S. Scopel

Effect of the galactic halo modeling on the DAMA/NaI annual modulation result: an extended analysis of the data for WIMPs with a purely spin-independent coupling

The DAMA/NaI Collaboration has observed a 4–� 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.

Neutralino dark matter in supersymmetric models with non-universal scalar mass terms

Abstract Neutralino dark matter is studied in the context of a supergravity scheme where the soft scalar mass terms are not constrained by universality conditions at the grand unification scale. We analyse in detail the consequences of the relaxation of this universality assumption on the supersymmetric parameter space, on the neutralino relic abundance and on the event rate for the direct detection of relic neutralinos.

Probing the supersymmetric parameter space by weakly interacting massive particle direct detection

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.

A decommissioned LHC model magnet as an axion telescope

The 8.4 T, 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/yr with the magnet on a tracking table capable of

Search for solar axions by Primakoff effect in NaI crystals

5i in the vertical direction and

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

40i in the horizontal direction. The existing lower bound on the axion-to-photon coupling constant can be improved by a factor between 30 and 100 in 3 yr, i.e., g !cc [9]10~11 GeV~1 for axion masses [ 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. ( 1999 Elsevier Science B.V. All rights reserved.

Neutralino annihilation into {gamma} rays in the Milky Way and in external galaxies

The results of a search for possible signal due to Primakoff coherent conversion of solar axions into photons in NaI(Tl) are presented. The experiment has been carried out at the Gran Sasso National Laboratory of INFN; the used statistics is 53437 kg day. The presently most stringent experimental limit on g(a gamma gamma) from this process is obtained: g(a gamma gamma) < 1.7 x 10(-9) GeV-1 (90% C.L.). In particular, the axion mass window m(a) greater than or similar to 0.03 eV, not accessible by other direct methods, is explored and KSVZ axions with mass larger than 4.6 eV are excluded at 90% C.L

Light relic neutralinos

Abstract 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.

Light neutralinos and WIMP direct searches

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 atmospheric Cerenkov telescopes (ACTs), even though this requires very steep dark matter density profiles.

Extending the DAMA annual-modulation region by inclusion of the uncertainties in astrophysical velocities

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 with R-parity conservation and 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. A lower bound on the neutralino mass m x ≳ 6 GeV, based on the new WMAP data on Ω CDM, is worked out