Search

We analyze the phenomenological consequences of assuming that the 125 GeV boson measured at the LHC coincides with one of the two CP-even Higgs bosons of an effective Minimal Supersymmetric extension of the Standard Model at the electroweak scale. We consider the two ensuing scenarios and discuss critically the role of the various experimental data (mainly obtained at colliders and at B-factories) which provide actual or potential constraints to supersymmetric properties. Within these scenarios, properties of neutralinos as dark matter particles are analyzed from the point of view of their cosmological abundance and rates for direct and indirect detections., Comment: 14 pages, 14 figures, typeset with ReVTeX4. A version of the paper with full resolution figures can be found at http://www.to.infn.it/~scopel/embedding.pdf

We review the status of the phenomenology of light neutralinos in an effective Minimal Supersymmetric extension of the Standard Model (MSSM) at the electroweak scale, in light of new results obtained at the CERN Large Hadron Collider. First we consider the impact of the new data obtained by the CMS Collaboration on the search for the Higgs boson decay into a tau pair, and by the CMS and LHCb Collaborations on the branching ratio for the decay $B_s \rightarrow {\mu}^{+} + {\mu}^{-}$. Then we examine the possible implications of the excess of events found by the ATLAS and CMS Collaborations in a search for a SM--like Higgs boson around a mass of 126 GeV, with a most likely mass region (95% CL) restricted to 115.5--131 GeV (global statistical significance about 2.3 $\sigma$). From the first set of data we update the lower bound of the neutralino mass to be about 18 GeV. From the second set of measurements we derive that the excess around $m^{SM}_H$ = 126 GeV, which however needs a confirmation by further runs at the LHC, would imply a neutralino in the mass range 18 GeV $\lsim m_{\chi} \lsim$ 38 GeV, with neutralino--nucleon elastic cross sections fitting well the results of the dark matter direct search experiments DAMA/LIBRA and CRESST., Comment: 10 pages, 6 figures, typeset with ReVTeX4. v2:discussion on LHC Higgs excess extended and one figure added. Matches version accepted for publication on Phys.Rev.D. A version of the paper with full resolution figures can be found at http://www.to.infn.it/~scopel/phenom_v2.pdf

We address the problem of a search at the LHC for a neutralino whose mass is around 10 GeV, i.e. in the range of interest for present data of direct search for dark matter particles in the galactic halo. This light neutralino is here implemented in an effective Minimal Supersymmetric extension of the Standard Model at the electroweak scale without requirement of a gaugino-mass unification at a grand unification scale. Within this model we select a representative benchmark and determine its prospects of reconstructing the main features of the model at different stages of the LHC runs., Comment: 24 pages, 11 figures, typeset with ReVTeX4

The long-standing model-independent annual modulation effect measured by the DAMA Collaboration, which fulfills all the requirements of a dark matter annual modulation signature, and the new result by the CoGeNT experiment that shows a similar behavior are comparatively examined under the hypothesis of a dark matter candidate particle interacting with the detectors' nuclei by a coherent elastic process. The ensuing physical regions in the plane of the dark matter-particle mass versus the dark matter-particle nucleon cross-section are derived for various galactic halo models and by taking into account the impact of various experimental uncertainties. It is shown that the DAMA and the CoGeNT regions agree well between each other and are well fitted by a supersymmetric model with light neutralinos which satisfies all available experimental constraints, including the most recent results from CMS and ATLAS at the CERN Large Hadron Collider., Comment: 13 pages, 7 figures

We discuss the impact for light neutralinos in an effective Minimal Supersymmetric extension of the Standard Model of the recent results presented by the CMS and ATLAS Collaborations at the CERN Large Hadron Collider for a search of supersymmetry in proton-proton collisions at a center-of-mass energy of 7 TeV with an integrated luminosity of 35 inverse pb. We find that, in the specific case of light neutralinos, efficiencies for the specific signature searched by ATLAS (jets+missing transverse energy and an isolated lepton) imply a lower sensitivity compared to CMS (which searches for jets +missing transverse energy). Focusing on the CMS bound, if squark soft masses of the three families are assumed to be degenerate, the combination of the ensuing constraint on squark and gluino masses with the experimental limit on the b to s + gamma decay imply a lower bound on the neutralino mass that can reach the value of 11.9 GeV, depending on the gluino mass. On the other hand, when the universality condition among squark soft parameters is relaxed, the lower bound on the neutralino mass is not constrained by the CMS measurement and then remains at the value 7.5 GeV derived in previous papers., Comment: 6 pages, 6 figures, typeset with ReVTeX4. A version of the paper with full resolution figures can be found at http://www.to.infn.it/~scopel/cms_mssm2.pdf

