90 research outputs found
Inverse Problem of Cosmic-Ray Electron/Positron from Dark Matter
We discuss the possibility of solving the inverse problem of the cosmic-ray
electron/positron from decaying/annihilating dark matter, and show simple
analytic formulae to reconstruct the source spectrum of the electron/positron
from the observed flux. We also illustrate our approach by applying the
obtained formula to the just released Fermi data as well as the new HESS data.Comment: 16 pages, 6 figure
Parameters in a Class of Leptophilic Dark Matter Models from PAMELA, ATIC and FERMI
In this work we study a class of leptophilic dark matter models, where the
dark matter interacts with the standard model particles via the
gauge boson, to explain the excess in cosmic rays
observed by ATIC and PAMELA experiments, and more recently by Fermi experiment.
There are three types of models: a) , b)
, and c) . Although ATIC or Fermi
data is consistent with PAMELA data separately, ATIC and Fermi data do not
agree with each other. We therefore aim to identify which of the three models
can explain which data set better. We find that models a) and b) can give
correct dark matter relic density and explain the ATIC and PAMELA data
simultaneously recur to the Breit-Wigner enhancement. Whereas model c) with a
larger mass can explain Fermi and PAMELA data simultaneously. In all
cases the model parameters are restricted to narrow regions. Future improved
data will decide which set of data are correct and also help to decide the
correct dark matter model.Comment: Latex 15 pages with 5 figures. Modified to include discussions of
recent Fermi data on the leptophilic models studied in this paper. Title also
modifie
Dark Matter: The Leptonic Connection
Recent observatons of high-energy positrons and electrons by the PAMELA and
ATIC experiments may be an indication of the annihilation of dark matter into
leptons and not quarks. This leptonic connection was foreseen already some
years ago in two different models of radiative neutrino mass. We discuss here
the generic interactions (nu eta^0 - l eta^+) chi and l^c zeta^- chi^c which
allow this to happen, where chi and/or chi^c are fermionic dark-matter
candidates. We point out in particular the importance of chi chi to l^+ l^-
gamma to both positron and gamma-ray signals within this framework.Comment: 4 pages, 5 figures. v2: PLB versio
Detecting the dark matter annihilation at the ground EAS detectors
In this paper we study the possibility of detecting gamma rays from dark
matter annihilation in the subhalos of the Milky Way by the ground based EAS
detectors within the frame of the minimal supersymmetric standard model. Based
on the Monte Carlo simulation we also study the properties of two specific EAS
detectors, the ARGO and HAWC, and the sensitivities of these detectors on the
detection of dark matter annihilation. We find the ground EAS detectors have
the possibility to observe such signals. Conversely if no signal observed we
give the constraints on the supersymmetric parameter space, which however
depends on the subhalos properties.Comment: 23 pages, 9 figures, accepted by NP
Absolute electron and positron fluxes from PAMELA/Fermi and Dark Matter
We extract the positron and electron fluxes in the energy range 10 - 100 GeV
by combining the recent data from PAMELA and Fermi LAT. The {\it absolute
positron and electron} fluxes thus obtained are found to obey the power laws:
and respectively, which can be confirmed by the
upcoming data from PAMELA. The positron flux appears to indicate an excess at
energies E\gsim 50 GeV even if the uncertainty in the secondary positron flux
is added to the Galactic positron background. This leaves enough motivation for
considering new physics, such as annihilation or decay of dark matter, as the
origin of positron excess in the cosmic rays.Comment: Accepted by JCA
Power Spectra in Spacetime Noncommutative Inflation
String/M theory inspires an uncertainty relation between space and time which
deviates from general relativity. It is possible to explore this deviation from
cosmological observations, in particular from the CMB fluctuation spectrum.
This paper extends some previous observations to more general inflation
schemes, we find that the noncommutative spacetime effects always suppress the
power spectrum, of both the scalar and tensor perturbations, and may provide a
large enough running of the spectral index to fit the WMAP data in the
inflation model.Comment: 19 pages, 6 figures, harvmac; 2 references added; only references
added; Accepted for publication in Nucl. Phys.
R-Parity Breaking via Type II Seesaw, Decaying Gravitino Dark Matter and PAMELA Positron Excess
We propose a new class of R-parity violating extension of MSSM with type II
seesaw mechanism for neutrino masses where an unstable gravitino is the dark
matter of the Universe. It decays predominantly into three leptons final
states, thereby providing a natural explanation of the positron excess but no
antiproton excess in the PAMELA experiment. The model can explain neutrino
masses without invoking any high scale physics while keeping the pre-existing
baryon asymmetry of the universe in tact.Comment: 13 pages, 6 figures; accepted for publication in PL
The Leptonic Higgs as a Messenger of Dark Matter
We propose that the leptonic cosmic ray signals seen by PAMELA and ATIC
result from the annihilation or decay of dark matter particles via states of a
leptonic Higgs doublet to leptons, linking cosmic ray signals of dark
matter to LHC signals of the Higgs sector. The states of the leptonic Higgs
doublet are lighter than about 200 GeV, yielding large and
event rates at the LHC. Simple models are
given for the dark matter particle and its interactions with the leptonic
Higgs, for cosmic ray signals arising from both annihilations and decays in the
galactic halo. For the case of annihilations, cosmic photon and neutrino
signals are on the verge of discovery.Comment: 34 pages, 9 figures, minor typos corrected, references adde
Double-action dark matter, PAMELA and ATIC
Motivated by a two-bump (or 1-peak plus 1-hump) structure in the ATIC data,
we perform a statistical analysis fitting the PAMELA and ATIC data to a dark
matter model, in which the dark matter particle can undergo both annihilation
and decay. Using a chi-square analysis we show that both data can be
simultaneously fitted better with such a double-action dark matter particle. We
use an existing neutrino mass model in literature to illustrate the idea.Comment: RevTex 18 pages, 4 figures; version 2: references corrected, an
estimate modified; version 3, a new figure on annihilation, more discussion
and reference
Detecting light leptophilic gauge boson at BESIII detector
The extra gauge boson named U-boson, has been proposed to
mediate the interaction among leptons and dark matter (DM), in order to account
for the observations by PAMELA and ATIC. In such kind of models, the extra U(1)
gauge group can be chosen as with the th generation
lepton number. This anomaly-free model provides appropriate dark matter relic
density and boost factor required by experiments. In this work the
observability of such kind of U-boson at BESIII detector is investigated
through the processes , followed by ,
and . In the invisible channel where
U-boson decays into neutrinos, BESIII can measure the coupling of the extra down to because of the low Standard Model
backgrounds. In the visible channel where U-boson decays into charged lepton
pair, BESIII can only measure the coupling down to due to the large irreducible QED backgrounds.Comment: 7pages, 9figures; V2: SecIII corrected, discussions adde
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