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Strongest limit for the mass of 'mysterious' dark matter set.

Washington, Nov 24 (ANI): Though the presence of dark matter in the universe remains a mystery, Brown University physicists have set the strongest limit to date on its mass.

The mysterious particles are believed to make up nearly a quarter of the universe.

The University's assistant professor Savvas Koushiappas and graduate student Alex Geringer-Sameth reported that dark matter must have a mass greater than 40 giga-electron volts in dark-matter collisions involving heavy quarks.

They constrained the mass of dark matter particles by calculating the rate at which the particles are thought to cancel each other out in galaxies that orbit the Milky Way galaxy using publicly available data collected from an instrument on NASA's Fermi Gamma-ray Space Telescope and a novel statistical approach.

"What we find is if a particle's mass is less than 40 GeV, then it cannot be the dark matter particle," Koushiappas said.

The observational measurements are important because they cast doubt on recent results from dark matter collaborations that have reported detecting the elusive particle in underground experiments.

Those collaborations - DAMA/LIBRA, CoGeNT and CRESST - said they found dark matter with masses ranging from 7 to 12 GeV, less than the limit determined by the Brown physicists.

"If for the sake of argument a dark matter particle's mass is less than 40 GeV, it means the amount of dark matter in the universe today would be so much that the universe would not be expanding at the accelerated rate we observe," Koushiappas said.

The Fermi-LAT Collaboration, an international scientific collaboration, arrived at similar results, using a different methodology.

The results will be published on Dec. 1 in Physical Review Letters. (ANI)

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Publication:Asian News International
Date:Nov 24, 2011
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