We examine the status of light neutralinos in an effective Minimal Supersymmetric extension of the Standard Model (MSSM) at the electroweak scale which was considered in the past and discussed in terms of the available data of direct searches for dark matter (DM) particles. Our reanalysis is prompted by new measurements at the Tevatron and B-factories which might potentially provide significant constraints on the MSSM model. Here we examine in detail all these new data and show that the present published results from the Tevatron and B-factories have only a mild effect on the original light neutralino population. This population, which fits quite well the DAMA/LIBRA annual modulation data, would also agree with the preliminary results of CDMS, CoGeNT and CRESST, should these data, which are at present only hints or excesses of events over the expected backgrounds, be interpreted as authentic signals of DM. For the neutralino mass we find a lower bound of 7-8 GeV. Our results differ from some recent conclusions by other authors because of a few crucial points which we try to single out and elucidate., Comment: 23 pages, 25 figures, typeset with ReVTeX4. One short section on indirect searches and a few references added. A version of the paper with full resolution figures can be found at http://www.to.infn.it/~scopel/light_2010.pdf

The first stars to form in the Universe may be powered by the annihilation of weakly interacting dark matter particles. These so-called dark stars, if observed, may give us a clue about the nature of dark matter. Here we examine which models for particle dark matter satisfy the conditions for the formation of dark stars. We find that in general models with thermal dark matter lead to the formation of dark stars, with few notable exceptions: heavy neutralinos in the presence of coannihilations, annihilations that are resonant at dark matter freeze-out but not in dark stars, some models of neutrinophilic dark matter annihilating into neutrinos only and lighter than about 50 GeV. In particular, we find that a thermal DM candidate in standard Cosmology always forms a dark star as long as its mass is heavier than about 50 GeV and the thermal average of its annihilation cross section is the same at the decoupling temperature and during the dark star formation, as for instance in the case of an annihilation cross section with a non-vanishing s-wave contribution., Comment: 17 pages, 4 figures, figure 1 fixed

The CDMS Collaboration has presented its results for the final exposure of the CDMS II experiment and reports that two candidate events for dark matter would survive after application of the various discrimination and subtraction procedures inherent in their analysis. We show that a population of relic neutralinos, which was already proved to fit the DAMA/LIBRA data on the annual modulation effect, could naturally explain the two candidate CDMS II events, if these are actually due to a dark matter signal., Comment: 3 pages, 3 figures

We present a detailed analysis of the neutrino-induced muon signals coming from neutralino pair-annihilations inside the Sun and the Earth with particular emphasis for light neutralinos. The theoretical model considered is an effective MSSM without gaugino-mass unification, which allows neutralinos of light masses (below 50 GeV). The muon events are divided in through-going and stopping muons, using the geometry of the Super-Kamiokande detector. In the evaluation of the signals, we take into account the relevant hadronic and astrophysics uncertainties and include neutrino oscillation and propagation properties in a consistent way. We derive the ranges of neutralino masses which could be explored at neutrino telescopes with a low muon-energy threshold (around 1 GeV) depending on the category of events and on the values of the various astrophysics and particle-physics parameters. A final analysis is focussed to the upward muon fluxes which could be generated by those neutralino configurations which are able to explain the annual modulation data of the DAMA/LIBRA experiment. We show how combining these data with measurements at neutrino telescopes could help in pinning down the features of the DM particle and in restraining the ranges of the many quantities (of astrophysics and particle-physics origins) which enter in the evaluations and still suffer from large uncertainties., Comment: 28 pages, 16 figures, a few references and minor comments added

We provide a detailed study of gravitational reheating in quintessential inflation generalizing previous analyses only available for the standard case when inflation is followed by an era dominated by the energy density of radiation. Quintessential inflation assumes a common origin for inflation and the dark energy of the Universe. In this scenario reheating can occur through gravitational particle production during the inflation-kination transition. We calculate numerically the amount of the radiation energy density, and determine the temperature $T_*$ at which radiation starts dominating over kination. The value of $T_*$ is controlled by the Hubble parameter $H_0$ during inflation and the transition time $\Delta t$, scaling as $H_0^2 [\ln(1/H_0\Delta t)]^{3/4}$ for $H_0 \Delta t \ll1$ and $H_0^2 (H_0 \Delta t)^{-c}$ for $H_0\Delta t \gg 1$. The model-dependent parameter $c$ is found to be around 0.5 in two different parametrizations for the transition between inflation and kination., Comment: 12 pages, 5 figures

