Recently the PAMELA experiment has released its updated anti-proton flux and anti-proton to proton flux ratio data up to energies of ~200GeV. With no clear excess of cosmic ray anti-protons at high energies, one can extend constraints on the production of anti-protons from dark matter. In this letter, we consider both the cases of dark matter annihilating and decaying into standard model particles that produce significant numbers of anti-protons. We provide two sets of constraints on the annihilation cross-sections/decay lifetimes. In the one set of constraints we ignore any source of anti-protons other than dark matter, which give the highest allowed cross-sections/inverse lifetimes. In the other set we include also anti-protons produced in collisions of cosmic rays with interstellar medium nuclei, getting tighter but more realistic constraints on the annihilation cross-sections/decay lifetimes.
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.
PAMELA's observation that the cosmic ray positron fraction increases rapidly with energy implies the presence of primary sources of energetic electron-positron pairs. Of particular interest is the possibility that dark matter annihilations in the halo of the Milky Way provide this anomalous flux of antimatter. The recent measurement of the cosmic ray electron spectrum by the Fermi Gamma Ray Space Telescope, however, can be used to constrain the nature of any such dark matter particle. In particular, it has been argued that in order to accommodate the observations of Fermi and provide the PAMEL…
Measurements of the cosmic ray antiproton spectrum can be used to search for contributions from annihilating dark matter and to constrain the dark matter annihilation cross section. Depending on the assumptions made regarding cosmic ray propagation in the Galaxy, such constraints can be quite stringent. We revisit this topic, utilizing a set of propagation models fit to the cosmic ray boron, carbon, oxygen and beryllium data. We derive upper limits on the dark matter annihilation cross section and find that when the cosmic ray propagation parameters are treated as nuisance parameters (as we ar…
Recently reported tentative evidence for a gamma-ray line in the Fermi-LAT data is of great potential interest for identifying the nature of dark matter. We compare the implications for decaying and annihilating dark matter taking the constraints from continuum gamma-rays, antiproton flux and morphology of the excess into account. We find that higgsino and wino dark matter are excluded, also for nonthermal production. Generically, the continuum gamma-ray flux severely constrains annihilating dark matter. Consistency of decaying dark matter with the spatial distribution of the Fermi-LAT excess …
We consider the diffuse gamma ray data from FERMI first year observations and compare them to the gamma ray fluxes predicted by Dark Matter annihilation or decay (both from prompt emission and from Inverse Compton Scattering), for different observation regions of the sky and a range of Dark Matter masses, annihilation/decay channels and Dark Matter galactic profiles. We find that the data exclude large regions of the Dark Matter parameter space not constrained otherwise and discuss possible directions for future improvements. Also, we further constrain Dark Matter interpretations of the e+e- P…
We analyze the recently published Fermi-LAT diffuse gamma-ray measurements in the context of leptonically annihilating or decaying dark matter (DM) with the aim to explain simultaneously the isotropic diffuse gamma-ray and the PAMELA, Fermi and HESS (PFH) anomalous $e^\pm$ data. Five different DM annihilation/decay channels $2e$, $2μ$, $2τ$, $4e$, or $4μ$ (the latter two via an intermediate light particle $ϕ$) are generated with PYTHIA. We calculate both the Galactic and extragalactic prompt and inverse Compton (IC) contributions to the resulting gamma-ray spectra. To find the Galactic IC spec…
A long-lived decaying dark matter as a resolution to Fermi, PAMELA and ATIC anomalies is investigated in the framework of split supersymmetry (SUSY) without R-parity, where the neutralino is regarded as the dark matter and the extreme fine-tuned couplings for the long-lived neutralino are naturally evaded in the usual approach.
