Related papers: Theta+ width estimation with nonzero momentum tran…

We discuss the relatively low mass and narrow width prediction for the exotic baryon Theta+, and comment on recent statements by R.L. Jaffe on the subject. We reaffirm that a narrow width of 3.6-11.2 MeV follows from the equations of our…

In 1997 Diakonov, Petrov, and Polyakov, calculated the width of the exotic baryon that they called $\Theta^{+}$. The prediction, $\Gamma(\Theta^{+})\lesssim$ 15 MeV, has received considerable attention, especially in light of the narrowness…

Recently, Diakonov and Petrov have suggested a formalism in the Relativistic Mean Field Approximation allowing one to derive the 3-, 5-, 7-,... quark wavefunctions for the octet, decuplet and antidecuplet. They have used this formalism and…

We estimate the mass and the width of pentaquark $\Theta^*$ states in the 27-plet from chiral soliton models. The calculations show that the mass of $\Theta^*$ is about 1.60 GeV and the width for the process $\Theta^*\to {KN}$ is less than…

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…

The charge-exchange reaction K^+ Xe --> K^0 p Xe' is investigated using the data of the DIANA experiment. The distribution of the pK^0 effective mass shows a prominent enhancement near 1538 MeV formed by \sim 80 events above the background,…

Using the results of the GRAAL collaboration on the \eta photoproduction from the neutron target, we attempt to extract the partial radiative width of the possible new nucleon resonance N^*(1675). The obtained estimates support this…

We present in this talk recent results of the vector and axial-vector transitions of the nucleon to the pentaquark baryon Theta^{+}, based on the SU(3) chiral quark-soliton model. The results are summarized as follows: K^{*}-N-Theta vector…

The properties of the Theta^{+} and Xi^{--}_{3/2} exotic baryons have been investigated in the framework of diquark- diquark-antiquark system. A model for diquark suggested in an analogy with the quasi-particle in a crystal lattice has been…

Using data on K^+ collisions on xenon and deuterium we derive values and limits on the width of the reported Theta(1540)^+ exotic baryon resonance. The xenon experiment gives a width of 0.9\pm 0.3 MeV. The other experiments give upper…

We study properties of the pentaquark particle Theta+ with emphasis on the role of chiral symmetry. It is shown that when chiral force is sufficiently strong, the positive parity Theta+ may be realized with a lower mass relative to the…

I overview the physical picture of QCD at low energies that has led to the prediction of a narrow exotic baryon Theta^+ which cannot be made of three quarks. The very narrow width of the Theta^+ and a possible reason why it is seen in low-…

A narrow resonance peak was observed at 1.54 +/- 0.01 GeV as an exotic baryon with strangeness S = +1 in the gamma + n going to K^+ + K^- + n reaction on Carbon. The new state have a width smaller than 0.025 GeV and a Gaussian significance…

Several recent experiments have reported evidence for a narrow baryon resonance with positive strangeness ($\Theta^+$) at a mass of 1.54 GeV/$c^2$. Baryons with $S=+1$ cannot be conventional $qqq$ states and the reports have thus generated…

In this talk I report on a thorough comparison between the bound state and rigid rotator approaches to generate baryon states with non--zero strangeness in chiral soliton models. This comparison shows that the scattering amplitude in the…

The experimental status of the pentaquark searches is briefly reviewed. Recent null results by the CLAS collaboration are commented, and new strong evidence of a very narrow Theta+ resonance by the DIANA collaboration is presented. On the…

In the Relativistic Mean Field Approximation three quarks in baryons from the lowest octet and the decuplet are bound by the self-consistent chiral field, and there are additional quark-antiquark pairs whose wave function also follows from…

Using the exisiting experimental data for hyperon semileptonic decays and the flavor-singlet axial-vector charge $g_{A}^{(0)}$ from polarized deep inelastic scattering of the proton, we derive the decay width of the $\Theta^{+}$ pentaquark…

We perform a QCD sum rule analysis for the pentaquark baryon Theta^+ with the non-interacting $KN$ contribution treated carefully. The coupling of the Theta^+ current to the $KN$ state is evaluated by applying the soft kaon theorem and…

The data on hadron--nucleus collisions at 400--700 GeV, collected by the SELEX experiment at Fermilab, are analyzed for formation of the exotic pentaquark baryon $\Theta^+(1540)$. A narrow enhancement near 1539 MeV is observed in the mass…