The most recent results from direct searches for dark matter particles in the galactic halo are examined in terms of an effective Minimal Supersymmetric extension of the Standard Model at the electroweak scale without gaugino masses unification. We show that the annual modulation effect at 8.2 $\sigma$ C.L. recently presented by the DAMA Collaboration, as the result of a combined analysis of the DAMA/NaI and the DAMA/LIBRA experiments for a total exposure of 0.82 ton yr, fits remarkably well with what expected for relic neutralinos for a wide variety of WIMP distribution functions. Bounds derivable from other measurements of direct searches for dark matter particles are analyzed. We stress the role played by the uncertainties affecting the neutralino--quark couplings arising from the involved hadronic quantities. We also examine how present data on cosmic antiprotons can help in constraining the neutralino configurations selected by the DAMA effect, in connection with the values of the astrophysical parameters. Perspectives for measurement of antideuterons possibly produced in the galactic halo by self--annihilation of neutralinos belonging to the DAMA configurations are examined. Finally, we discuss how findings at LHC would impact on these issues., Comment: 18 pages, 10 figures a few minor comments and two references added

Two recent papers reconsider the possibility that the excess of microwave emission from a region within $\sim 20^0$ 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 added

We study how the properties of the four neutralino states, chi_i (i = 1, 2, 3, 4), can be investigated at the Large Hadron Collider (LHC), in the case when the lightest one, chi_1, has a mass m_chi < 50 GeV and is stable. This situation arises naturally in supersymmetric models where gaugino masses are not unified at a Grand Unified (GUT) scale and R-parity is conserved. The main features of these neutralino states are established by analytical and numerical analyses, and two scenarios are singled out on the basis of the cosmological properties required for the relic neutralinos. Signals expected at LHC are discussed through the main chain processes started by a squark, produced in the initial proton-proton scattering. We motivate the selection of some convenient benchmarks, in the light of the spectroscopical properties (mass spectrum and transitions) of the four neutralino states. Branching ratios and the expected total number of events are derived in the various benchmarks, and their relevance for experimental determination of neutralino properties is finally discussed., Comment: 21 pages, 17 figures

The DAMA Collaboration has recently analyzed its data of the extensive WIMP direct search (DAMA/NaI) which detected an annual modulation, by taking into account the channelling effect which occurs when an ion traverses a detector with a crystalline structure. Among possible implications, this Collaboration has considered the case of a coherent WIMP-nucleus interaction and then derived the form of the annual modulation region in the plane of the WIMP-nucleon cross section versus the WIMP mass, using a specific modelling for the channelling effect. In the present paper we first show that light neutralinos fit the annual modulation region also when channelling is taken into account. To discuss the connection with indirect signals consisting in galactic antimatter, in our analysis we pick up a specific galactic model, the cored isothermal-sphere. In this scheme we determine the sets of supersymmetric models selected by the annual modulation regions and then prove that these sets are compatible with the available data on galactic antiprotons. We comment on implications when other galactic distribution functions are employed. Finally, we show that future measurements on galactic antiprotons and antideuterons will be able to shed further light on the populations of light neutralinos singled out by the annual modulation data., Comment: 9 pages, 5 figures. A few comments and references added

We analyze leptogenesis in a supersymmetric triplet seesaw scenario that explains the observed neutrino masses, adopting a phenomenological approach where the decay branching ratios of the triplets and the amount of CP--violation in its different decay channels are assumed as free parameters. We find that the solutions of the relevant Boltzmann equations lead to a rich phenomenology, in particular much more complex compared to the non--supersymmetric case, mainly due to the presence of an additional Higgs doublet. Several unexpected and counter--intuitive behaviors emerge from our analysis: the amount of CP violation in one of the decay channels can prove to be be irrelevant to the final lepton asymmetry, leading to successful leptogenesis even in scenarios with a vanishing CP violation in the leptonic sector; gauge annihilations can be the dominant effect in the determination of the evolution of the triplet density up to very high values of its mass, leading anyway to a sizeable final lepton asymmetry, which is also a growing function of the wash--out parameter K=Gamma_d/H, defined as usual as the ratio between the triplet decay amplitude Gamma_d and the Hubble constant H; on the other hand, cancellations in the Boltzmann equations may lead to a vanishing lepton asymmetry if in one of the decay channels both the branching ratio and the amount of CP violation are suppressed, but not vanishing. The present analysis suggests that in the supersymmetric triplet see-saw model successful leptogenesis can be attained in a wide range of scenarios, provided that an asymmetry in the decaying triplets can act as a lepton--number reservoir., Comment: 14 pages, 6 figures

