Scalar Multiplet Dark Matter

We perform a systematic study of the phenomenology associated to models where the dark matter consists in the neutral component of a scalar SU(2)_L n-uplet, up to n=7. If one includes only the pure gauge induced annihilation cross-sections it is known that such particles provide good dark matter candidates, leading to the observed dark matter relic abundance for a particular value of their mass around the TeV scale. We show that these values actually become ranges of values -which we determine- if one takes into account the annihilations induced by the various scalar couplings appearing in these models. This leads to predictions for both direct and indirect detection signatures as a function of the dark matter mass within these ranges. Both can be largely enhanced by the quartic coupling contributions. We also explain how, if one adds right-handed neutrinos to the scalar doublet case, the results of this analysis allow to have altogether a viable dark matter candidate, successful generation of neutrino masses, and leptogenesis in a particularly minimal way with all new physics at the TeV scale.Comment: 43 pages, 20 figure

Positrons and antiprotons from inert doublet model dark matter

In the framework of the Inert Doublet Model, a very simple extension of the Standard Model, we study the production and propagation of antimatter in cosmic rays coming from annihilation of a scalar dark matter particle. We consider three benchmark candidates, all consistent with the WMAP cosmic abundance and existing direct detection experiments, and confront the predictions of the model with the recent PAMELA, ATIC and HESS data. For a light candidate, M_{DM} = 10 GeV, we argue that the positron and anti-proton fluxes may be large, but still consistent with expected backgrounds, unless there is an enhancement (boost factor) in the local density of dark matter. There is also a substantial anti-deuteron flux which might be observable by future experiments. For a candidate with M_{DM} = 70 GeV, the contribution to positron and anti-proton fluxes is much smaller than the expected backgrounds. Even if a boost factor is invoked to enhance the signals, the candidate is unable to explain the observed positron and anti-proton excesses. Finally, for a heavy candidate, M_{DM} = 10 TeV, it is possible to fit the PAMELA excess (but, unfortunately, not the ATIC one) provided there is a large enhancement, either in the local density of dark matter or through the Sommerfeld effect.Comment: 17 pages ; v2: matches JCAP published versio

High Energy Cosmic Rays from Decaying Supersymmetric Dark Matter

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 gravitino, the lightest neutralino, and scalar neutrino, and discuss how the resultant fluxes depend on the dark-matter model. We also discuss the fluxes of gamma-ray and anti-proton, and show that those fluxes can be consistent with the observed value in the parameter region where the PAMELA and ATIC anomalies are explained.Comment: 34 pages, 20 figures, published versio

Charge Asymmetric Cosmic Rays as a probe of Flavor Violating Asymmetric Dark Matter

The recently introduced cosmic sum rules combine the data from PAMELA and Fermi-LAT cosmic ray experiments in a way that permits to neatly investigate whether the experimentally observed lepton excesses violate charge symmetry. One can in a simple way determine universal properties of the unknown component of the cosmic rays. Here we attribute a potential charge asymmetry to the dark sector. In particular we provide models of asymmetric dark matter able to produce charge asymmetric cosmic rays. We consider spin zero, spin one and spin one-half decaying dark matter candidates. We show that lepton flavor violation and asymmetric dark matter are both required to have a charge asymmetry in the cosmic ray lepton excesses. Therefore, an experimental evidence of charge asymmetry in the cosmic ray lepton excesses implies that dark matter is asymmetric.Comment: 12 pages, 8 figures. Revised version to match the published versio

Dark matter and collider phenomenology of split-UED

We explicitly show that split-universal extra dimension (split-UED), a recently suggested extension of universal extra dimension (UED) model, can nicely explain recent anomalies in cosmic-ray positrons and electrons observed by PAMELA and ATIC/PPB-BETS. Kaluza-Klein (KK) dark matters mainly annihilate into leptons because the hadronic branching fraction is highly suppressed by large KK quark masses and the antiproton flux agrees very well with the observation where no excess is found . The flux of cosmic gamma-rays from pion decay is also highly suppressed and hardly detected in low energy region (E<20 GeV). Collider signatures of colored KK particles at the LHC, especially q_1 q_1 production, are studied in detail. Due to the large split in masses of KK quarks and other particles, hard p_T jets and missing E_T are generated, which make it possible to suppress the standard model background and discover the signals.Comment: 32 pages, 15 figure

The cosmic ray positron to electron ratio in the energy range 0.85 to 14 GEV

Consiglio Nazionale delle Ricerche (CNR). Biblioteca Centrale / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

The cosmic ray antiproton flux between 0.62 and 3.19 GeV measured near solar minimum

Biblioteca Centrale CNR / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

Probing Gravitino Dark Matter with PAMELA and Fermi

We analyze the cosmic-ray signatures of decaying gravitino dark matter in a model independent way based on an operator analysis. Thermal leptogenesis and universal boundary conditions at the GUT scale restrict the gravitino mass to be below 600 GeV. Electron and positron fluxes from gravitino decays, together with the standard GALPROP background, cannot explain both, the PAMELA positron fraction and the electron + positron flux recently measured by Fermi LAT. For gravitino dark matter, the observed fluxes require astrophysical sources. The measured antiproton flux allows for a sizable contribution of decaying gravitinos to the gamma-ray spectrum, in particular a line at an energy below 300 GeV. Future measurements of the gamma-ray flux will provide important constraints on possible signatures of decaying gravitino dark matter at the LHC.Comment: 21 pages, 6 figures. v3: published versio

Decaying dark matter in light of the PAMELA and Fermi LAT data

A series of experiments measuring high-energy cosmic rays have recently reported strong indications for the existence of an excess of high-energy electrons and positrons. If interpreted in terms of the decay of dark matter particles, the PAMELA measurements of the positron fraction and the Fermi LAT measurements of the total electron-plus-positron flux restrict the possible decaying dark matter scenarios to a few cases. Analyzing different decay channels in a model-independent manner, and adopting a conventional diffusive reacceleration model for the background fluxes of electrons and positrons, we identify some promising scenarios of dark matter decay and calculate the predictions for the diffuse extragalactic gamma-ray flux, including the contributions from inverse Compton scattering with the interstellar radiation field.Comment: 27 pages, 14 figures - Version accepted for publication in JCAP. Clarifications added on the underlying astrophysical assumptions. Fig. 4 and 9 adde