Dark matter (DM) annihilations have been widely studied as a possible explanation of excess gamma rays from the galactic center seen by Fermi/LAT. However most such models are in conflict with constraints from dwarf spheroidals. Motivated by this tension, we show that p-wave annihilating dark matter can easily accommodate both sets of observations due to the lower DM velocity dispersion in dwarf galaxies. Explaining the DM relic abundance is then challenging. We outline a scenario in which the usual thermal abundance is obtained through s-wave annihilations of a metastable particle, that event…
Motivated by the recent PAMELA and ATIC results, we calculate the electron and positron fluxes from the decay of lightest-superparticle (LSP) dark matter. We assume that the LSP is the dominant component of dark matter, and consider the case that the R-parity is very weakly violated so that the lifetime of the LSP becomes of the order of 10^26 sec. We will see that, with such a choice of the lifetime, the cosmic-ray electron and positron from the decay can be the source of the anomalous electron and positron fluxes observed by PAMELA and ATIC. We consider the possibilities that the LSP is the …
Recent measurements of cosmic-ray electron and positron fluxes by PAMELA and ATIC experiments may indicate the existence of annihilating dark matter with large annihilation cross section. We show that the dark matter annihilation in the big-bang nucleosynthesis epoch affects the light element abundances, and it gives stringent constraints on such annihilating dark matter scenarios for the case of hadronic annihilation. Constraints on leptonically annihilating dark matter models are less severer.
Dark matter decaying or annihilating into mu+mu- or tau+tau- has been proposed as an explanation for the e+e- anomalies reported by PAMELA and Fermi. Recent analyses show that IceCube, supplemented by DeepCore, will be able to significantly constrain the parameter space of decays to mu+mu-, and rule out decays to tau+tau- and annihilations to mu+mu- in less than five years of running. These analyses rely on measuring track-like events in IceCube+DeepCore from down-going nu_mu. In this paper we show that by instead measuring cascade events, which are induced by all neutrino flavors, IceCube+Dee…
In view of the IceCube's 6-year high-energy starting events (HESE) sample, we revisit the possibility that the updated data may be better explained by a combination of neutrino fluxes from dark matter decay and an isotropic astrophysical power-law than purely by the latter. We find that the combined two-component flux qualitatively improves the fit to the observed data over a purely astrophysical one, and discuss how these updated fits compare against a similar analysis done with the 4-year HESE data. We also update fits involving dark matter decay via multiple channels, without any contributi…
Much attention has been given to dark matter explanations of the PAMELA positron fraction and Fermi electronic excesses. For those theories with a TeV-scale WIMP annihilating through a light force-carrier, the associated Sommerfeld enhancement provides a natural explanation of the large boost factor needed to explain the signals, and the light force-carrier naturally gives rise to hard cosmic ray spectra without excess pi0 gamma rays or anti-protons. The Sommerfeld enhancement of the annihilation rate, which at low relative velocities v scales as 1/v, relies on the comparatively low velocity d…
High energy electrons and positrons from decaying dark matter can produce a significant flux of gamma rays by inverse Compton off low energy photons in the interstellar radiation field. This possibility is inevitably related with the dark matter interpretation of the observed PAMELA and FERMI excesses. The aim of this paper is providing a simple and universal method to constraint dark matter models which produce electrons and positrons in their decay by using the Fermi LAT gamma-ray observations in the energy range between 0.5 GeV and 300 GeV. We provide a set of universal response functions t…
Recently, a preliminary spectrum from the Fermi Gamma-ray Space Telescope has been presented for the inner galaxy (-30 < l < 30, -5 < b < 5), as well as the galactic center (-1 < l < 1, -1< b < 1). We consider the implications of these data for dark matter annihilation models, especially models capable of producing the cosmic-ray excesses previously observed by PAMELA and Fermi. These local cosmic-ray excesses, when extrapolated to the inner galaxy, imply inverse Compton scattering (ICS) gamma-ray signals largely consistent with the preliminary Fermi gamma-ray spectrum. For specific halos and …