We consider the minimal supersymmetric triplet seesaw model as the origin of neutrino masses and mixing as well as of the baryon asymmetry of the Universe, which is generated through soft leptogenesis employing a CP violating phase and a resonant behavior in the supersymmetry breaking sector. We calculate the full gauge--annihilation cross section for the Higgs triplets, including all relevant supersymmetric intermediate and final states, as well as coannihilations with the fermionic superpartners of the triplets. We find that these gauge annihilation processes strongly suppress the resulting lepton asymmetry. As a consequence of this, successful leptogenesis can occur only for a triplet mass at the TeV scale, where the contribution of soft supersymmetry breaking terms enhances the CP and lepton asymmetry. This opens up an interesting opportunity for testing the model in future colliders., Comment: 17 pages, 5 figures; version accepted for publication

New upper bounds on direct detection rates have recently been presented by a number of experimental collaborations working on searches for WIMPs. In this paper we analyze how the constraints on relic neutralinos which can be derived from these results is affected by the uncertainties in the distribution function of WIMPs in the halo. Various different categories of velocity distribution functions are considered, and the ensuing implications for supersymmetric configurations derived. We conservatively conclude that current experimental data do not constrain neutralinos of small mass (below 50 GeV)., Comment: 9 pages, 7 figures, typeset with ReVTeX4. The paper may also be found at http://www.to.infn.it/~fornengo/papers/constraints05.ps.gz or through http://www.astroparticle.to.infn.it/index.html

We discuss the gamma-ray signal from dark matter annihilation in our Galaxy and in external objects, namely the Large Magellanic Cloud, the Andromeda Galaxy (M31) and M87. We derive predictions for the fluxes in a low energy realization of the Minimal Supersymmetric Standard Model and compare them with current data from EGRET, CANGAROO-II and HEGRA and with the capabilities of new-generation satellite-borne experiments, like GLAST, and ground-based Cerenkov telescopes, like VERITAS. We find fluxes below the level required to explain the possible indications of a gamma-ray excess shown by CANGAROO-II (toward the Galactic Center) and HEGRA (from M87). As far as future experiments are concerned, we show that only the signal from the galactic center could be accessible to both satellite-borne experiments and to ACTs, even though this requires very steep dark matter density profiles., Comment: 17 pages, 9 tables and 14 figures, typeset with ReVTeX4. A Figure and a comment on the recent HESS data have been added. The version on the archive has low-resolution figures. The paper with high resolution figures may be found through http://www.astroparticle.to.infn.it

We examine indirect signals produced by neutralino self-annihilations, in the galactic halo or inside celestial bodies, in the frame of an effective MSSM model without gaugino-mass unification at a grand unification scale. We compare our theoretical predictions with current experimental data of gamma-rays and antiprotons in space and of upgoing muons at neutrino telescopes. Results are presented for a wide range of the neutralino mass, though our discussions are focused on light neutralinos. We find that only the antiproton signal is potentially able to set constraints on very low-mass neutralinos, below 20 GeV. The gamma-ray signal, both from the galactic center and from high galactic latitudes, requires significantly steep profiles or substantial clumpiness in order to reach detectable levels. The up-going muon signal is largely below experimental sensitivities for the neutrino flux coming from the Sun; for the flux from the Earth an improvement of about one order of magnitude in experimental sensitivities (with a low energy threshold) can make accessible neutralino masses close to O, Si and Mg nuclei masses, for which resonant capture is operative., Comment: 17 pages, 1 tables and 5 figures, typeset with ReVTeX4. The paper may also be found at http://www.to.infn.it/~fornengo/papers/indirect04.ps.gz or through http://www.astroparticle.to.infn.it/. Limit from BR(Bs--> mu+ mu-) added

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.html

In the frame of an effective MSSM model without gaugino-mass unification at a grand unification (GUT) scale, we set a lower bound on the neutralino mass based on the new WMAP data on $\Omega_{CDM}$. Our lower bound, $m_{\chi} \gsim 6$ GeV, leaves much room for relic neutralinos significantly lighter than those commonly considered ($m_{\chi} \gsim 50$ GeV). We prove that these light neutralinos may produce measurable effects in WIMP direct detection experiments of low energy threshold and large exposure., Comment: 11 pages, 4 figures, typeset with ReVTeX4. Minor misprint corrected. To appear in PRD

We show that the main features of the annual modulation of the signal expected in a WIMP direct detection experiment, i.e. its sinusoidal dependence with time, the occurrence of its maxima and minima during the year and (under some circumstances) even the one-year period, may be affected by relaxing the isothermal sphere hypothesis in the description of the WIMP velocity phase space. The most relevant effect is a distortion of the time-behaviour at low recoil energies for anisotropic galactic halos. While some of these effects turn out to be relevant at recoil energies below the current detector thresholds, some others could already be measurable, although some degree of tuning between the WIMP mass and the experimental parameters would be required. Either the observation or non-observation of these effects could provide clues on the phase space distribution of our galactic halo., Comment: 4 pages, 4 figures, typeset with ReVTeX4. The paper may also be found at http://www.to.infn.it/~fornengo/papers/distortion.ps.gz

