QCD Exotics

Abstract

QCD-motivated models for hadrons predict an assortment of "exotic" hadrons that have structures that are more complex then the quark-antiquark mesons and three-quark baryons of the original quark-parton model. These include pentaquark baryons, the six-quark H-dibaryon, and tetra-quark, hybrid, and glueball mesons. Despite extensive experimental searches, no unambiguous candidates for any of these exotic configurations have yet to be 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 so-called XYZ mesons-- and compare them with expectations for conventional quark-antiquark mesons and the predicted QCD-exotic states.

11 pages, 8 figures, to appear in the proceedings of LEAP 2013

References in corpus (7)

• Observation of a resonance-like structure in the pi^+- psi' mass distribution in exclusive B-->K pi^+- psi' decays
• The Exotic XYZ Charmonium-like Mesons
• Search for new charmonium states in the processes e+ e- --> J/psi D(*) D(*) at sqrt{s} ~ 10.6 GeV
• Determining the upper limit of Gamma_{ee} for the Y(4260)
• Searching for the Bottom Counterparts of X(3872) and Y(4260) via ${\pi }^{+}{\pi }^{-}{\rm Y}$
• Measurement of the B -> Dbar(*)D(*)K branching fractions
• Measurement of Time-Dependent CP-Violating Parameters in B0 -> K0S K0S decays

Cited by in corpus (1)

• Unexpected Mesons X, Y, Z, ... (tetraquarks? hadron molecules? ...)