Related papers: Multiquark Hadrons
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…
Results are presented on $\psi(2S)$ and $J/\psi$ hadronic decays to $K^0_SpK^-\bar n$ and $K^0_S\bar p K^+n$ final states from data samples of 14 million $\psi(2S)$ and 58 million $J/\psi$ events accumulated at the BES II detector. No…
In this work, we investigate the double-heavy molecular pentaquark states with the quark contents $ccss\bar{s}$, $bbss\bar{s}$, and $bcss\bar{s}$ by using the coupled channel approach. The extended local hidden gauge Lagrangians are used to…
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…
Within an extended chiral constituent quark model, three- and five-quark structure of the $S_{01}$ resonance $\Lambda(1405)$ is investigated. Helicity amplitudes for the electromagnetic decays ($\Lambda(1405) \to \Lambda(1116)\gamma$,…
Models proposed to explain recently discovered heavy-light four-quark states already assume certain internal structures, i.e. the (anti)quark constituents are grouped into diquark/antidiquark clusters, heavy-meson/light-meson clusters…
Using a constituent quark model we study the mass and decay channels of meson meson and meson baryon structures in the charm sector. We show that the $X(3872)$ and $X(3940)$ resonances can be described as mixed charmonium-molecular states…
Very recently, two hidden-charmed resonances $P_c(4380)$ and $P_c(4450)$ consistent with pentaquark states were observed at the LHCb detector. The two $P_c$ states locate just below the $\bar{D}\Sigma^*_c$ and $\bar{D}^*\Sigma_c$ thresholds…
In the framework of one-pion-exchange (OPE) model, we study the hidden-charm and charm-strange molecular pentaquark systems composed of a heavy baryon $(\Sigma_c, \Sigma_c^*)$ and a vector meson $(\bar{K}^*, \bar{D}^*)$, where the S-D…
Recent results on studies of exotic hadrons at the LHCb experiment are summarised. These are the observation of new resonances decaying to J/$\psi K^{+}$ and J/$\psi\phi$, evidence of a J/$\psi\Lambda$ structure and observation of excited…
A search for hidden-charm pentaquark states decaying to a range of $\Sigma_{c}\bar{D}$ and $\Lambda_{c}\bar{D}$ final states, as well as doubly-charmed pentaquark states to $\Sigma_{c}D$ and $\Lambda_{c}^{+}D$, is made using samples of…
The $\Lambda$ baryon spectrum is studied within the SU(3) flavor symmetry in a constituent quark model. We found that it is rather difficult to accommodate some negative-parity $\Lambda$ resonances as single $q^2s$ ($q = u,\,d$ quarks)…
A new approach to description of hadron spectroscopy is proposed. By assumption, the form of spectrum is dictated by the trace of energy momentum tensor in QCD. This provides the relativistic and renormalization invariance of hadron masses.…
Spontaneous chiral symmetry breaking, mesons and baryons are illustrated in the language of the Dirac theory. Various forces acting between quarks inside baryons are discussed. I explain why the naive quark models typically overestimate…
A review is presented of past and recent attempts to build multiquark states within current models already describing ordinary mesons and baryons. This includes: coherence in the chromomagnetic interaction, tetraquarks with two heavy…
A diquark model is used to investigate single charmed baryons. In this model, baryon is composed of two diquarks and an antiquark. Masses of lowest lying states with $J^P= 1/2 ^ \pm$ are obtained. Some masses are smaller than other…
Most of the exotic hadrons discovered over the last 20 years fit into the quark model as normal mesons and baryons if the existence of a seventh flavor of quark is hypothesized. If the quark has a mass of $\sim$2.9 GeV, a charge of…
The 2015 LHCb discovery of a structure (denoted by $P_c^+$) decaying in $J/\psi \,p$ and conjectured to be a penta-quark state, has triggered a renewed interest in the question of possible existence of multi-quark states not predicted by…
The angular distributions of the baryon-antibaryon low-mass enhancements seen in the charmless three-body baryonic B decays B^+ \to p pbar K^+, B^0 \to p pbar K_S^0, and B^0 \to p Lambdabar pi^- are reported. Searches for the pentaquarks…
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…