The relic abundance and the scalar cross-section off nucleon for light neutralinos (of mass below about 45 GeV) are evaluated in an effective MSSM model without GUT-inspired relations among gaugino masses. It is shown that these neutralinos may provide a sizeable contribution to the matter density in the Universe and produce measurable effects in WIMP direct detection experiments. These properties are elucidated in terms of simple analytical arguments., Comment: 11 pages, 4 figures, typeset with ReVTeX4. The paper may also be found at http://www.to.infn.it/~fornengo/papers/light.ps.gz Some comments and references added

After a short introduction on some general implications of recent cosmological observations, we discuss the properties of relic neutralinos in connection with present experimental strategies for detecting WIMPs., Comment: 10 pages, 4 figures, uses espcrc2.sty. Invited talk presented by A. Bottino at the First International Conference on "Particle and Fundamental Physics in Space (SPACE PART)", La Biodola, Isola d'Elba (Italy), May 2002. The paper may also be found at http://www.to.infn.it/~fornengo/proceedings/spacepart02.ps.gz

Since the thermal history of the Universe is unknown before the epoch of primordial nucleosynthesis, the largest temperature of the radiation dominated phase (the reheating temperature) might have been as low as 1 MeV. We perform a quantitative study of supersymmetric dark matter relic abundance in cosmological scenarios with low reheating temperature. We show that, for values of the reheating temperature smaller than about 30 GeV, the domains of the supergravity parameter space which are compatible with the hypothesis that dark matter is composed by neutralinos are largely enhanced. We also find a lower bound on the reheating temperature: if the latter is smaller than about 1 GeV neutralinos cannot be efficiently produced in the early Universe and then they are not able to explain the present amount of dark matter., Comment: 21 pages, 5 figures, typeset with ReVTeX4. The paper may also be found at http://www.to.infn.it/~fornengo/papers/reheating.ps.gz

We investigate whether present data on helioseismology and solar neutrino fluxes may constrain WIMP--matter interactions in the range of WIMP parameters under current exploration in WIMP searches. We find that, for a WIMP mass of 30 GeV, once the effect of the presence of WIMPs in the Sun's interior is maximized, the squared isothermal sound speed is modified, with respect to the standard solar model, by at most 0.4% at the Sun's center. The maximal effect on the Boron-8 solar neutrino flux is a reduction of 4.5%. Larger masses lead to smaller effects. These results imply that present sensitivities in the measurements of solar properties, though greatly improved in recent years, do not provide information or constraints on WIMP properties of relevance for dark matter. Furthermore, we show that, when current bounds from direct WIMP searches are taken into account, the effect induced by WIMPs with dominant coherent interactions are drastically reduced as compared to the values quoted above. The case of neutralinos in the minimal supersymmetric standard model is also discussed., Comment: 31 pages, 2 tables and 9 figures, typeset with ReVTeX4. The paper may also be found at http://www.to.infn.it/~fornengo/papers/helio.ps.gz or through http://www.to.infn.it/astropart/index.html

The DAMA/NaI Collaboration has observed a 4-sigma C.L. model independent effect investigating the annual modulation signature in the counting rate of an NaI(Tl) set-up (total exposure of 57986 kg day) and the implications of this effect have been studied under different model-dependent assumptions. In this paper we extend one of the previous analyses, the case of a WIMP with a purely spin-independent coupling, by discussing in detail the implications on the results of the uncertainties on the dark matter galactic velocity distribution. We study in a systematic way possible departures from the isothermal sphere model, which is the parameterization usually adopted to describe the halo. We specifically consider modifications arising from various matter density profiles, effects due to anisotropies of the velocity dispersion tensor and rotation of the galactic halo. The hypothesis of WIMP annual modulation, already favoured in the previous analysis using an isothermal sphere, is confirmed in all the investigated scenarios, and the effects of the different halo models on the determination of the allowed maximum-likelihood region in the WIMP mass and WIMP-nucleon cross-section are derived and discussed., Comment: 42 pages, 3 tables and 37 figures, typeset with ReVTeX4. A few typos corrected. The revised version matches the paper to appear in PRD. The paper may also be found at http://www.to.infn.it/~fornengo/papers/dama_distrib.ps.gz

