Cosmic-ray nuclei Ñuxes are expected to be measured with high precision in the near future. For instance, high-quality data on the antiproton component could give important clues about the nature of the astronomical dark matter. A very good understanding of the di †erent aspects of cosmic-ray propagation is therefore necessary. In this paper, we use cosmic-ray nuclei data to give constraints on the di †u-sion parameters. Propagation is studied with semianalytical solutions of a di †usion model, and we give new analytical solutions for radioactively produced species. Our model includes convection and reacceleration, as well as the standard energy losses. We perform a s2 analysis over B/C data for a large number of conÐgurations obtained by varying the relevant parameters of the di †usion model. A very good agreement with B/C data arises for a number of conÐgurations, all of which are compatible with sub-Fe/Fe data. Di †erent source spectra Q(E) and di †usion coefficients K(E) have been tried, but for both parameters only one form gives a good Ðt. Another important result is that models without convection or without reacceleration are excluded. We Ðnd that the various parameters, i.e., the di †usion coefficient normalization and spectral index d, the halo thickness L , the velocity and the K 0 Alfven V A , convection velocity are strongly correlated. We obtain limits on the spectral index d of the di †usion V c coefficient, and in particular we exclude a Kolmogorov spectrum (d \ 13 ).

We calculate the antiproton flux due to relic neutralino annihilations, in a two-dimensional diffusion model compatible with stable and radioactive cosmic ray nuclei. We find that the uncertainty in the primary flux induced by the propagation parameters alone is about two orders of magnitude at low energies, and it is mainly determined by the lack of knowledge on the thickness of the diffusive halo. On the contrary, different dark matter density profiles do not significantly alter the flux: a NFW distribution produces fluxes which are at most 20% higher than an isothermal sphere. The most conservative choice for propagation parameters and dark matter distribution normalization, together with current data on cosmic antiprotons, cannot lead to any definitive constraint on the supersymmetric parameter space, neither in a low-energy effective MSSM, or in a minimal SUGRA scheme. However, if the best choice for propagation parameters -corresponding to a diffusive halo of L = 4 kpc -is adopted, some supersymmetric configurations with the neutralino mass mχ < ∼ 100 GeV should be considered as excluded. An enhancement flux factor -due for instance to a clumpy dark halo or to a higher local dark matter density -would imply a more severe cut on the supersymmetric parameters.PACS numbers: 95.35.+d,98.35.Gi,98.35.Pr,98.70.Sa,11.30.Pb,12.60.Jv,95.30.Cq

We confirm and extend the recent finding that the central surface density r_0*rho_0 galaxy dark matter halos, where r_0 and rho_0 are the halo core radius and central density, is nearly constant and independent of galaxy luminosity. Based on the co-added rotation curves of about 1000 spiral galaxies, mass models of individual dwarf irregular and spiral galaxies of late and early types with high-quality rotation curves and, galaxy-galaxy weak lensing signals from a sample of spiral and elliptical galaxies, we find that log(r_0*rho_0) = 2.15 +- 0.2, in units of log(Msol/pc^2). We also show that the observed kinematics of Local Group dwarf spheroidal galaxies are consistent with this value. Our results are obtained for galactic systems spanning over 14 magnitudes, belonging to different Hubble Types, and whose mass profiles have been determined by several independent methods. In the same objects, the approximate constancy of rho_0*r_0 is in sharp contrast to the systematical variations, by several orders of magnitude, of galaxy properties, including rho_0 and central stellar surface density.Comment: Accepted for publication in MNRAS. 9 pages, 4 figure

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Once the energy spectrum of the secondary component is well understood, measurements of the antiproton cosmic-ray flux at the Earth will be a powerful way to indirectly probe for the existence of supersymmetric relics in the galactic halo. Unfortunately, it is still spoilt by considerable theoretical uncertainties. As shown in this work, searches for low-energy antideuterons appear in the mean time as a plausible alternative, worth being explored. Above a few GeV/n, a dozen spallation antideuterons should be collected by the future AMS experiment on board ISSA. For energies less than ∼ 3 GeV/n, theD spallation component becomes negligible and may be supplanted by a potential supersymmetric signal. If a few low-energy antideuterons are discovered, this should be seriously taken as a clue for the existence of massive neutralinos in the Milky Way.

