Improved exclusion limits from the EDELWEISS WIMP search

The EDELWEISS experiment has improved its sensitivity for the direct search for WIMP dark matter. In the recoil energy range relevant for WIMP masses below 10 TeV/c2, no nuclear recoils were observed in the fiducial volume of a heat-and-ionization cryogenic Ge detector operated in the low-background environment of the Laboratoire Souterrain de Modane in the Fréjus Tunnel, during an effective exposure of 7.4 kg d. This result is combined with the previous EDELWEISS data to derive a limit on the cross-section for spin-independent interaction of WIMPs and nucleons as a function of WIMP mass, using standard nuclear physics and astrophysical assumptions. This limit excludes at more than 99.8% CL a WIMP candidate with a mass of 44 GeV/c2 and a cross-section of 5.4×10−6 pb, as reported by the DAMA Collaboration. A first sample of supersymmetric models are also excluded at 90% CL.