[Show abstract][Hide abstract] ABSTRACT: We consider a general class of models in which dark matter is a composite
baryonic and antibaryonic particle of some hidden vector-like strong gauge
theory. The model building provides simple answers to two basic questions:
Annihilation between dark baryon and antibaryon saturates the unitarity bound,
which in thermal freeze out predicts the scale of dark matter particle to be
about 150 TeV. And the dark matter stability is a result of the accidental dark
baryon number, which can still be violated by operators suppressed by large
scales, leading to tiny decay rate. We show that annihilation between dark
baryon and anti-baryon seems difficult to be detected in the galaxy center in
the near future. On the other hand in the minimal model of $SU(3)$ hidden
strong gauge group with a Planck scale suppression, the dark matter life time
happens to be marginal to the current detection bound, and can explain the
current AMS-02 antiproton results.
[Show abstract][Hide abstract] ABSTRACT: The AMS-02 collaboration has recently reported the antiproton to proton ratio
with improved accuracy. In view of uncertainties of the production and the
propagation of the cosmic rays, the observed ratio is still consistent with the
secondary astrophysical antiproton to proton ratio. However, it is nonetheless
enticing to examine whether the observed spectrum can be explained by a
strongly motivated dark matter, the wino dark matter. As we will show, we find
that the antiproton flux from the wino annihilation can explain the observed
spectrum well for its mass range 2.5-3 TeV. The fit to data becomes
particularly well compared to the case without the annihilation for the thermal
wino dark matter case with a mass about 3 TeV. The ratio is predicted to be
quickly decreased at the energy several hundreds of GeV, if this possibility is
true, and it will be confirmed or ruled out in near future when the AMS-02
experiment accumulates enough data at this higher energy region.
Physical Review D 04/2015; 91(11). DOI:10.1103/PhysRevD.91.111701 · 4.64 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Various types of electroweak-interacting particles, which have non-trivial
charges under the $\mathrm{SU}(2)_L \times \mathrm{U}(1)_Y$ gauge symmetry,
appear in various extensions of the Standard Model. These particles are good
targets of future lepton colliders, such as the International Linear Collider
(ILC), the Compact LInear Collider (CLIC) and the Future Circular Collider of
electrons and positrons (FCC-ee). An advantage of the experiments is that, even
if their beam energies are below the threshold of the production of the new
particles, quantum effects of the particles can be detected through high
precision measurements. We estimate the capability of future lepton colliders
to probe electroweak-interacting particles through the quantum effects, with
particular focus on the wino, the Higgsino and the so-called minimal dark
matters, and found that a particle whose mass is greater than the beam energy
by 100-1000 GeV is detectable by measuring di-fermion production cross sections
with $O(0.1)$\% accuracy. In addition, with the use of the same analysis, we
also discuss the sensitivity of the future colliders to model independent
higher dimensional operators, and found that the cutoff scales corresponding to
the operators can be probed up to a few ten TeV.
Journal of High Energy Physics 04/2015; 2015(9). DOI:10.1007/JHEP09(2015)105 · 6.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Under rather generic assumptions, we show that in the asymmetric dark matter
(ADM) scenario, the sign of the B-L asymmetry stored in the dark matter sector
and the standard model sector are always the same. One particularly striking
consequence of this result is that, when the dark matter decays or annihilates
in the present universe, the resulting final state always involves an
anti-neutrino. As a concrete example of this, we construct a composite ADM
model and explore the feasibility of detecting such an anti-neutrino signal in
atmospheric neutrino detectors.
[Show abstract][Hide abstract] ABSTRACT: We revisit the decaying wino dark matter scenario in the light of the updated
positron fraction, electron and positron fluxes in cosmic ray recently reported
by the AMS-02 collaboration. We show the AMS-02 results favor the mass of the
wino dark matter at around a few TeV, which is consistent with the prediction
on the wino mass in the pure gravity mediation model.
