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Sunday, May 18, 2014

The End Of An Era

J. Robert Oppenheimer

It is the end of an era, not the nuclear era - unfortunately - for nukes are still around, but it is the end of a time, a small saeculum (a period of time) whose beginnings we can just feel and who ending is slipping by us unnoticed.

 Niels Bohr

HADES searches for dark matter
May 12, 2014
Although Dark Energy and Dark Matter appear to constitute over 95 percent of the universe, nobody knows of which particles they are made up. Astrophysicists now crossed one potential Dark Matter candidate – the Dark Photon or U boson – off the list in top position. This is the result of recent HADES experiments, where researchers from the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) and from 17 other European institutes try to pin down the nature of Dark Matter. These negative results – recently published in Physics Letters B – could even lead to challenges of the Standard Model of particle physics.


While evidences for the Higgs boson were found recently at CERN, the Standard Model looks now complete when supplemented by some neutrino masses, and nothing else seems to be needed to understand the wealth of atomic, sub-nuclear and particle physics phenomena. Nevertheless, Dark Matter appears not to be explained by any of the constituents of the Standard Model. This status of the affair has initiated worldwide efforts to search for Dark Matter candidates.

Albert Einstein
Up to now the search for such a signal of a U boson as a candidate for Dark Matter has remained unsuccessful. Together with many other searches for the other candidates of Dark Matter the situations becomes more and more intricate. Cosmology on precision level requires the existence of Dark Matter; however, the various experiments have not found any positive hint. The negative results on the U boson by HADES and other experiments make the hunt for new physics beyond the Standard Model more challenging.


The HADES collaboration has accumulated more than ten billion analyzable events during the last years. The notion "events" means that in collisions of energetic protons with target protons or atomic nuclei or in collisions of atomic nuclei with target nuclei, among other final-state particles, an electron-positron pair could occur. Sources of these pairs are, e.g., unstable hadrons being transiently produced in these collisions. The highly sophisticated apparatus HADES has the capability to select out of a huge background of other particles such electron-positron pairs which can be attributed to primary sources.

 Peter Higgs

Something terrifically new is in the air.
The Ptolemaic Dark Matter quest will come to a timely end, and... something new.


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