On December 30, Physics Magazine from the American Physical Society announced the top eleven highlights of the Year 2013 to the public. The observation of Four-quark matter, Zc(3900), the scientific achievement of the BESIII Collaboration was selected as top of this year’s highlights.
It is written in the magazine that “Quarks come in twos and threes—or so nearly every experiment has told us. This summer, the BESIII Collaboration in China and the Belle Collaboration in Japan reported they had sorted through the debris of high-energy electron-positron collisions and seen a mysterious particle that appeared to contain four quarks. Though other explanations for the nature of the particle, dubbed, are possible, the “tetraquark” interpretation may be gaining traction: BESIII has since seen a series of other particles that appear to contain four quarks”.
In the spring of 2013, the BESIII Collaboration reported the appearance of an electrically-charged particle, called the "Zc(3900)". A partner to the Zc(3900), the "Zc(4020)", was discovered in November using a method very similar to that used in the discovery of the Zc(3900). Another clue into the nature of all of these states came with the additional discovery of what appears to be the Y(4260) decaying to a photon and another particle called the "X(3872)." All the papers were published on Physical Review Letters.
The year 2013 has so far been an exciting one for the BESIII experiment. Using decays of the Y(4260), a family of four-quark objects has begun to appear. While the theoretical picture remains to be finalized, more and more clues are suggesting that we are witnessing new forms of matter. And while a new ‘zoo’ of mysterious particles is emerging, it seems a new classification system may soon be at hand to understand it.
The Physics editors made the list of the highlights of the year by taking a combination of factors into consideration, which includes the popularity on the website, a clear element of surprise or discovery, or signs that the work could lead to better technology.
For more information on the highlights of the year, please click:
http://physics.aps.org/articles/v6/139