6,454 research outputs found

    Cold Dark Matter and Neutralinos

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    Neutralinos are natural candidates for cold dark matter in many realizations of supersymmetry. We briefly review our recent results in the evaluation of neutralino relic abundance and direct detection rates in a class of supergravity models.Comment: 4 pages, 4 figures, uses espcrc2.sty. Proc. of "Sources and detection of dark matter and dark energy in the Universe (DM2002)". The version on the archive has low-resolution figures. The paper with high-resolution figures can be found at http://www.to.infn.it/~fornengo/proceedings/marinadelrey02.ps.gz or through http://www.to.infn.it/astropart

    Upper bounds on signals due to WIMP self--annihilation: comments on the case of the synchrotron radiation from the galactic center and the WMAP haze

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    Two recent papers reconsider the possibility that the excess of microwave emission from a region within ∌200\sim 20^0 of the galactic center (the {\it WMAP haze}), measured by WMAP, can be due to the synchrotron emission originated by neutralino self-annihilation; on the basis of this possible occurrence, also upper bounds on the neutralino self-annihilation cross--section are suggested. In the present note, we show that in the common case of thermal WIMPs in a standard cosmological model, when the rescaling of the galactic WIMP density is duly taken into account for subdominant WIMPs, the upper bound applicable generically to {\it any} signal due to self-conjugate WIMPs is more stringent than the ones obtained from analysis of the WMAP haze. We also argue that an experimental upper bound, which can compete with our generic upper limit, can rather be derived from measurements of cosmic antiproton fluxes, for some values of the parameters of the astrophysical propagation model. Finally, we comment on the possible impact of our generic upper bound on the interpretation of the WMAP haze in terms of thermal neutralinos in a standard cosmological scheme.Comment: 3 pages, comments and 1 figure adde

    Light Neutralinos and WIMP direct searches

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    The predictions of our previous analyses about possible low-mass (lower than 50 GeV) relic neutralinos are discussed in the light of the most 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.Comment: 4 pages, 1 figures, typeset with ReVTeX4. The paper may also be found at http://www.to.infn.it/~fornengo/papers/note.ps.gz or through http://www.to.infn.it/astropart/index.htm

    Implications for relic neutralinos of the theoretical uncertainties in the neutralino-nucleon cross-section

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    We discuss the effect induced on the neutralino-nucleon cross-section by the present uncertainties in the values of the quark masses and of the quark scalar densities in the nucleon. We examine the implications of this aspect on the determination of the neutralino cosmological properties, as derived from measurements of WIMP direct detection. We show that, within current theoretical uncertainties, the DAMA annual modulation data are compatible with a neutralino as a major dark matter component, to an extent which is even larger than the one previously derived. We also comment on implications of the mentioned uncertainties for experiments of indirect dark matter detection.Comment: 23 pages, 7 figures, 1 table, typeset with ReVTeX. Due to size limitations, the version on the archive has low resolution figures. A full version of the paper can be found at http://www.to.infn.it/~fornengo/papers/dama_sets.ps.g

    Implications of a possible 115 GeV supersymmetric Higgs boson on detection and cosmological abundance of relic neutralinos

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    We show that a supersymmetric neutral Higgs boson with a mass of about 115 GeV and with the other prerequisites required by the LEP Higgs events would be compatible with the detection of relic neutralinos in current set-ups for WIMP direct search. Thus this putative Higgs would fit remarkably well in an interpretation in terms of relic neutralinos of the annual-modulation effect recently measured in a WIMP direct experiment. We also show that the cosmological abundance of the relevant neutralinos reaches values of cosmological interest.Comment: 15 pages, 6 figures, typeset with ReVTeX. The new version containes extended analysis. In order to reduce size, the version on the archive has low-resolution figures. The paper with high-resolution figures can be found at http://www.to.infn.it/~fornengo/papers

    Possible implications of the channeling effect in NaI(Tl) crystals

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    The channeling effect of low energy ions along the crystallographic axes and planes of NaI(Tl) crystals is discussed in the framework of corollary investigations on WIMP Dark Matter candidates. In fact, the modeling of this existing effect implies a more complex evaluation of the luminosity yield for low energy recoiling Na and I ions. In the present paper related phenomenological arguments are developed and possible implications are discussed at some extent.Comment: 16 pages, 10 figures, preprint ROM2F/2007/15, submitted for publicatio

    Perspectives for Detection of a Higgsino-like Relic Neutralino

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    It has been conjectured by Ambrosanio, Kane, Kribs, Martin and Mrenna (AKM) that the CDF event ppˉ→e+e−γγ+missingETp \bar p \to e^+ e^- \gamma \gamma + missing E_T is due to a decay chain involving two neutralino states (the lightest and the next-to-lightest ones). The lightest neutralino (χAKM\chi_{AKM}) has been further considered by Kane and Wells as a candidate for cold dark matter. In this paper we examine the properties of relic χAKM\chi_{AKM}'s in their full parameter space, and examine the perspectives for detection by comparing theoretical predictions to sensitivities of various experimental searches. We find that for most regions of the parameter space the detectability of a relic χAKM\chi_{AKM} would require quite substantial improvements in current experimental sensitivities. The measurements of neutrino fluxes from the center of the Earth and of an excess of pˉ/p\bar{p}/p in cosmic rays are shown to offer some favorable perspectives for investigating a region of the χAKM\chi_{AKM} parameter space around the maximal tan⁥ÎČ\tan \beta value allowed by the model.Comment: 16 pages, LaTeX, 10 postscript figure