Physics Letters B 09/2014; 741. DOI:10.1016/j.physletb.2014.12.016 · 6.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We explore a singlet Majorana fermion dark matter candidate using an
effective field theory (EFT) framework, respecting the relations imposed by the
standard model $SU(3)_C \times SU(2)_L \times U(1)_Y$ gauge invariance among
different couplings. All operators of dimension-5 and dimension-6, forming a
complete basis, are taken into account at the same time, keeping in view
ultraviolet completions which can give rise to more than one operator at a
time. If in addition CP-conservation is assumed, the remaining parameter space,
where an EFT description is valid, is found to be rather restricted after
imposing constraints from relic abundance, direct, indirect and collider
searches. On including the CP-violating dimension-5 operator,
$(\overline{\chi}i \gamma_5 \chi) (H^\dagger H)$, a significantly larger
parameter space opens up. We use the profile likelihood method to map out the
remaining landscape of such a DM scenario. The reach of future searches using
ton-scale direct detection experiments, an $e^+ e^-$ collider like the proposed
ILC and limits from future gamma-ray observations are also estimated.
Journal of High Energy Physics 07/2014; 2014(10). DOI:10.1007/JHEP10(2014)155 · 6.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We discuss the indirect detection of the wino dark matter utilizing gamma-ray
observations of dwarf spheroidal galaxies (dSphs). After carefully reviewing
current limits with particular attention to astrophysical uncertainties, we
show prospects of the wino mass limit in future gamma-ray observation by the
Fermi-LAT and the GAMMA-400 telescopes. We find that the improvement of the
so-called $J$-factor of both the classical and the ultra-faint dSphs will play
a crucial role to cover whole mass range of the wino dark matter. For example,
with $\delta (\log_{10}J) = 0.1$ for both the classical and the ultra-faint
dSphs, whole wino dark matter mass range can be covered by 15 years and 10
years data at the Fermi-LAT and GAMMA-400 telescopes, respectively.
Journal of High Energy Physics 05/2014; 2014(7). DOI:10.1007/JHEP07(2014)080 · 6.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The large value of the tensor-to-scalar ratio in the cosmic microwave
background radiation reported by the BICEP2 collaboration gives strong impact
on models of supersymmetry (SUSY). The large ratio indicates inflation with a
high-energy scale and thus a high reheating temperature in general, and various
SUSY models suffer from the serious gravitino and Polonyi problems. In this
article, we discuss a class of the high-scale SUSY breaking models which are
completely free from those problems. With especially focusing on the dark
matter relic abundance, we examine how the BICEP2 result narrows down the
parameter space of the models, assuming the simplest chaotic inflation model.
We find that the mass of the dark matter is predicted to be less than about 1
TeV thanks to the non-thermal production in the early universe through the
decay of abundant gravitinos produced after the reheating process. We also
discuss implications in some details to dark matter searches at collider and
indirect dark matter detection experiments.
Journal of High Energy Physics 03/2014; 2014(7). DOI:10.1007/JHEP07(2014)093 · 6.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The high-scale supersymmetry (SUSY) breaking scenario is now attracting many
attentions, because it is consistent with almost all experiments of particle
physics, astrophysics, and cosmology performed so far: e.g. it is possible to
explain the Higgs mass of about 126GeV and contains WIMP dark matter
candidates. In the scenario, gauginos are predicted to be around the TeV scale,
and thus within a kinematically accessible range of near future experiments.
Calculation of the thermal relic abundance for gaugino (bino or wino) dark
matter is then of particular importance in order to clarify its mass consistent
with cosmology and to determine future directions for exploring the high-scale
SUSY breaking scenario. In this article, we calculate the abundance of the
gaugino dark matter, with especially focusing on various coannihilations
between gauginos, which has not been extensively studied so far. Our
calculation involves the Sommerfeld effect on wino and gluino annihilations,
which is known to give significant contributions to their cross sections. Based
on obtained results, we discuss some implications to gaugino searches at
collider and indirect detection experiments of dark matter.
Physical Review D 03/2014; 89(11). DOI:10.1103/PhysRevD.89.115021 · 4.64 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The observed Higgs boson mass poses a new puzzle in addition to the
longstanding problem of the origin of the electroweak scale; the shallowness of
the Higgs potential. The Higgs quartic coupling even seems to vanish at around
the Planck scale within the uncertainties of the top quark mass and the strong
gauge coupling. We show that the shallowness of the Higgs potential might be an
outcome of supersymmetry breaking at around the Planck scale. There, the
electroweak fine-tuning in the Higgs quadratic terms leads to an almost
vanishing quartic coupling at around the Planck scale.
