Still Quiet is Dark Matter

Cosmological observations suggest the existence of dark matter, which has not shown any traces of interacting with known baryonic matter. Yet, dark matter comprises over 80% of the total matter needed to explain the space-time structure. Scientists have not a clue regarding the nature of these matter. One proposal says they may be made of sort of particles, the so-called WIMPs (weakly interacting massive particles). Various experiments have been devised to detect them. NO positive results exist up to now. A latest effort came in PRL, still no activities of these particles detected. They are really quiet, should they be there. [Phys. Rev. Lett. 105, 131302 (2010)]

The XENON100 experiment, in operation at the Laboratori Nazionali del Gran Sasso in Italy, is designed to search for dark matter weakly interacting massive particles (WIMPs) scattering off 62 kg of liquid xenon in an ultralow background dual-phase time projection chamber. In this Letter, we present first dark matter results from the analysis of 11.17 live days of nonblind data, acquired in October and
November 2009. In the selected fiducial target of 40 kg, and within the predefined signal region, we observe no events and hence exclude spin-independent WIMP-nucleon elastic scattering cross sections above 3:4 10 44 cm2 for 55 GeV=c2 WIMPs at 90% confidence level. Below 20 GeV=c2, this result
constrains the interpretation of the CoGeNT and DAMA signals as being due to spin-independent, elastic, light mass WIMP interactions.