BESIII and Belle found evidence for a new particle

On June 17, an article on the observation of a charged charmoniumlike structure at BESIII was published in Physical Review Letters (Volume

 
 four-quark combinations that may explain theZc(3900) observations.(image by APS/Alan Stonebraker)
110, Issue 25). A paper from Belle Experiment at KEK appeared on the same issue, which signified that the two experiments have more or less simultaneously detected the signature of a new particle, called the Zc(3900 ).

Since its 2005 discovery by the BaBar experiment at the SLAC National Laboratory in Stanford California, the Y(4260) particle has continued to mystify researchers. Both the BESIII Experiment at the Beijing Electron Positron Collider in China and the Belle experiment at the Japanese High Energy Accelerator Research Organization (KEK) focused on the research of this particle, and found the even more mysterious particle, the Zc(3900).

The experiments have now produced more than 460 of these strange Zc(3900) particles, suggesting that they are real phenomena and not simply a statistical fluke in the data. The new exotic particle appears to have an electric charge, and contains at least a charm quark, an anti-charm quark, an up quark, and an anti-down quark for a total of four quarks.

"We haven’t seen anything like that before and for that reason it’s exciting,” commented Eric Swanson, an associate professor at the University of Pittsburgh, While previous experiments have detected hints of such particles, BESIII and Belle’s data are the cleanest and most experimentally solid to date.”

The next step for both collaborations is to produce more new Zc(3900) particles and watch how they decay, which should give some clues as to their properties, for example, whether it is a molecule of two mesons or a tetraquark state or other possibilities suggested by the theorists But in any case, the Zc(3900) is something extremely interesting for a deeper understanding of the matters in the universe.

the data bump from BESIII and Belle (images from physics review letter)

Sources from:

BESIII paper: http://prl.aps.org/abstract/PRL/v110/i25/e252001

Belle paper: http://prl.aps.org/abstract/PRL/v110/i25/e252002

BESIII news: http://english.ihep.cas.cn/prs/ns/201303/t20130326_100230.html

Eric Swanson’s article: http://physics.aps.org/articles/v6/69

News on Wired Magazine: http://www.wired.com/wiredscience/2013/06/four-quark-particle/

Nature: http://www.nature.com/news/quark-quartet-opens-fresh-vista-on-matter-1.13225

Live Science: http://www.livescience.com/37546-new-particle-four-quarks.html

PHYS.ORG: http://phys.org/news/2013-06-collider-teams-evidence-particle-z3900.html