Physics Letters B 12/2013; 732. DOI:10.1016/j.physletb.2014.03.041 · 6.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We study phenomenological aspects of the bino-wino co-annihilation scenario
in high-scale supersymmetry breaking models. High-scale SUSY breaking scenarios
are considered to be promising possibility after the discovery of the Higgs
boson with a mass around 126 GeV. In this paper, we discuss the bino lightest
supersymmetric particle (LSP) accompanied by the at most around 30 GeV heavier
wino. With the suitable mass splitting between the bino and the wino, the bino
LSP has the correct relic abundance of dark matter. For the smaller mass
splitting, the late-time decay of the gravitino can provide the correct
abundance of the bino dark matter. It is extremely challenging to find signals
from the bino dark matter in direct and indirect detections. By utilizing
multi-jets plus missing transverse momentum events at the LHC, we can
constraint the gluino mass and thus probe the bino-wino co-annihilation
scenario indirectly. The collider experiment, however, can not search the bino
dark matter directly. In this paper, we suggest the direct probe of the bino
dark matter. We show that the bino dark matter leaves imprints on the
small-scale matter power spectrum when the bino dark matter is produced by the
decay of the gravitino. The non-thermal bino dark matter behaves as mixed
(cold+warm) dark matter.
Physical Review D 11/2013; 89(12). DOI:10.1103/PhysRevD.89.123506 · 4.64 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Asymmetric dark matter (ADM) has been an attractive possibility attempting to
explain the observed ratio of baryon to dark matter abundance in the universe.
While a bosonic ADM is constrained by the limits from existence of old neutron
stars, a fermionic ADM requires an additional light particle in order to
annihilate its symmetric component in the early universe. We revisit the
phenomenology of a minimal GeV scale fermionic ADM model including a light
scalar state. The current constraints on this scenario from cosmology, dark
matter direct detection, flavour physics and collider searches are investigated
in detail. We estimate the future reach on the model parameter space from
next-generation dark matter direct detection experiments, Higgs boson property
measurements and search for light scalars at the LHC, as well as the
determination of Higgs invisible branching ratio at the proposed ILC.
Journal of High Energy Physics 06/2013; 2013(10). DOI:10.1007/JHEP10(2013)032 · 6.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The AMS-02 collaboration has recently reported an excess of the cosmic-ray
positron fraction, which turned out to be consistent with previous results
reported by the PAMELA and Fermi-LAT collaborations. A decaying dark matter
with the mass around 1 TeV can be responsible for the excess of the positron
fraction when it is interpreted as a dark matter signal. Interestingly, the
pure gravity mediation model provides such a dark matter, namely an almost pure
neutral wino dark matter, when a tiny R-parity violation through $LLE^c$
interactions is introduced. We show that the decaying wino dark matter well
reproduces the energy spectrum of the fraction with being consistent with
constraints from cosmic-ray anti-proton and gamma-ray observations.
Journal of High Energy Physics 05/2013; 2013(7). DOI:10.1007/JHEP07(2013)063 · 6.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The AMS-02 collaboration has recently reported an excess of cosmic-ray
positron fractions, which is consistent with previous results at PAMELA
and Fermi-LAT experiments. The result indicates the existence of new
physics phenomena to provide the origin of the energetic cosmic-ray
positron. We pursue the possibility that the enhancement of the positron
fraction is due to the decay of gravitino dark matter. We discuss that
such a scenario viably fits into the models in which the soft SUSY
breaking parameters are dominantly from gauge-mediation mechanism with
superparticle masses of around 10 TeV. Our scenario is compatible with
~126 GeV Higgs boson, negative searches for SUSY particles, and
non-observation of anomalous FCNC processes. We also point out that the
scenario will be tested in near future by measuring the electric dipole
moment of the electron and the lepton flavor violating decay of the
muon.
Journal of High Energy Physics 04/2013; 2013(8). DOI:10.1007/JHEP08(2013)029 · 6.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A monochromatic line in the cosmic neutrino spectrum would be a smoking gun
signature of dark matter. It is intriguing that the IceCube experiment has
recently reported two PeV neutrino events with energies that may be equal up to
experimental uncertainties, and which have a probability of being a background
fluctuation estimated to be less than a percent. Here we explore prospects for
these events to be the first indication of a monochromatic line signal from
dark matter. While measurable annihilation signatures would seem to be
impossible at such energies, we discuss the dark matter quantum numbers,
effective operators, and lifetimes which could lead to an appropriate signal
from dark matter decays. We will show that the set of possible decay operators
is rather constrained, and will focus on several viable candidates which could
explain the IceCube events; R-parity violating gravitinos, hidden sector gauge
bosons, and singlet fermions in an extra dimension. In essentially all cases we
find that a PeV neutrino line signal from dark matter would be accompanied by a
potentially observable continuum spectrum of neutrinos rising towards lower
energies.