Recently, the Fermi-LAT collaboration reported upper limits on the GeV gamma-ray flux from nearby clusters of galaxies. Motivated by these limits, we study corresponding constraints on gamma-ray emissions from two specific decaying dark matter models, one via grand unification scale suppressed operators and the other via R-parity violating operators. Both can account for the PAMELA and Fermi-LAT excesses of e^\pm. For GUT decaying dark matter, the gamma-rays from the M49 and Fornax clusters, with energy in the range of 1 to 10 GeV, lead to the most stringent constraints to date. As a result, t…
Fermi-LAT has confirmed the excess in cosmic positron fraction observed by PAMELA, which could be explained by dark matter annihilating or decaying in the center of the galaxy. Most existing models postulate that the dark matter annihilates or decays into final states with two or four leptons, which would produce diffuse gamma ray emissions that are in tension with data measured by Fermi-LAT. We point out that the tension could be alleviated if the dark matter decays into three-body final states with a pair of leptons and a missing particle. Using the goldstino decay in a certain class of supe…
Clear methods to differentiate between decaying and annihilating dark matter (DM) scenarios are still by and large unavailable. In this note, we study the potential astrophysical signatures of a new class of hidden sector decaying DM models, which can address the recent cosmic ray measurements. Such models may produce primary photons and/or neutrinos at large rates, correlated with the leptonic production. The photon and neutrino spectra will then contain sharp features at the TeV scale. We demonstrate the discovery potential for upcoming and future measurements by FERMI, HESS, AGIS and IceCub…
Satellite data is accumulating that suggests and constrains dark matter physics. We argue there is a very well motivated theoretical preexisting framework consistent with dark matter annihilation being observed by the PAMELA satellite detector. The dark matter is (mainly) the neutral W boson superpartner, the wino with mass below 200 GeV. Using the program GALPROP we study the annihilation products and backgrounds together. Antimatter and gammas from annihilating winos contribute below this energy. We explain why PAMELA data does not imply no antiproton signal was observed by PAMELA or earlier…
In this paper, we study the flux of electrons and positrons injected by pulsars and by annihilating or decaying dark matter in the context of recent ATIC, PAMELA, Fermi, and HESS data. We review the flux from a single pulsar and derive the flux from a distribution of pulsars. We point out that the particle acceleration in the pulsar magnetosphere is insufficient to explain the observed excess of electrons and positrons with energy E ~ 1 TeV and one has to take into account an additional acceleration of electrons at the termination shock between the pulsar and its wind nebula. We show that at e…
The evidence for dark matter particles, $χ$, is compelling based on Galactic to cosmological scale observations. Thus far, the promising weakly interacting massive particle scenario have eluded detection, motivating alternative models of dark matter. We consider scenarios involving superheavy dark matter (SHDM) that potentially can decay or annihilate to neutrinos and antineutrinos. In the mass range $m_χ=10^7-10^{15}\,{\rm GeV}$, we evaluate the sensitivities of future observatories POEMMA and GRAND for indirect dark matter detection via the measurement of neutrino-induced extensive air showe…
We study the local flux of electrons and positrons from annihilating Dark Matter (DM), and investigate how its spectrum depends on the choice of DM model and inhomogeneities in the DM distribution. Below a cutoff energy, the flux is expected to have a universal power-law form with an index n ~ -2. The cutoff energy and the behavior of the flux near the cutoff is model dependent. The dependence on the DM host halo profile may be significant at energies E < 100 GeV and leads to softening of the flux, n < -2. There may be additional features at high energies due to the presence of local clumps of…
Motivated by recent observations from Pamela, Fermi and H.E.S.S., we consider dark matter decays in the framework of supersymmetric SU(5) grand unification theories. An SU(5) singlet S is assumed to be the main component of dark matters, which decays into visible particles through dimension six operators suppressed by the grand unification scale. Under certain conditions, S decays dominantly into a pair of sleptons with universal coupling for all generations. Subsequently, electrons and positrons are produced from cascade decays of these sleptons. These cascade decay chains smooth the electron…
We show that, if decaying gravitino dark matter is responsible for the PAMELA and ATIC/PPB-BETS anomalies in the cosmic-ray electron and positron fluxes, both a reheating temperature and a gluino mass are constrained from above. In particular, the gluino mass is likely within the reach of LHC, if the observed baryon asymmetry is explained by thermal leptogenesis scenario.