The predictions of our previous analysis about possible low-mass (mχ < ∼ 50 GeV) relic neutralinos are discussed in the light of some recent results from WIMP direct detection experiments. It is proved that these light neutralinos are quite compatible with the new annual-modulation data of the DAMA Collaboration; our theoretical predictions are also compared with the upper bounds of the CDMS and EDELWEISS Collaborations.PACS numbers: 95.35.+d,11.30.Pb,12.60.Jv,95.30.Cq Searches for neutralinos at colliders have not yet reached the sensitivity required to place a direct lower bound on the neutralino mass m χ . The commonly quoted and employed bound m χ > ∼ 50 GeV is derived from the lower bound on the chargino mass determined at LEP2 (m ± χ > ∼ 100 GeV) under the assumption that the U (1) and SU (2) gaugino masses M 1 and M 2 satisfy the standard relationship M 1 ≃ 1 2 M 2 at the electroweak scale. This hypothesis is a consequence of the assumption that these mass parameters have a common value at the grand unification (GUT) scale.In supersymmetric models with R-parity conservation and no gaugino-unification assumption at the GUT scale, an absolute lower limit on m χ cannot be derived from the lower bound on the chargino mass. Instead, it may be established by applying the upper bound on the Cold Dark Matter (CDM) content in the Universe, Ω CDM ≡ ρ CDM /ρ c , in combination with constraints imposed on the Higgs and supersymmetric parameters by measurements at colliders and other precision experiments (muon g − 2, BR(b → s + γ)). This point was discussed in Refs. [1,2], where a lower bound on the neutralino mass of about 6 GeV was established as a consequence of the recent 2σ C.L. (2) is a consequence the fact that the detection rate has a lower bound induced by the upper limit on Ω CDM h 2 .Recalling that, for neutralino-matter interactions, coherent effects systematically dominate over spindependent ones, the aforementioned properties (1)-(2) are conveniently displayed in terms of the quantity ξσ is the neutralino-nucleon scalar cross-section and ξ is a rescaling factor between the neutralino local matter density ρ χ and the total local dark matter density ρ 0 : ξ ≡ ρ χ /ρ 0 . Following a standard assumption, ξ may be taken asThe supersymmetric model considered in the present paper is an effMSSM scheme at the electroweak scale, with the following independent parameters: M 2 , µ, tan β, m A , mq, ml, A and R ≡ M 1 /M 2 . Notations are as follows: tan β the ratio of the two Higgs v.e.v.'s: tan β ≡< H 0 2 >/< H 0 1 >, µ is the Higgs mixing mass parameter, m A the mass of the CP-odd neutral Higgs boson, mq is a soft-mass common to all squarks, ml is a soft-mass common to all sleptons, A is a common dimensionless trilinear parameter for the third family, Ab = At ≡ Amq and Aτ ≡ Aml (the trilinear parameters for the other families being set equal to zero). Since we are here interested in light neutralinos, we consider values of R lower than its standard value: R GUT ≃ 0.5; for definiteness, we take R in the range: ...

Context. The so-called excess of cosmic ray (CR) positrons observed by the PAMELA satellite up to 100 GeV has led to many interpretation attempts, from standard astrophysics to a possible exotic contribution from dark matter annihilation or decay. The Fermi data subsequently obtained about CR electrons and positrons in the range 0.02-1 TeV, and HESS data above 1 TeV have provided additional information about the leptonic content of local Galactic CRs. Aims. We analyse predictions of the CR lepton fluxes at the Earth of both secondary and primary origins, evaluate the theoretical uncertainties, and determine their level of consistency with respect to the available data. Methods. For propagation, we use a relativistic treatment of the energy losses for which we provide useful parameterizations. We compute the secondary components by improving on the method that we derived earlier for positrons. For primaries, we estimate the contributions from astrophysical sources (supernova remnants and pulsars) by considering all known local objects within 2 kpc and a smooth distribution beyond. Results. We find that the electron flux in the energy range 5-30 GeV is well reproduced by a smooth distant distribution of sources with index γ ∼ 2.3−2.4, while local sources dominate the flux at higher energy. For positrons, local pulsars have an important effect above 5-10 GeV. Uncertainties affecting the source modeling and propagation are degenerate and each translates into about one order of magnitude error in terms of local flux. The spectral shape at high energy is weakly correlated with the spectral indices of local sources, but more strongly with the hierarchy in their distance, age and power. Despite the large theoretical errors that we describe, our global and self-consistent analysis can explain all available data without over-tuning the parameters, and therefore without the need to consider any exotic physics. Conclusions. Though a standard paradigm of Galactic CRs is well established, our results show that we can hardly talk about any standard model of CR leptons, because of the very large theoretical uncertainties. Our analysis provides details about the impact of these uncertainties, thereby sketching a roadmap for future improvements.

Indirect detection signals from dark matter annihilation are studied in the positron channel. We discuss in detail the positron propagation inside the galactic medium: we present novel solutions of the diffusion and propagation equations and we focus on the determination of the astrophysical uncertainties which affect the positron dark matter signal. We find dark matter scenarios and propagation models that nicely fit existing data on the positron fraction. Finally, we present predictions both on the positron fraction and on the flux for already running or planned space experiments, concluding that they have the potential to discriminate a possible signal from the background and, in some cases, to distinguish among different astrophysical propagation models. PACS numbers: 95.35.+d,98.35.Gi,11.30.Pb,95.30.Cq