Related papers: Exotics and PWA for piN Scattering
We propose a collective stringlike model of pentaquarks with the geometry of an equilateral tetrahedron in which the four quarks are located at the four corners and the antiquark in its center. The nonplanar equilibrium configuration is a…
We study the recently discovered Theta^+ baryon in the context of the perturbative chiral quark model. The basic configuration of the Theta^+ is set up as a pentaquark bound state, where the single particle wave functions are the ground…
Recent evidence for pentaquark baryons in the channels $\Xi^-\pi^-$, $\Xi^-\pi^+$ and their anti-particles claimed by the NA49 collaboration is critically confronted with the vast amount of existing data on $\Xi$ spectroscopy which was…
The nucleon wave function may contain a significant component of ssbar pairs, according to several measurements including the pi-nucleon sigma term, charm production and polarization effects in deep-inelastic scattering. In addition, there…
This invited contribution summarizes some of the more important aspects of exotics. We review theoretical expectations for exotic and nonexotic hybrid mesons, and briefly discuss the leading experimental candidate for an exotic, the…
A general study of pentaquarks built with four quarks in a L=1 state and an antiquark in S-wave shows that several of such states are forbidden by a selection rule, which holds in the limit of flavour symmetry, to decay into a baryon and a…
Early data on $K^-$ induced reactions off protons are collected and used in a coupled-channel partial wave analysis (PWA). Data which had been published in the form of Legendre coefficients are included in the PWA. In a {\it primary} fit…
Baryon resonance state with strangeness $S = +1$ observed in systems $p K^0$ and $n K^+$ is interpreted as a result of the decay $N^{*+} \to p \eta$ of the well-known resonance $N^*(1535)$ (with spin-parity $j^P = {1/2}^-$ and mass $m…
We apply a quark interchange model to spin-dependent and exotic meson-meson scattering. The model includes the complete set of standard quark model forces, including OGE spin-orbit and tensor and scalar confinement spin-orbit. Scattering…
Theoretical considerations prompted by discovery of the exotic Theta(uudds*) baryon led us to propose a dynamical picture emphasizing the role of diquark correlations, which are also useful in elucidating other aspects of low-energy QCD. A…
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 recent search for non $q \bar{q}$ mesons in $\pi^{-}p$ interactions at Brookhaven National Laboratory is summarized. Many final states such as $\eta \pi$, $\eta' \pi^{-}$, $a_{0} \pi$, $f_{1} \pi$, $a_{2} \pi$, $b_{1} \pi$, which are…
Based on the fact that the long expected pentaquark which possesses the exotic quantum numbers of $B=1$ and $S=1$ was not experimentally found, although exotic states of $XYZ$ have been observed recently, we conjecture that the heavy…
We re-analyze the predictions of chiral-soliton models for the masses and decay widths of baryons in the exotic antidecuplet of flavour SU(3). The calculated ranges of the chiral-soliton moment of inertia and the \pi-nucleon scattering…
Recently observed exotic baryon resonance with positive strangeness is discussed. The chiral soliton model, which allowed to predict the mass and width of this state, predicts also a number of other exotic states, strange and non-strange,…
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…
We investigate the spin 3/2 baryons in the 27-plet based on flavor SU(3) symmetry. For $J^p=3/2^+$, we find all the candidates for non-exotic members. For $J^p=3/2^-$, we predict a new non-exotic member $\Lambda(1780)$. Fitting the mass…
We study supersymmetric extra U(1) model with $S_4$ flavor symmetry. The flavor symmetry not only stabilizes proton but also suppresses the flavor changing processes without raising the supersymmetry breaking scale. After the flavor…
We study the weak decay of the $\Lambda_b$ baryon into $J/\psi\ \phi\ \Lambda$, a process that is particularly well suited to analyze the physics of some of the recently observed or theoretically predicted exotic hadrons, as one expects to…
We study the self-energy of the SU(3) antidecuplet coming from two-meson virtual clouds. Assuming that the exotic Theta+ belongs to an antidecuplet representation with N(1710) as nucleon partner, we derive effective Lagrangians that…