74 research outputs found
LikeDM: likelihood calculator of dark matter detection
With the large progress in searches for dark matter (DM) particles with
indirect and direct methods, we develop a numerical tool that enables fast
calculations of the likelihoods of specified DM particle models given a number
of observational data, such as charged cosmic rays from space-borne experiments
(e.g., PAMELA, AMS-02), gamma-rays from the Fermi space telescope, and
underground direct detection experiments. The purpose of this tool --- LikeDM,
likelihood calculator for dark matter detection --- is to bridge the gap
between a particle model of DM and the observational data. The intermediate
steps between these two, including the astrophysical backgrounds, the
propagation of charged particles, the analysis of Fermi gamma-ray data, as well
as the DM velocity distribution and the nuclear form factor, have been dealt
with in the code. We release the first version (v1.0) focusing on the
constraints from indirect detection of DM with charged cosmic and gamma rays.
Direct detection will be implemented in the next version. This manual describes
the framework, usage, and related physics of the code. The code LikeDM can be
download from https://likedm.hepforge.org/Comment: v2, published in Computer Physics Communications, "LikeDM can be
download from https://likedm.hepforge.org/
Constraining dark matter capture and annihilation cross sections by searching for neutrino signature from the Earth core
We study the sensitivity of IceCube/DeepCore detector to dark matter
annihilations in the Earth core. We focus on annihilation modes , and . Both track and
cascade events are considered in our analysis. By fixing the dark matter
annihilation cross section at some nominal
values, we study the sensitivity of IceCube/DeepCore detector to dark matter
spin-independent cross section for ranging from
few tens of GeV to 10 TeV. This sensitivity is compared with the existing
IceCube 79-string constraint on the same cross section, which was obtained by
searching for dark matter annihilations in the Sun. We compare this sensitivity
to dark matter direct detection results as well, in particular the XENON100
(2012) limit and the parameter regions preferred by DAMA and CRESST-II
experiments. We also present IceCube/DeepCore sensitivity to as a function of by fixing at XENON100 (2012) and XENON1T limits, respectively. This sensitivity is
compared with the preferred dark matter parameter range derived from the
combined fitting to PAMELA and AMS02 positron fraction data. We conclude that
the search for dark matter annihilations in the Earth core provides competitive
constraints on and in the
case of low-mass dark matter. Particularly, the expected constraint on
\sigsip for 5 years of data taking in IceCube/DeepCore is more stringent than
the current IceCube 79-string limit mentioned above.Comment: 23 pages, 8 figure
Effective Theory of WIMP Dark Matter supplemented by Simplified Models: Singlet-like Majorana fermion case
We enumerate the set of simplified models which match onto the complete set
of gauge invariant effective operators up to dimension six describing
interactions of a singlet-like Majorana fermion dark matter with the standard
model. Tree level matching conditions for each case are worked out in the large
mediator mass limit, defining a one to one correspondence between the effective
operator coefficients and the simplified model parameters for weakly
interacting models. Utilizing such a mapping, we compute the dark matter
annihilation rate in the early universe, as well as other low-energy
observables like nuclear recoil rates using the effective operators, while the
simplified models are used to compute the dark matter production rates at high
energy colliders like LEP, LHC and future lepton colliders. Combining all
relevant constraints with a profile likelihood analysis, we then discuss the
currently allowed parameter regions and prospects for future searches in terms
of the effective operator parameters, reducing the model dependence to a
minimal level. In the parameter region where such a model-independent analysis
is applicable, and leaving aside the special dark matter mass regions where the
annihilation proceeds through an s-channel Z or Higgs boson pole, the current
constraints allow effective operator suppression scales () of the
order of a few hundred GeV for dark matter masses 20 GeV at
C.L., while the maximum allowed scale is around TeV for . An estimate of the future reach of ton-scale direct
detection experiments and planned electron-positron colliders show that most of
the remaining regions can be probed, apart from dark matter masses near half of
the Z-boson mass (with ) and those
beyond the kinematic reach of the future lepton colliders.Comment: 30 pages, 6 figure
A generic method to constrain the dark matter model parameters from Fermi observations of dwarf spheroids
Observation of gamma-rays from dwarf galaxies is an effective way to search
for particle dark matter. Using 4-year data of Fermi-LAT observations on a
series of Milky Way satellites, we develop a general way to search for the
signals from dark matter annihilation in such objects. Instead of giving prior
information about the energy spectrum of dark matter annihilation, we bin the
Fermi-LAT data into several energy bins and build a likelihood map in the
"energy bin - flux" plane. The final likelihood of any spectrum can be easily
derived through combining the likelihood of all the energy bins. It gives
consistent result with that directly calculated using the Fermi Scientific
Tool. This method is very efficient for the study of any specific dark matter
models with gamma-rays. We use the new likelihood map with Fermi-LAT 4 year
data to fit the parameter space in three representative dark matter models: i)
toy dark matter model, ii) effective dark matter operators, and iii)
supersymmetric neutralino dark matter.Comment: Matches JCAP accepted version, 8 pages, 6 figure
Singlet Majorana fermion dark matter: a comprehensive analysis in effective field theory
We explore a singlet Majorana fermion dark matter candidate using an
effective field theory (EFT) framework, respecting the relations imposed by the
standard model 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,
, 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 collider like the proposed
