Physicists confirm existence of new type of meson

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syracuseunivPhysicists in the College of Arts and Sciences at Syracuse University have made several important discoveries regarding the basic structure of mesons—subatomic particles long thought to be composed of one quark and one antiquark and bound together by a strong interaction.

Recently, Professor Tomasz Skwarnicki and a team of researchers proved the existence of a meson named Z(4430), with two quarks and two antiquarks, using data from the Large Hadron Collidor beauty (LHCb) Collaboration at CERN in Geneva, Switzerland. This tetraquark state was first discovered in Japan in 2007 but was later disputed by a team of researchers at Stanford University. Skwarnicki’s finding was published earlier this month and has since garnered international publicity.
Quarks are hard, point-like objects that are found inside protons and neutrons and form the nucleus of an atom.

Now, another analysis by Syracuse University physicists—this one led by Distinguished Professor Sheldon Stone and his research associate Liming Zhang—shows two lighter, well-known mesons, originally thought to be composed of tetraquarks, that are structured like normal mesons.
Stone says that one of the particles, uniquely named the f0(980), was assumed to have four quarks because it seemed to be the only way for its mass to “make sense.”
“The four-quark states cannot be classified within the traditional quark model, where strongly interacting particles [hadrons] are formed from either quark-antiquarks pairs [mesons] or three quarks [baryons],” says Stone, who also heads up Syracuse University’s High-Energy Physics Group. “They are, therefore, called ‘exotic particles.'”
Stone points out that his and Skwarnicki’s analyses are not contradictory and, together, increase what physicists know about the strong interaction that forms the basis of what holds all matter together.

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