We reconsider Sommerfeld-enhanced annihilation of dark matter (DM) into leptons to explain PAMELA and Fermi electron and positron observations, in light of possible new effects from substructure. There is strong tension between getting a large enough lepton signal while respecting constraints on the fluxes of associated gamma rays. We first show that these constraints become significantly more stringent than in previous studies when the contributions from background e^+ e^- are taken into account, so much so that even cored DM density profiles are ruled out. We then show how DM annihilations w…
The rise in the energy spectrum of the positron ratio, observed by the PAMELA satellite above 10 GeV, and other cosmic ray measurements, have been interpreted as a possible signature of Dark Matter annihilation in the Galaxy. However, the large number of free parameters, and the large astrophysical uncertainties, make it difficult to do conclusive statements about the viability of this scenario. Here, we perform a multi-wavelength, multi-messenger analysis, that combines in a consistent way the constraints arising from different astrophysical observations. We show that if standard assumptions …
We propose a new flavor model that can simlutaneously well-describe the indirect detection experiment of (decaying) dark matter in the cosmic-ray, with the binary icosahedral group A'_5. We show not only that the A'_{5} symmetry can derive quark and lepton masses and mixings consistently, but also that are expected some predictions for the lepton sector. And if we assume a gauge-singlet fermionic decaying dark matter, its decay operators are also constrained by this symmetry so that only dimension six operators of leptonic decay are allowed up to six dimensional Lagrangians. We find that the c…
In supersymmetric unified theories the dark matter particle can decay, just like the proton, through grand unified interactions with a lifetime of order of 10^{26} sec. Its decay products can be detected by several experiments -- including Fermi, HESS, PAMELA, ATIC, and IceCube -- opening our first direct window to physics at the TeV scale and simultaneously at the unification scale 10^{16} GeV. We consider possibilities for explaining the electron/positron spectra observed by HESS, PAMELA, and ATIC, and the resulting predictions for the gamma-ray, electron/positron, and neutrino spectra as wi…
We study a new flavor symmetric model with non-Abelian discrete symmetry T_{13}. The T_{13} group is isomorphic to Z_{13} \rtimes Z_3, and it is the minimal group having two complex triplets as the irreducible representations. We show that the T_{13} symmetry can derive lepton masses and mixings consistently. Moreover, if we assume a gauge-singlet fermionic decaying dark matter, its decay operators are also constrained by the T_{13} symmetry so that only dimension six operators of leptonic decay are allowed. We find that the cosmic-ray anomalies reported by PAMELA and Fermi-LAT are explained b…
The PAMELA, Fermi and HESS experiments (PFH) have shown anomalous excesses in the cosmic positron and electron fluxes. A very exciting possibility is that those excesses are due to annihilating dark matter (DM). In this paper we calculate constraints on leptonically annihilating DM using observational data on diffuse extragalactic gamma-ray background and measurements of the optical depth to the last-scattering surface, and compare those with the PFH favored region in the m_{DM} - <σ_A v> plane. Having specified the detailed form of the energy input with PYTHIA Monte Carlo tools we solve the r…
If dark matter decays into electrons and positrons, it can affect Galactic radio emissions and the local cosmic ray fluxes. We propose a new, more general analysis of constraints on dark matter. The constraints can be obtained for any decaying dark matter model by convolving the specific dark matter decay spectrum with a response function. We derive this response function from full-sky radio surveys at 408 MHz, 1.42 GHz and 23 GHz, as well as from the positron flux recently reported by PAMELA. We discuss the influence of astrophysical uncertainties on the response function, such as from propag…
It has recently been argued that the PAMELA, ATIC and PPB-BETS data showing an anomalous excess of high-energy cosmic ray positrons and electrons might be explained by dark matter annihilating in the Galactic halo with a cross section resonantly enhanced compared to its value in the primeval plasma. We find that with a very large annihilation cross section the flash of energetic photons and electron-positron pairs expected from dark-matter annihilation in the first protohalos that form at redshift z~40 is likely substantial and observable. As a consequence, bounds on the allowed energy injecti…
Decaying dark matter has previously been proposed as a possible explanation for the excess high energy cosmic ray electrons and positrons seen by PAMELA and the Fermi Gamma-Ray Space Telescope (FGST). To accommodate these signals however, the decays must be predominantly leptonic, to muons or taus, and therefore produce neutrinos, potentially detectable with the IceCube neutrino observatory. We find that, with five years of data, IceCube (supplemented by DeepCore) will be able to significantly constrain the relevant parameter space of decaying dark matter, and may even be capable of discoverin…
The PAMELA and ATIC collaborations have recently reported an excess in the cosmic ray positron and electron fluxes. These lepton anomalies might be related to cold dark matter (CDM) particles annihilating within a nearby dark matter clump. We outline regions of the parameter space for both the dark matter subhalo and particle model, where data from the different experiments are reproduced. We then confront this interpretation of the data with the results of the cosmological N-body simulation Via Lactea II. Having a sizable clump (Vmax = 9km/s) at a distance of only 1.2 kpc could explain the PA…
The recent PAMELA and ATIC/Fermi/HESS experiments have observed an excess of electrons and positrons, but not anti-protons, in the high energy cosmic rays. To explain this result, we construct a decaying hidden dark matter model in string theory compactification that incorporates the following two ingredients, the hidden dark matter scenario in warped compactification and the phenomenological proposal of hidden light particles that decay to the Standard Model. In this model, on higher dimensional warped branes, various warped Kaluza-Klein particles and the zero-mode of gauge field play roles o…
We derive robust model-independent bounds on DM annihilations and decays from the first year of FERMI gamma-ray observations of the whole sky. These bounds only have a mild dependence on the DM density profile and allow the following DM interpretations of the PAMELA and FERMI electron/positron excesses: primary channels mu+ mu-, mu+ mu-mu+mu- or e+ e- e+ e-. An isothermal-like density profile is needed for annihilating DM. In all such cases, FERMI gamma spectra must contain a significant DM component, that may be probed in the future.
