac DM with mass around 3 GeV may be possible, to be tested by the
Planck mission. The model predicts a too broad excess in the dijet distribution
and a strong modification of the missing E_T distribution in W+jj events.Comment: 4 pages, 4 figures; fig. 2 corrected, conclusions slightly changed,
matches published versio
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