Related papers: Experimental Limits on the Width of the Reported T…
We investigate the impact of the \Theta^+(1540) resonance on differential and integrated cross sections for the reaction K^+d{\to}K^0pp, where experimental information is available at kaon momenta below 640 MeV/c. The calculation utilizes…
The recently reported Theta(1540) exotic baryon seems to be very narrow: Gamma(Theta)< 1 MeV according to some analyses. Using methods of low energy scattering theory, we develop expectations for the width of the Theta, an elastic resonance…
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…
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…
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…
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,…
If the exotic baryon $\Theta^+(1540)$ is a correlated $udud\bar{s}$ with $J^P = {1/2}^+$, then there should exist an exotic meson, $J^P = 1^-$ $\vartheta^+ (S=+2)$ $\to K^+K^0$ $\sim 1.6$GeV with width $O(10-100)$MeV. The $\pi_1(1400;1600)$…
It is suggested that the narrow width of the recently observed resonance $\Theta^{+}(1540)$ with strangeness $S=+1$ could be a result of the super-radiance mechanism of the redistribution of the widths of overlapping resonances due to their…
The data on the charge-exchange reaction K^+Xe --> K^0 p Xe, obtained with the bubble chamber DIANA, are reanalyzed using increased statistics and updated selections. Our previous evidence for formation of a narrow pK^0 resonance with mass…
The data on the reactions K^+Xe --> K^0 \gamma X and K^+Xe --> K^+ \gamma X, obtained with the bubble chamber DIANA, have been analyzed for possible radiative decays of the \Theta^+(1540) baryon: \Theta^+ --> K^0 p \gamma and \Theta^+ -->…
We outline how one can understand the Skyrme model from the modern perspective. We review the quantization of the SU(3) rotations of the Skyrmion, leading to the exotic baryons that cannot be made of three quarks. It is shown that in the…
The reaction K^+Xe->K^0pX is investigated in a meson-exchange model including rescattering of the secondary protons with the aim to analyze the evidence for the Theta^+(1540) resonance reported by the DIANA collaboration. We confirm that…
Twenty years ago, in 2003, two experimental groups, LEPS and DIANA, announced the discovery of a light, narrow, exotic baryon with mass within the range of 1540 MeV, which was later dubbed as $\Theta^+$. In this talk we recall the history…
The exclusive reaction $\gamma p \to \bar K^0 K^+ n$ was studied in the photon energy range between 1.6-3.8 GeV searching for evidence of the exotic baryon $\Theta^+(1540)\to nK^+$. The decay to $nK^+$ requires the assignment of strangeness…
In an exclusive measurement of the reaction $\gamma d \to K^+ K^- p n$, a narrow peak that can be attributed to an exotic baryon with strangeness $S=+1$ is seen in the $K^+n$ invariant mass spectrum. The peak is at $1.542\pm 0.005$…
Using kaon secondary interactions in the material of the Belle detector, we search for both inclusive and exclusive production of the Theta(1540)+. We set an upper limit of 2.5% at the 90% C.L. on the ratio of the Theta(1540)+ to…
We consider the effect of exotic S=+1 resonances Theta+ and Theta++ on K+p elastic scattering data (total cross section) and the process K0_Lp-->K0_Sp. Data near the observed Theta+(1540) are examined for evidence of additional states. The…
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…
We have used the light-cone formulation of Chiral-Quark Soliton Model to estimate the width of the lightest pentaquark Theta+. We have found that the effect of nonzero momentum transfer is important and reduces drastically the width to…
The status of our investigation of low-energy $K^+$Xe collisions in the Xenon bubble chamber DIANA is reported. In the charge-exchange reaction $K^+Xe \to K^0 p Xe'$ the spectrum of $K^0 p$ effective mass shows a resonant enhancement with…