(Phys.org) —Two research teams working independently at two different particle   
   accelerators have found evidence of what appears to be a four-quark particle   
   that has come to be called Zc(3900). Both teams are made up of a large number   
   of researchers    
   affiliated with institutions from around the world and both have published   
   their findings in separate papers in the journal Physical Review Letters.    
      
   The discovery of what appears to be a new particle has come about at the two   
   sites (the Belle and BESIII experiments in Japan and China, respectively) as a   
   result of research into Y(4260), a particle discovered in 2005. Physicists   
   have been intrigued by    
   Y(4260) as it appears to be made of a charmed quark, an anti-charmed quark and   
   an extra gluon (in addition to the gluons holding the quarks together). In   
   studying the decay of Y(4260)—which is found in the debris after smashing   
   electrons and positrons    
   together in their respective accelerators—both research teams noticed a spike   
   of energy of about 3.9 gigaelectronvolts, which, as it turns out, is   
   approximately four times the weight of a proton. That suggested evidence of a   
   particle with four quarks,    
   something that has never been seen before.   
      
    Read more at:http://phys.org/news/2013-06-collider-teams-eviden   
   e-particle-z3900.html#ajTabs   
      
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