While the excess in cosmic-ray electrons and positrons reported by PAMELA and Fermi may be explained by dark matter decaying primarily into charged leptons, this does not necessarily mean that dark matter should not have any hadronic decay modes. In order to quantify the allowed hadronic activities, we derive constraints on the decay rates of dark matter into WW, ZZ, hh, qqbar and gg using the Fermi and HESS gamma-ray data. We also derive gamma-ray constraints on the leptonic e+e-, mu+mu- and tau+tau- final states. We find that dark matter must decay primarily into mu+mu- or tau+tau- in order …
We analyze the impact of Fermi gamma-ray observations (primarily non-detections) of selected nearby galaxies, including dwarf spheroidals, and of clusters of galaxies on decaying dark matter models. We show that the fact that galaxy clusters do not shine in gamma rays puts the most stringent limits available to-date on the lifetime of dark matter particles for a wide range of particle masses and decay final states. In particular, our results put strong constraints on the possibility of ascribing to decaying dark matter both the increasing positron fraction reported by PAMELA and the high-energ…
We derive new bounds on decaying Dark Matter from the gamma ray measurements of (i) the isotropic residual (extragalactic) background by Fermi and (ii) the Fornax galaxy cluster by HESS. We find that those from (i) are among the most stringent constraints currently available, for a large range of DM masses and a variety of decay modes, excluding half-lives up to ~10^26 to few 10^27 seconds. In particular, they rule out the interpretation in terms of decaying DM of the e^\pm spectral features in Pamela, Fermi and HESS, unless very conservative choices are adopted. We also discuss future prospec…
The spectrum and morphology of gamma-rays from the Galactic Center and the spectrum of synchrotron emission observed from the Milky Way's radio filaments have each been interpreted as possible signals of $\sim$7-10 GeV dark matter particles annihilating in the Inner Galaxy. In dark matter models capable of producing these signals, the annihilations should also generate significant fluxes of $\sim$7-10 GeV positrons which can lead to a distinctive bump-like feature in local cosmic ray positron spectrum. In this letter, we show that while such a feature would be difficult to detect with PAMELA, …
New bounds on decaying Dark Matter are derived from the gamma-ray measurements of (i) the isotropic residual (extragalactic) background by Fermi and (ii) the Fornax galaxy cluster by H.E.S.S. We find that those from (i) are among the most stringent constraints currently available, for a large range of dark matter masses and a variety of decay modes, excluding half-lives up to about 10^26 to few 10^27 seconds. In particular, they rule out the interpretation in terms of decaying dark matter of the e+/- spectral features in PAMELA, Fermi and H.E.S.S., unless very conservative choices are adopted.…
We derive 95% CL lower limits on the lifetime of decaying dark matter in the channels $Zν$, $W\ell$ and $hν$ using measurements of the cosmic-ray antiproton flux by the PAMELA experiment. Performing a scan over the allowed range of cosmic-ray propagation parameters we find lifetime limits in the range of $8 \times 10^{28}$s to $5 \times 10^{25}$s for dark matter masses from roughly 100 GeV to 10 TeV. We apply these limits to the well-motivated case of gravitino dark matter in scenarios with bilinear violation of R-parity and find a similar range of lifetime limits for the same range of graviti…
We report on constraints on the lifetime of decaying gravitino dark matter in models with bilinear R-parity violation derived from observations of cosmic-ray antiprotons with the PAMELA experiment. Performing a scan over a viable set of cosmic-ray propagation parameters we find lower limits ranging from $8\times 10^{28}$s to $6\times 10^{28}$s for gravitino masses from roughly 100 GeV to 10 TeV. Comparing these limits to constraints derived from gamma-ray and neutrino observations we conclude that the presented antiproton limits are currently the strongest and most robust limits on the graviti…
We consider a new scenario for supersymmetric decaying dark matter without R-parity violation in theories with goldstini, which arise if supersymmetry is broken independently by multiple sequestered sectors. The uneaten goldstino naturally has a long lifetime and decays into three-body final states including the gravitino, which escapes detection, and two visible particles. The goldstini low-energy effective interactions are derived, which can be non-universal and allow the dark matter to be leptophilic, in contrast to the case of a single sector supersymmetry breaking. In addition, the three-…