ILC and limits from future gamma-ray observations are also estimated.Comment: 36 pages, 7 figures; v2 : comments and references added, matches
version to appear in JHE
Sensitivities of IceCube DeepCore Detector to Signatures of Low-Mass Dark Matter in the Galactic Halo
We discuss the event rate in DeepCore array due to neutrino flux produced by
annihilations and decays of galactic dark matter. This event rate is calculated
with a 10 GeV threshold energy, which is smaller than the threshold energy
taken in previous works. Taking into account the background event rate due to
the atmospheric neutrino flux, we evaluate the sensitivity of DeepCore array
for probing dark matter annihilation cross section and decay time. The
sensitivity studies include the annihilation modes $\chi\chi\to b\bar{b}, \
\tau^+ \tau^-\mu^+\mu^-\nu\bar{\nu}\chi\to
b\bar{b}, \ \tau^+ \tau^-\mu^+\mu^-\nu\bar{\nu}$. We compare our
results with corresponding constraints derived from observations of WMAP, ACT
and Fermi-LAT.Comment: matches the published versio
Shedding Light on Dark Matter with Fermi LAT Data on Gamma Rays
The diffuse Galactic gamma-ray data from the region of the
Galactic Center has been collected by the LAT instrument on the
Fermi Gamma-Ray Space Telescope. In this paper we argue that it may be able
to provide an unambiguous evidence of originating, in addition to known
astrophysical sources, from dark matter annihilations in the halo,
independently of the mass and other properties of the dark matter particle. We
also show that the recently released high precision data from mid-latitudes is
already providing an upper bound, albeit still a weak one, on the cuspiness of
the dark matter density profile as a function of the mass of the dark matter
assumed to be a stable neutralino of minimal supersymmetry.Comment: 8 page
Non-abelian Dark Matter Solutions for Galactic Gamma-ray Excess and Perseus 3.5 keV X-ray Line
We attempt to explain simultaneously the Galactic center gamma-ray excess and
the 3.5 keV X-ray line from the Perseus cluster based on a class of non-abelian
DM models, in which the dark matter and an excited state comprise a
"dark" doublet. The non-abelian group kinetically mixes with the
standard model gauge group via dimensions-5 operators. The dark matter
particles annihilate into standard model fermions, followed by fragmentation
and bremsstrahlung, and thus producing a continuous spectrum of gamma-rays. On
the other hand, the dark matter particles can annihilate into a pair of excited
states, each of which decays back into the dark matter particle and an X-ray
photon, which has an energy equal to the mass difference between the dark
matter and the excited state, which is set to be 3.5 keV. The large hierarchy
between the required X-ray and -ray annihilation cross-sections can be
achieved by a very small kinetic mixing between the SM and dark sector, which
effectively suppresses the annihilation into the standard model fermions but
not into the excited state.Comment: v3: references and clarifications added, conclusions unchanged,
version accepted by JCA
The impact of propagation uncertainties on the potential Dark Matter contribution to the Fermi LAT mid-latitude gamma-ray data
We investigate the extent to which the uncertainties associated with the
propagation of Galactic cosmic rays impact upon estimates for the gamma-ray
flux from the mid-latitude region. We consider contributions from both standard
astrophysical background (SAB) processes as well as resolved point sources. We
have found that the uncertainties in the total gamma-ray flux from the
mid-latitude region relating to propagation parameter values consistent with
local B/C and Be10/Be9 data dominate by 1-2 orders of magnitude. These
uncertainties are reduced to less than an order of magnitude when the
normalisations of the SAB spectral components are fitted to the corresponding
Fermi LAT data. We have found that for many propagation parameter
configurations (PPCs) our fits improve when an extragalactic background (EGB)
component is simultaneously fitted to the data. We also investigate the
improvement in our fits when a flux contribution from neutralino dark matter
(DM), described by the Minimal Supersymmetric Standard Model, was
simultaneously fitted to the data. We consider three representative cases of
neutralino DM for both Burkert and Einasto DM density profiles, in each case
simultaneously fitting a boost factor of the DM contribution together with the
SAB and EGB components. We have found that for several PPCs there are
significant improvements in our fits, yielding both substantial EGB and DM
components, where for a few of these PPCs the best-fit EGB component is
consistent with recent estimates by the Fermi Collaboration.Comment: V2: 25 pages, 9 figures and 13 tables. Replaced to match version
accepted for publication in PRD. Major revisions to address referee's
comment
G2HDM : Gauged Two Higgs Doublet Model
A novel model embedding the two Higgs doublets in the popular two Higgs
doublet models into a doublet of a non-abelian gauge group is
presented. The Standard Model right-handed fermion singlets are
paired up with new heavy fermions to form doublets, while
left-handed fermion doublets are singlets under . Distinctive features
of this anomaly-free model are: (1) Electroweak symmetry breaking is induced
from spontaneous symmetry breaking of via its triplet vacuum
expectation value; (2) One of the Higgs doublet can be inert, with its neutral
component being a dark matter candidate as protected by the gauge
symmetry instead of a discrete symmetry in the usual case; (3) Unlike
Left-Right Symmetric Models, the complex gauge fields (along with other complex scalar fields) associated with the
do {\it not} carry electric charges, while the third component
can mix with the hypercharge gauge field and the third
component of ; (4) Absence of tree level flavour changing neutral
current is guaranteed by gauge symmetry; and {\it etc}. In this work, we
concentrate on the mass spectra of scalar and gauge bosons in the model.
Constraints from previous data at LEP and the Large Hadron Collider
measurements of the Standard Model Higgs mass, its partial widths of
and modes are discussed.Comment: 40 pages, 7 figures, version accepted in JHEP, relic density
discussion adde
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