QCD-motivated models for hadrons predict an assortment of ＂exotic＂ hadrons that have structures that are more complex than the quark-antiquark mesons and three-quark baryons of the original quark-parton model. These...QCD-motivated models for hadrons predict an assortment of ＂exotic＂ hadrons that have structures that are more complex than the quark-antiquark mesons and three-quark baryons of the original quark-parton model. These include pentaquark baryons： the six-quark H-dibaryon~ and tetraquark, hybrid and glueball mesons. Despite extensive experimental searches, no unambiguous candidates for any of these exotic configurations have been identified. On the other hand, a number of meson states, one that seems to be a proton-antiproton bound state, and others that contain either charmed- anticharmed quark pairs or bottom-antibottom quark pairs, have been recently discovered that neither fit into the quark-antiquark meson picture nor match the expected properties of the QCD- inspired exotics. Here I briefly review results from a recent search for the H-dibaryon, and discuss some properties of the newly discovered states -the proton-antiproton state and the so-called XYZ mesons- and compare them with expectations for conventional quark-antiquark mesons and the predicted QCD-exotic states.展开更多
文摘QCD-motivated models for hadrons predict an assortment of ＂exotic＂ hadrons that have structures that are more complex than the quark-antiquark mesons and three-quark baryons of the original quark-parton model. These include pentaquark baryons： the six-quark H-dibaryon~ and tetraquark, hybrid and glueball mesons. Despite extensive experimental searches, no unambiguous candidates for any of these exotic configurations have been identified. On the other hand, a number of meson states, one that seems to be a proton-antiproton bound state, and others that contain either charmed- anticharmed quark pairs or bottom-antibottom quark pairs, have been recently discovered that neither fit into the quark-antiquark meson picture nor match the expected properties of the QCD- inspired exotics. Here I briefly review results from a recent search for the H-dibaryon, and discuss some properties of the newly discovered states -the proton-antiproton state and the so-called XYZ mesons- and compare them with expectations for conventional quark-antiquark mesons and the predicted QCD-exotic states.