Positron excess observed by PAMELA, Fermi and AMS02 may be due to dark matter (DM) pair annihilation or decay dominantly into muons. In this paper, we consider a scenario with thermal fermionic DM ($χ$) with mass $\sim O(1-2)$ TeV decaying into a dark Higgs ($ϕ$) and an active neutrino ($ν_a$) instead of the SM Higgs boson and $ν_a$. We first present a renormalizable model for this scenario with local dark $U(1)_X$ gauge symmetry, in which the DM $χ$ can be thermalized by Higgs portal and the gauge kinetic mixing. Assuming the dark Higgs ($ϕ$) mass is in the range $2 m_μ< m_ϕ< 2 m_{π^0}$, the …
We construct a Dark Matter (DM) annihilation module that can encompass the predictions from a wide array of models built to explain the recently reported PAMELA and ATIC/PPB-BETS excesses. We present a detailed analysis of the injection spectrums for DM annihilation and quantitatively demonstrate effects that have previously not been included from the particle physics perspective. With this module we demonstrate the parameter space that can account for the aforementioned excesses and be compatible with existing high energy gamma ray and neutrino experiments. However, we find that it is relativ…
We examine the constraints on final state radiation from Weakly Interacting Massive Particle (WIMP) dark matter candidates annihilating into various standard model final states, as imposed by the measurement of the isotropic diffuse gamma-ray background by the Large Area Telescope aboard the Fermi Gamma-Ray Space Telescope. The expected isotropic diffuse signal from dark matter annihilation has contributions from the local Milky Way (MW) as well as from extragalactic dark matter. The signal from the MW is very insensitive to the adopted dark matter profile of the halos, and dominates the signa…
Recent results from the PAMELA, ATIC, PPB BETS and Fermi collaborations extend the energy range in the electron flux measurement up to unexplored energies in the hundred GeVs range confirming the bump starting at about 10GeV already suggested by HEAT and AMS01 data . This bump can be explained by annihilating dark matter in the context of exotic physics, or by nearby astrophysical sources e.g. pulsars. In order to discriminate between competing models for primary positron production, the study of anisotropies ,complementary to the spectrum determination, shows up as new tool to look for the or…
The rise of the cosmic ray positron fraction with energy, as first observed with high confidence by PAMELA, implies that a large flux of high energy positrons has been recently (or is being currently) injected into the local volume of the Milky Way. With the new and much more precise measurement of the positron fraction recently provided by AMS, we revisit the question of the origin of these high energy positrons. We find that while some dark matter models (annihilating directly to electrons or muons) no longer appear to be capable of accommodating these data, other models in which ~1-3 TeV da…
We provide conservative bounds on the dark matter cross-section and lifetime from final state radiation produced by annihilation or decay into charged leptons, either directly or via an intermediate particle $ϕ$. Our analysis utilizes the experimental gamma-ray flux upper limits from four Milky Way dwarf satellites: HESS observations of Sagittarius and VERITAS observations of Draco, Ursa Minor, and Willman 1. Using 90% confidence level lower limits on the integrals over the dark matter distributions, we find that these constraints are largely unable to rule out dark matter annihilations or dec…
We perform a detailed examination of current constraints on annihilating and decaying dark matter models from both prompt and inverse-Compton emission photons, including both model-dependent and model-independent bounds. We also show that the observed isotropic diffuse gamma-ray background (DGRB), which provides one of the most conservative constraints on models of annihilating weak-scale dark matter particles, may enhance its sensitivity by a factor of ~2 to 3 (95% C.L.) as the Fermi-LAT experiment resolves DGRB contributing blazar sources with five years of observation. For our forecasts, we…