Phenomenology of relic neutralinos is analyzed in an effective supersymmetric scheme at the electroweak scale. It is shown that current direct experiments for WIMPs, when interpreted in terms of relic neutralinos, are indeed probing regions of supersymmetric parameter space compatible with all present experimental bounds., Comment: 13 pages, 3 figures, typeset with ReVTeX. Invited talk presented by A. Bottino at COSMO-01, Rovaniemi, Finland, August 29 - September 4, 2001

We discuss the implications of a new determination of the pion-nucleon sigma term for the evaluation of the neutralino-nucleon cross-section, and, in turn, for detection rates for relic neutralinos in WIMP direct experiments and in some of the indirect searches. It is shown that the new range for the pion-nucleon sigma term, taken at its face value, favours values of the neutralino-nucleon cross-sections which are sizeably larger than some of the current estimates. Implications for neutralino cosmological properties are derived., Comment: 12 pages, 2 figures, typeset with ReVTeX

The CUORE (Cryogenic Underground Observatory for Rare Events) experiment projects to construct and operate an array of 1000 cryogenic thermal detectors of a mass of 760 g each to investigate rare events physics, in particular, double beta decay and non baryonic particle dark matter. A first step towards CUORE is CUORICINO, an array of 56 of such bolometers, currently being installed in the Gran Sasso. In this paper we report the physics potential of both stages of the experiment regarding neutrinoless double beta decay of 130Te, WIMP searches and solar axions., Comment: 30 pages, 5 figures, substantial changes in text and figures with respect to previous version

After a short introduction on particle candidates for dark matter within possible extensions of the standard model, we concentrate on Weakly Interacting Massive Particles, and on one of their most interesting physical realizations: the neutralino. We analyze how detectability of relic neutralinos by direct and indirect means is related to their local and cosmological densities; we use simple general arguments to discusss different scenarios where relic neutralinos make up the dominant bulk of dark matter or only a small fraction of it. Our general arguments are further corroborated by specific numerical results. We show to which extent the present experiments of direct searches for WIMPs, when interpreted in terms of relic neutralinos, probe interesting regions of the supersymmetric parameter space. Our analysis is performed in a number of different supersymmetric schemes., Comment: 26 pages, 6 figures, typeset with ReVTeX. Presented by A. Bottino at "Results and Perspectives in Particle Physics", Les Rencontres de Physique de la Vallee d'Aoste, La Thuile, March 2001. 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/lathuile01.ps.gz

A small, natural abundance, germanium detector (COSME) has been operating recently at the Canfranc Underground Laboratory (Spanish Pyrenees) in improved conditions of shielding and overburden with respect to a previous operation of the same detector. An exposure of 72.7 kg day in these conditions has at present a background improvement of about one order of magnitude compared to the former operation of the detector. These new data have been applied to a direct search for WIMPs and solar axions. New WIMP exclusion plots improving the current bounds for low masses are reported. The paper also presents a limit on the axion-photon coupling obtained from the analysis of the data looking for a Primakoff axion-to-photon conversion and Bragg scattering inside the crystal., Comment: LaTeX, 11 pages, 4 figures, submitted to Astropart. Phys

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/

Two germanium detectors are currently operating in the Canfranc Underground Laboratory at 2450 m.w.e looking for WIMP dark matter. One is a 2 kg 76Ge IGEX detector (RG-2) which has an energy threshold of 4 keV and a low-energy background rate of about 0.3 c/keV/kg/day. The other is a small (234 g) natural abundance Ge detector (COSME), of low energy threshold (2.5 keV) and an energy resolution of 0.4 keV at 10 keV which is looking for WIMPs and for solar axions. The analysis of 73 kg-days of data taken by COSME in a search for solar axions via their photon Primakoff conversion and Bragg scattering in the Ge crystal yields a 95% C.L. limit for the axion-photon coupling g < 2.8 10^-9 GeV^-1. These data, analyzed for WIMP searches provide an exclusion plot for WIMP-nucleon spin-independent interaction which improves previous plots in the low mass region. On the other hand, the exclusion plot derived from the 60 kg-days of data from the RG-2 IGEX detector improves the exclusion limits derived from other ionization (non thermal) germanium detector experiments in the region of WIMP masses from 30 to 100 GeV recently singled out by the reported DAMA annual modulation effect., Comment: 6 pages, talk given at IDM2000, York, September 2000

We discuss to which extent the present experiments of direct search for WIMPs, when interpreted in terms of relic neutralinos, probe interesting regions of the supersymmetric parameter space, which are also being progressively explored at accelerators. Our analysis is performed in a number of different supersymmetric schemes. We derive the relevant neutralino cosmological properties, locally and on the average in the universe. We prove that part of the susy configurations probed by current WIMP experiments entail relic neutralinos of cosmological interest. The main astrophysical and particle physics uncertainties, relevant for a proper comparison between theory and experimental data, are stressed and taken into account., Comment: 23 pages, 5 figures, typeset with ReVTeX. Updated to match version accepted for publication in PRD. 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/probing.ps.gz