[Show abstract][Hide abstract] ABSTRACT: Here, we give a broad overview of the more natural spectra allowed by the LHC
when UDD R-parity violation is allowed. Because R-parity violation removes the
missing energy signals in colliders, the experimental constraints on the
gluino, stops, sbottoms and higgsinos are relatively mild. We also show that
UDD R-parity violation and lepton number conservation can be made consistent
with grand unification. This feat is achieved through the product unification,
SU(5) X U(3). In this model, mixing of the SM quarks with additional quark like
particles charged under the U(3) generate a UDD R-parity violating operator.
Furthermore, these models are also capable of generating a "natural" spectra.
The emergence of these more natural low-scale spectra relies heavily on the
fact that the gaugino masses are non-universal, a natural consequence of
product unification.
[Show abstract][Hide abstract] ABSTRACT: The recent result of the higgs search at the LHC experiment has lead to more
attention to the supersymmetric standard models with heavy sfermions. Among
them, the models with the almost pure wino being the lightest supersymmetric
particle (LSP) have been widely discussed due to their success in providing a
consistent dark matter candidate. The notable phenomenological feature of the
wino LSP is the degeneracy with its charged SU(2)_L partner (the charged wino)
in mass. The tiny mass splitting makes the charged wino long-lived, which
allows us to detect the wino production at the LHC experiment by searching for
the disappearing charged tracks inside the detectors. Since the reach of the
experiment is sensitive to the mass splitting, it is mandatory to estimate it
very precisely. We therefore perform a full calculation of the mass splitting
at two-loop level, and find that the splitting is reduced by a few MeV compared
to the one-loop calculation. This reduction leads to about a 30 % longer
lifetime of the charged wino, with which the current constraint on the wino
mass by the ATLAS experiment is improved by about 10 %.
[Show abstract][Hide abstract] ABSTRACT: Present and future expected limits on interactions between dark matter and
various quarks are thoroughly investigated in a model-independent way. In
particular, the constraints on the interactions from the Large Hadron Collider
(LHC) experiment are carefully considered with focusing on mono jet + missing
transverse energy, mono b-jet + missing transverse energy, and top quark(s) +
missing transverse energy channels. Model-independent upper limits (expected
limits) on the cross section times acceptance for non-standard model events are
derived at 7 TeV (8 or 14 TeV) running of the LHC experiment. With assuming
that the dark matter is a singlet real scalar or a singlet Majorana fermion, we
also put constraints on several operators describing its interactions with up,
down, strange, charm, bottom and top quarks. These constraints are compared to
those obtained by cosmological and astrophysical observations of the dark
matter.
Journal of High Energy Physics 12/2012; 2013(4). DOI:10.1007/JHEP04(2013)031 · 6.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In the framework of gauge mediation models, we investigate scenarios with
heavy squarks and light sleptons, motivated by the recent discovery of the
Higgs boson and the deviation of the muon anomalous magnetic moment (g-2) from
the SM prediction. We show that only models with a messenger multiplet in the
adjoint representation of SU(5) GUT gauge group are the unique possibility that
sleptons are light enough to explain the muon g-2 in the minimal setup. We also
show that, if there is an additional source of the Higgs soft masses, the muon
g-2 can be explained with messenger multiples in the fundamental representation
of SU(5) with the help of the light higgsino. Some phenomenological aspects of
these models are also discussed.
Journal of High Energy Physics 10/2012; 2013(3). DOI:10.1007/JHEP03(2013)078 · 6.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We study how "warm" the wino dark matter is when it is non-thermally produced
by the decays of the gravitino in the early Universe. We clarify the energy
distribution of the wino at the decay of the gravitino and the energy loss
process after their production. By solving the Boltzmann equation, we show that
a sizable fraction of the wino dark matter can be "warm" for the wino mass
m_{\tilde w} \sim 100-500 GeV. The "warmness" of the wino dark matter leaves
imprints on the matter power spectra and may provide further insights on the
origin of dark matter via the future 21 cm line survey. Our calculations can be
applied to other non-thermal wino production scenarios such as the wino dark
matter produced by the decay of the moduli fields.