If interpreted in terms of decaying dark matter, the steep rise in the positron fraction of cosmic rays above 10 GeV, as observed by the PAMELA experiment, suggests an underlying production mechanism that favors leptonic channels. We consider a scenario where a portion of the dark matter is made of the gauginos of an unbroken hidden-sector U(1), which interact with the visible sector only through a tiny kinetic mixing. The second component of the dark matter is made of neutralinos, and depending on the mass spectrum, the lightest neutralino or the hidden gaugino becomes unstable and subject to…
The long standing anomaly in the positron flux as measured by the PAMELA and AMS-02 experiments could potentially be explained by dark matter (DM) annihilations. This scenario typically requires a large "boost factor" to be consistent with a thermal relic dark matter candidate produced via freeze-out. However, such an explanation is disfavored by constraints from CMB observations on energy deposition during the epoch of recombination. We discuss a scenario called late-decaying two-component dark matter (LD2DM), where the entire DM consists of two semi-degenerate species. Within this framework,…
The AMS experiment onboard the International Space Station has recently provided cosmic ray electron and positron data with unprecedented precision in the range from 0.5 to 350 GeV. The observed rise in the positron fraction at energies above 10 GeV remains unexplained, with proposed solutions ranging from local pulsars to TeV-scale dark matter. Here, we make use of this high quality data to place stringent limits on dark matter with masses below ~300 GeV, annihilating or decaying to leptonic final states, essentially independent of the origin of this rise. We significantly improve on existing…
In the light of the new IceCube data on the (yet unidentified) astrophysical neutrino flux in the PeV and sub-PeV range, we present an update on the status of decaying dark matter interpretation of the events. In particular, we develop further the angular distribution analysis and discuss the perspectives for diagnostics. By performing various statistical tests (maximum likelihood, Kolmogorov-Smirnov and Anderson-Darling tests) we conclude that currently the data show a mild preference (below the two sigma level) for the angular distribution expected from dark matter decay vs. the isotropic di…
The recent study on the the 6-year up-going muon neutrinos by the IceCube Collaboration support the hypothesis of a two-component scenario explaining the diffuse TeV-PeV neutrino flux. Once a hard astrophysical power-law is considered, an excess in the IceCube data is shown in the energy range 10-100 TeV (low-energy excess}). By means of a statistical analysis on the neutrino energy spectrum and on the angular distribution of neutrino arrival directions, we characterize a two-component neutrino flux where decaying/annihilating Dark Matter particles provide a contribution to the IceCube observa…
We study a two component dark matter candidate inspired by the Minimal Walking Technicolor model. Dark matter consists of a dominant SIMP-like dark atom component made of bound states between primordial helium nuclei and a doubly charged technilepton, and a small WIMP-like component made of another dark atom bound state between a doubly charged technibaryon and a technilepton. This scenario is consistent with direct search experimental findings because the dominant SIMP component interacts too strongly to reach the depths of current detectors with sufficient energy to recoil and the WIMP-like …
Annihilating dark matter (DM) models based on a scalar hidden sector with Higgs portal-like couplings to the Standard Model are considered as a possible explanation for recently observed cosmic ray excesses. Two versions of the model are studied, one with non-thermal DM as the origin of the boost factor and one with Sommerfeld enhancement. In the case of non-thermal DM, four hidden sector scalars which transform under a U(1)_{X} symmetry are added. The heaviest scalars decouple and later decay to DM scalars, so providing the boost factor necessary to explain the present DM annihilation rate. T…
We show that in F-theory GUTs, a natural explanation of flavor hierarchies in the quark and lepton sector requires a single point of E_8 enhancement in the internal geometry, from which all Yukawa couplings originate. The monodromy group acting on the seven-brane configuration plays a key role in this analysis. Moreover, the E_8 structure automatically leads to the existence of the additional fields and interactions needed for minimal gauge mediated supersymmetry breaking,__and almost nothing else__. Surprisingly, we find that in all but one Dirac neutrino scenario the messenger fields in the …