Rare Objects SEarch with Bolometers UndergrounD) is an experiment which attempts to detect low mass Weak Interacting Massive Particles (WIMPs) through their elastic scattering off Al and O nuclei. It consists of three small sapphire bolometers (of a total mass of 100 g) with NTD-Ge sensors in a dilution refrigerator operating at 20 mK in the Canfranc Underground Laboratory. We report in this paper the results of several runs (of about 10 days each) with successively improved energy thresholds, and the progressive background reduction obtained by improvement of the radiopurity of the components and subsequent modifications in the experimental assembly, including the addition of old lead shields. Mid-term plans and perspectives of the experiment are also presented., Comment: 14 pages, 8 figures, submitted to Astroparticle Physics

The IGEX Collaboration enriched 76Ge double-beta decay detectors are currently operating in the Canfranc Underground Laboratory with an overburden of 2450 m.w.e. A recent upgrade has made it possible to use them in a search for WIMPs. A new exclusion plot has been derived for WIMP-nucleon spin-independent interaction. To obtain this result, 30 days of data from one IGEX detector, which has an energy threshold of ~4 keV, have been considered. These data improve the exclusion limits derived from other germanium diode experiments in the ~50 GeV DAMA region, and show that with a moderate improvement of the background below 10 keV, the DAMA region may be tested with an additional 1 kg-year of exposure., Comment: 7 pages, 2 figures, submitted to Physics Letters

We analyze the annual-modulation effect, measured by the DAMA Collaboration with the new implementation of a further two-years running, in the context of a possible interpretation in terms of relic neutralinos. We impose over the set of supersymmetric configurations, selected by the annual-modulation data, the constraints derived from WIMP indirect measurements, and discuss the features of the ensuing relic neutralinos. We critically discuss the sources of the main theoretical uncertainties in the analysis of event rates for direct and indirect WIMP searches., Comment: 29 pages, 12 figures, typeset with ReVTeX. In order to reduce size, 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/

Prospects of WIMP searches using the annual modulation signature are discussed on statistical grounds, introducing sensitivity plots for the WIMP-nucleon scalar cross section., Comment: 3 pages, 2 figures, talk given at TAUP'99, september 1999

A calculation of the expected signal due to Primakov coherent conversion of solar axions into photons via Bragg scattering in several solid-state detectors is presented and compared with present and future experimental sensitivities. The axion window m_a > 0.03 eV (not accessible at present by other techniques) could be explored in the foreseeable future with crystal detectors to constrain the axion-photon coupling constant below the latest bounds coming from helioseismology. On the contrary a positive signal in the sensitivity region of such devices would imply revisiting other more stringent astrophysical limits derived for the same range of the axion mass. The application of this technique to the COSME germanium detector which is taking data at the Canfranc Underground Laboratory leads to a 95% C.L. limit g_a < 2.8 10^-9 GeV^-1., Comment: 3 pages, 2 figures, talk given at TAUP'99, Paris, september 1999

Annual modulation due to the Earth's motion around the Sun is a well known signature of the expected WIMP signal induced in a solid state underground detector. In the present letter we discuss the prospects of this technique on statistical grounds, introducing annual-modulation sensitivity plots for the WIMP-nucleon scalar cross section for different materials and experimental conditions. The highest sensitivity to modulation is found in the WIMP mass interval 10 GeV< m_W < 130 GeV, the actual upper limit depending from the choice of the astrophysical parameters, while the lowest values of the explorable WIMP-nucleon elastic cross-sections fall in most cases within one order of magnitude of the sensitivities of present direct detection WIMP searches., Comment: 24 pages, ReVTeX, 9 figures, submitted to Astroparticle Physics

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.gz

The original annual-modulation region, singled out by the DAMA/NaI experiment for direct detection of WIMPs, is extended by taking into account the uncertainties in the galactic astrophysical velocities. Also the effect due to a possible bulk rotation for the dark matter halo is considered. We find that the range for the WIMP mass becomes 30 GeV < m_chi < 130 GeV at 1-sigma C.L. with a further extension in the upper bound, when a possible bulk rotation of the dark matter halo is taken into account. We show that the DAMA results, when interpreted in the framework of the Minimal Supersymmetric extension of the Standard Model, are consistent with a relic neutralino as a dominant component of cold dark matter (on the average in our universe and in our galactic halo). It is also discussed the discovery potential for the relevant supersymmetric configurations at accelerators of present generation., Comment: ReVTeX, 12 pages, 1 table, 7 figures

