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.

We extract at redshift z = 0 a Milky Way sized object including gas, stars and dark matter (DM) from a recent, high-resolution cosmological N-body simulation with baryons. Its resolution is sufficient to witness the formation of a rotating disk and bulge at the center of the halo potential, therefore providing a realistic description of the birth and the evolution of galactic structures in the ΛCDM cosmology paradigm. The phase-space structure of the central galaxy reveals that, throughout a thick region, the dark halo is co-rotating on average with the stellar disk. At the Earth's location, the rotating component, sometimes called dark disk in the literature, is characterized by a minimum lag velocity v lag 75 km/s, in which case it contributes to around 25% of the total DM local density, whose value is ρ DM 0.37 GeV/cm 3 . The velocity distributions also show strong deviations from pure Gaussian and Maxwellian distributions, with a sharper drop of the high velocity tail. We give a detailed study of the impact of these features on the predictions for DM signals in direct detection experiments. In particular, the question of whether the modulation signal observed by DAMA is or is not excluded by limits set by other experiments (CDMS, XENON and CRESST...) is re-analyzed and compared to the case of a standard Maxwellian halo. We consider spin-independent interactions for both the elastic and the inelastic scattering scenarios. For the first time, we calculate the allowed regions for DAMA and the exclusion limits of other null experiments directly from the velocity distributions found in the simulation. We then compare these results with the predictions of various analytical distributions. We find that the compatibility between DAMA and the other experiments is improved. In the elastic scenario, the DAMA modulation signal is slightly enhanced in the so-called channeling region, as a result of several effects that include a departure from a Maxwellian distribution and anisotropies in the velocity dispersions due to the dark disk. For the inelastic scenario, the improvement of the fit is mainly attributable to the departure from a Maxwellian distribution at high velocity. It is correctly modeled by a generalized Maxwellian distribution with a parameter α 1.95, or by a Tsallis distribution with q 0.75.

We introduce a new parametrization of the MNS lepton mixing matrix which separates the hierarchical Grand Unified relations among quarks and leptons. We argue that one large angle stems from the charged leptons, the other from the seesaw structure of the neutral lepton mass matrix. We show how two large mixing angles can arise naturally provided there are special requirements on the Dirac (∆I w = 1/2) and Majorana (∆I w = 0) masses. One possibility is a correlated hierarchy between them, the other is that the ∆I w = 0 Majorana mass has a specific texture; it is Dirac-like for two of the three families.

If dark matter (DM) simply consists in a scalar particle interacting dominantly with the Higgs boson, the ratio of its annihilation cross section -which is relevant both for the relic abundance and indirect detection-and its spin-independent scattering cross section on nuclei depends only on the DM mass. It is an intriguing result that, fixing the mass and direct detection rate to fit the annual modulation observed by the DAMA experiment, one obtains a relic density in perfect agreement with its observed value. In this short letter we update this result and confront the model to the recent CoGeNT data, tentatively interpreting the excess of events in the recoil energy spectrum as being due to DM. CoGeNT, as DAMA, points toward a light DM candidate, with somewhat different (but not necessarily incompatible) masses and cross sections. For the CoGeNT region too, we find an intriguing agreement between the scalar DM relic density and direct detection constraints. We also give the one σ region favoured by the CDMS-II events, that suggest a light DM candidate too, and the limits from Xenon10 2009 data, which, depending on the assumed scintillation efficiency, may exclude both CoGeNT and DAMA. Assuming CoGeNT and/or DAMA to be due to DM leads to definite predictions regarding indirect detection and Higgs search at the LHC.Recently, there has been some effervescence regarding what may be first hints of direct detection of dark matter (DM) from the galactic halo. The most recent is related to the CoGeNT experiment, a low background germanium crystal based detector, with a rather modest exposure time and detector mass, but very low threshold energy, which has announced an anomaly in the form of an excess of events at low recoil energies [1]. Although the collaboration clearly leans toward natural radioactivity as the cause for the observed excess, they do put forward the possibility that the events may be explained by the elastic collisions of DM from the galactic halo, with a mass in the ∼ 7 − 10 GeV range, and a rather large spin independent (SI) cross section on nuclei, σ SI ∼ 7 × 10 −41 cm 2 . Surprizingly, these values for the mass and scattering cross section are not too different from those required to fit the DAMA/Libra and DAMA/NaI (DAMA in the sequel) events. DAMA has observed 11 successive cycles of annual modulation in the rate of nuclear recoils, with a statistical significance of 8.2σ [2]. These measurements are consistent with the signal that would arise from elastic scattering of a WIMP from the galactic halo with the nuclei in the detectors, the flux of DM particles being modulated by the periodic motion of the Earth around the Sun [3,4].There has been much work on the DM interpretation of the recent DAMA data (see e.g. [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]). In [21] (see also [22]), it has been shown that the DAMA results may be explained as being caused by the elastic scattering of a singlet scalar DM candidate interacting through the Higgs portal. This particle may be a true singl...