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Browsing by Author "Ullio, Piero"

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Browsing by Author "Ullio, Piero"

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  • Accurate estimate of the relic density and the kinetic decoupling in non-thermal dark matter models
    Arcadi, Giorgio; Ullio, Piero (American Physical Society, 2011-08-12)
    Non-thermal dark matter generation is an appealing alternative to the standard paradigm of thermal WIMP dark matter. We reconsider non-thermal production mechanisms in a systematic way, and develop a numerical code ...
  • Antiprotons from dark matter annihilation in the Galaxy: Astrophysical uncertainties
    Evoli, Carmelo; Cholis, Ilias; Grasso, Dario; Maccione, Luca; Ullio, Piero (American Physical Society, 2012-06-07)
    The latest years have seen steady progresses in WIMP dark matter (DM) searches, with hints of possible signals suggested by both direct and indirect detection experiments. Antiprotons can play a key role validating ...
  • Aspects of production and kinetic decoupling of non-thermal dark matter
    Arcadi, Giorgio; Ullio, Piero (IOP Publishing, 2011-11-28)
    We reconsider non-thermal production of WIMP dark matter in a systematic way and using a numerical code for accurate computations of dark matter relic densities. Candidates with large pair annihilation rates are favored, ...
  • Aspects of Wimp Dark Matter: Multi-wavelength signals and Extra-dimensions scenarios
    Regis, Marco (SISSA, 2008-10-15)
    Weakly interacting massive particles (WIMPs) are among the leading candidates for the dark matter (DM) component in the Universe. The thesis presents a review of the current status of the DM problem, focussing on the WIMP ...
  • Cosmological dark matter annihilations into gamma-rays: a closer look
    Ullio, Piero; Bergstrom, Lars; Edsjo, Joakim; Lacey, Cedric (American Physical Society, 2002)
    We investigate the prospects of detecting weakly interacting massive particle (WIMP) dark matter by measuring the contribution to the extragalactic gamma-ray radiation induced, in any dark matter halo and at all redshifts, ...
  • A Dark Matter Candidate from an Extra (Non-Universal) Dimension
    Regis, Marco; Serone, Marco; Ullio, Piero (2007-01-31)
    We show that a recently constructed five-dimensional (5D) model with gauge-Higgs unification and explicit Lorentz symmetry breaking in the bulk, provides a natural dark matter candidate. This is the lightest Kaluza-Klein ...
  • Dark matter from late decays and the small-scale structure problems
    Borzumati, Francesca; Bringmann, Torsten; Ullio, Piero (2008-04-22)
    The generation of dark matter in late decays of quasi-stable massive particles has been proposed as a viable framework to address the excess of power found in numerical N-body simulations for cold dark matter cosmologies. ...
  • Dark Matter in split extended supersymmetry
    Provenza, Alessio; Quiros, Mariano; Ullio, Piero (2006-09-07)
    We consider the split extended (N=2) supersymmetry scenario recently proposed by Antoniadis et al. [hep-ph/0507192] as a realistic low energy framework arising from intersecting brane models. While all scalar superpartners ...
  • Dark-matter spike at the galactic center?
    Ullio, Piero; HongSheng Zhao; Kamionkowski, Marc (American Physical Society, 2001)
    The past growth of the central black hole (BH) might have enhanced the density of cold dark matter halo particles at the Galactic center. We compute this effect in realistic growth models of the present (2-3)*10**6 solar ...
  • DarkSUSY: computing supersymmetric dark matter properties numerically
    Gondolo, P.; Edsjo, Joakim; Ullio, Piero; Bergstrom, Lars; Schelke, Mia; Baltz, Edward A. (IOP Publishing, 2004-07-14)
    The question of the nature of the dark matter in the Universe remains one of the most outstanding unsolved problems in basic science. One of the best motivated particle physics candidates is the lightest supersymmetric ...
  • Detecting dark matter WIMPs in the Draco dwarf: A multiwavelength perspective
    Colafrancesco, Sergio; Profumo, Stefano; Ullio, Piero (2007-09-03)
    We explore the possible signatures of dark matter pair annihilations in the nearby dwarf spheroidal galaxy Draco. After investigating the mass models for Draco in the light of available observational data, we carefully ...
  • Diffuse galactic gamma rays at intermediate and high latitudes. I. Constraints on the ISM properties
    Cholis, Ilias; Tavakoli, Maryam; Evoli, Carmelo; Maccione, Luca; Ullio, Piero (IOP Publishing, 2012-05-03)
    We study the high latitude (|b|>10) diffuse gamma-ray emission in the Galaxy in light of the recently published data from the Fermi collaboration at energies between 100 MeV and 100 GeV. The unprecedented accuracy in ...
  • Direct probes of dark matter in the cluster 1ES0657-556 through microwave observations
    Colafrancesco, Sergio; de Bernardis, Paolo; Masi, S.; Polenta, G.; Ullio, Piero (2007-09-03)
    The cluster 1ES0657-556 is an ideal astrophysical laboratory to study the distribution and the nature of Dark Matter because this last component is spatially separated from the intracluster gas. We show that microwave ...
  • Direct versus indirect detection in mSUGRA with self-consistent halo models
    Edsjo, Joakim; Schelke, Mia; Ullio, Piero (IOP Publishing, 2004-09-10)
    We perform a detailed analysis of the detection prospects of neutralino dark matter in the mSUGRA framework. We focus on models with a thermal relic density, estimated with high accuracy using the DarkSUSY package, in ...
  • Electroweak Baryogenesis, Large Yukawas and Dark Matter
    Provenza, Alessio; Quiros, Mariano; Ullio, Piero (2006-02-17)
    It has recently been shown that the electroweak baryogenesis mechanism is feasible in Standard Model extensions containing extra fermions with large Yukawa couplings. We show here that the lightest of these fermionic fields ...
  • The Galactic center as a dark matter gamma-ray source
    Cesarini, Alessandro; Fucito, Francesco; Lionetto, Andrea; Morselli, Aldo; Ullio, Piero (Elsevier, 2004-06)
    The EGRET telescope has identified a gamma-ray source at the Galactic center. We point out here that the spectral features of this source are compatible with the gamma-ray flux induced by pair annihilations of dark matter ...
  • Indirect detection of neutralino dark matter candidates in anomaly-mediated supersymmetry breaking scenarios
    Ullio, Piero (IOP Publishing, 2001)
    We consider a model for neutralino dark matter candidates arising in anomaly-mediated supersymmetry breaking schemes, and examine its testability through the search for exotic cosmic rays produced by neutralino pair ...
  • Just so Higgs boson
    Bazzocchi, Federica; Fabbrichesi, Marco; Ullio, Piero (2007-09-03)
    We discuss a minimal extension to the standard model in which there are two Higgs bosons and, in addition to the usual fermion content, two fermion doublets and one fermion singlet. The little hierachy problem is solved ...
  • The local dark matter phase-space density and impact on WIMP direct detection
    Catena, Riccardo; Ullio, Piero (IOP Publishing, 2012-05-03)
    We present a new determination of the local dark matter phase-space density. This result is obtained implementing, in the limit of isotropic velocity distribution and spherical symmetry, Eddington's inversion formula, ...
  • Loop and non-perturbative e ects in the dark matter phenomenology
    Hryczuk, Andrzej (SISSA, 2012-09-24)
    In this thesis we analyze the importance of the one-loop corrections and the non-perturbative Sommerfeld enhancement on the dark matter thermal relic density and indirect detection signals. We discuss general properties of ...