A calculation of the expected signal due to Primakoff coherent conversion of solar axions into photons via Bragg scattering in several crystal detectors is presented. The results are confronted with the experimental sensitivities of present and future experiments concluding that the sensitivity of crystal detectors does not challenge the globular cluster limit on the axion-photon coupling g_a. In particular, in the axion mass window m_a ~> 0.03 eV explored with this technique (not accessible at present by other methods) g_a might be constrained down to 10^-9 GeV^-1 (the recent helioseismological bound) provided that significant improvements in the parameters and performances of these detectors be achieved and large statistics accumulated. This bound should be considered as a minimal goal for the sensitivity of future crystal experiments. Consequently, finding a positive signal at this level of sensitivity would necessarily imply revisiting other more stringent astrophysical limits derived for the same range of m_a values., Comment: 12 pages, ReVTeX, 2 figures (included as PS files), submitted to Astroparticle Physics

A calculation of the expected signal due to Primakov coherent conversion of solar axions into photons via Bragg scattering in several solid--state detectors is presented and compared with present and future experimental sensitivities. The axion window m_a>~0.03 eV (not accessible at present by other techniques) could be explored in the foreseeable future with crystal detectors to constrain the axion--photon coupling constant below the latest bounds coming from helioseismology. On the contrary a positive signal in the sensitivity region of such devices would imply revisiting other more stringent astrophysical limits derived for the same range of the axion mass., Comment: 8 pages, 1 figure, To be published in the proceedings of the 2nd International Workshop on the Identification of Dark Matter (IDM98), Buxton, England, 7-11 September 1998

In previous papers we showed that the data of the DAMA/NaI experiment for WIMP direct detection, which indicate a possible annual modulation effect, are widely compatible with an interpretation in terms of a relic neutralino as the major component of dark matter in the Universe. In the present note we discuss the detectability of the relevant supersymmetric neutralino configurations by two of the most promising methods of indirect search for relic particles: measurement of cosmic-ray antiprotons and measurement of neutrino fluxes from Earth and Sun., Comment: 10 pages, ReVTeX, 8 figures (included as PS files)

Recent results of the DAMA/NaI experiment for WIMP direct detection point to a possible annual modulation effect in the detection rate. We show that these results, when interpreted in terms of a relic neutralino, are compatible with supergravity models. Together with the universal SUGRA scheme, we also consider SUGRA models where the unification condition in the Higgs mass parameters at GUT scale is relaxed., Comment: 10 pages, ReVTeX, 13 figures (included as PS files)

We demonstrate that the further indication of a possible annual modulation effect, singled out by the DAMA/NaI experiment for WIMP direct detection, is widely compatible with an interpretation in terms of a relic neutralino as the major component of dark matter in the Universe. We discuss the supersymmetric features of this neutralino in the Minimal Supersymmetric extension of the Standard Model (MSSM) and their implications for searches at accelerators., Comment: 15 pages, ReVTeX, 9 figures (included as PS files)

The effects of a possible rotation of the galactic dark halo on the calculation of the direct detection rates for particle dark matter are analyzed, with special attention to the extraction of the upper limits on the WIMP--nucleon scalar cross section from the experimental data. We employ a model of dark halo rotation which describes the maximal possible effects. For WIMP masses above 50 GeV, the upper limit exclusion plot is modified by less than a factor of two when rotation is included. For lighter masses the effect can be stronger, suggesting the necessity to develop specific models of halo rotation in order to provide more accurate conclusions., Comment: 14 pages, 7 figures included as PS files

The 8.4 Tesla, 10 m long transverse magnetic field of a twin aperture LHC bending magnet can be utilized as a macroscopic coherent solar axion-to-photon converter. Numerical calculations show that the integrated time of alignment with the Sun would be 33 days per year with the magnet on a tracking table capable of $\pm 5^o$ in the vertical direction and $\pm 40^o$ in the horizontal direction. The existing lower bound on the axion-to-photon coupling constant can be improved by a factor between 50 and 100 in 3 years, i.e., $g_{a\gamma\gamma} \lesssim 9\cdot 10^{-11} GeV^{-1}$ for axion masses $\lesssim$ 1 eV. This value falls within the existing open axion mass window. The same set-up can simultaneously search for low- and high-energy celestial axions, or axion-like particles, scanning the sky as the Earth rotates and orbits the Sun., Comment: Final version, accepted for publication in Nucl. Instr. Meth. A. More information can be found at http://wwwinfo.cern.ch/~collar/SATAN/alvaro.html