相关论文: Four-Quark Hadrons: an Updated Review
In the quark model, hadrons are dominantly bound states of quark-antiquark pairs (mesons) or three quarks (baryons), but QCD also allows hadronic states to be composed of more quarks bound together. Recently, BESIII, Belle and LHCb have…
Scores of exotic hadrons, particularly tetraquarks and pentaquarks in the heavy-quark sector, have been observed in the past 20 years, and more continue to be discovered to this day. Unlike mesons and baryons, such exotics are not mandated…
I give a brief account of current topics in description of exotic multiquark mesonic resonances with hidden heavy ($c$ or $b$) flavor, the so-called XYZ states, in terms of hadronic molecules and hadro-quarkonium systems. Also discussed are…
In recent years there has been a rapidly growing body of experimental evidence for existence of exotic, multiquark hadrons, i.e. mesons which contain additional quarks, beyond the usual quark-antiquark pair and baryons which consist of more…
In this talk we present some recent studies of multiquark components in the charmonium sector. We study the possible existence of compact four quark-states and meson-meson molecules in the charmonium spectroscopy.
It is shown that the exotic non-qqq hadrons of pentaquark $qqqq\bar{q}$ states can be clearly distinguished from the conventional qqq-baryon resonances or their hybrids if the flavor of $\bar{q}$ is different from any of the other four…
The recent confirmation of the charged charmonium like resonance Z(4430) by the LHCb experiment strongly suggests the existence of QCD multi quarks bound states. Some preliminary results about hypothetical flavored tetraquark mesons are…
The discovery of hadronic states beyond the conventional two-quark meson and three-quark baryon picture in the last two decades is one of the most amazing accomplishments in fundamental physics research. Many experiments contributed to this…
In the past decade, many new charmonium (or charmonium-like) and bottomonium (or bottomonium-like) states were observed experimentally. I will review these XYZ states which do not fit into the quark model spectrum easily.
The original charmonium two-body problem, like the $c\bar c$ structure of the $J/\psi$ meson, has become more involved in the last few years with the discovery of new resonances such as the tentative molecular state $X(3872)$ or the…
A number of new four-quark states containing from one to four charm or anti-charm quarks have been observed recently. Many of these new states have been discovered at the LHC. The production of these states via intrinsic charm in the proton…
Starting from 2003, the discovery of a large amount of the so-called exotic hadronic states, i.e., the $XYZ$ states, the pentaquark states as well as the tetraquark states, have not only revived studies of hadron spectroscopy, but also…
The lowest-lying charmonium-like tetraquarks $c\bar{c}q\bar{q}$ $(q=u,\,d)$ and $c\bar{c}s\bar{s}$, with spin-parity $J^P=0^+$, $1^+$ and $2^+$, and isospin $I=0$ and $1$, are systematically investigated within the theoretical framework of…
A number of candidate multiquark hadrons, i.e., particle resonances with substructures that are more complex than the quark-antiquark mesons and three-quark baryons that are prescribed in the textbooks, have recently been observed. In this…
Possible decays of four-quark mesons are studied by assigning the newly observed BABAR resonance to a four-quark meson with C=S=I=1. It is expected that some of them can be observed as narrow resonances. Implication of existence of…
A selected survey is presented of the recent progress in hadron spectroscopy. This includes spin-singlet charmonium states, excitations of charmonium and open-charm mesons, double-charm baryons, and pentaquark candidates. Models proposing…
A review of recent experimental developments concerning the $X$, $Y$ and $Z$ charmonium-like exotic states.
Discovery of the X(3872) meson in 2003 ignited intense interest in exotic (neither $q\bar{q}$ nor $qqq$) hadrons, but a $c\bar{c}$ interpretation of this state was difficult to exclude. An unequivocal exotic was discovered in the…
While the charmonium model has been effective in describing ccbar bound mesons, there have been many recently discovered charmonium-like states it cannot accommodate. Here I provide a review of recent results from the B-factories including…
In this talk we present a mechanism giving rise to exotic $XYZ$ four-quark states in the meson spectra within a constituent quark model approach. We discuss its generalization to five-quark states in the heavy baryon sector. Finally, we…