Related papers: Vector and axial-vector structures of the Theta^+
We study determination of the parity of the pentaquark baryons in two different processes. First, we investigate the Theta^+ production via the vec{p} vec{p} -> Sigma^+ Theta^+ reaction process which was proposed to determine unambiguously…
Following a recent suggestion that the $\Theta ^+$ could be a $K \pi N$ bound state we perform an investigation under the light of the meson meson and meson baryon dynamics provided by the chiral Lagrangians and using methods currently…
For the first time, the reaction gamma d -> Lambda n K+ has been analyzed in order to search for the exotic pentaquark baryon Theta+(1540). The data were taken at Jefferson Lab, using the Hall-B tagged-photon beam of energy between 0.8 and…
We investigate the electric form factors and charge radii of the pentaquark baryons within the framework of the chiral quark-soliton model. We consider the rotational $1/N_c$ and linear $m_s$ corrections, assuming isospin symmetry and…
Using a hadronic model with empirical coupling constants and form factors, we have evaluated the cross sections for the production of exotic pentaquark $\Theta^+$ and/or $\Xi_5^+$ and $\Xi_5^{--}$ in reactions induced by photons, nucleons,…
By assuming SU(6)_cs symmetry for pentaquark decays one finds a selection rule, which strongly reduces the number of states able to decay into a baryon and a meson final state and allows an intriguing identification for the Theta^+ particle…
We study the interaction of the $\Theta^+$ pentaquark with nuclear matter associated to the $KN$ decay channels and to the two meson cloud. We find that the potential is attractive and could be strong enough to lead to the existence of…
A symmetry-preserving Dyson-Schwinger equation treatment of a vector-vector contact interaction is used to compute dressed-quark-core contributions to the nucleon $\sigma$-term and tensor charges. The latter enable one to directly determine…
We examine several assignments of spin and parity for the pentaquark Theta+ state (J^P=1/2^{+,-}, 3/2^{+,-}) in connection with known baryon resonances. Assuming that the Theta+ belongs to an antidecuplet representation which mixes with an…
We present a search for a narrow scalar or vector resonance decaying into Zgamma with a subsequent Z decay into a pair of electrons or muons. The data for this search were collected with the D0 detector at the Fermilab Tevatron ppbar…
We calculate the axial $N\to \Delta(1232)$ and $N\to N^{\star}(1440)$ transition form factors in a chiral constituent quark model. As required by the partial conservation of axial current ($PCAC$) condition, we include one- and two-body…
We analyze the problem of how to determine the parity of the $\Theta^+$ pentaquark in the reaction $\gamma N\to K\Theta\to NK\bar{K}$, where $N=n,p$. Our model calculations indicate that the contribution of the non-resonant background of…
We evaluate the radiative decay into a pseudoscalar meson and a photon of the whole set of the axial-vector mesons dynamically generated from the vector-pseudoscalar meson ($VP$) interaction. We take into account tree level and loop…
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…
The contradiction between evidence for and against the existence of the Theta+ pentaquark might be resolved if it only appears as a result of a particular production mechanism which is present in some experiments and absent in others. We…
We have continued our investigation of the charge-exchange reaction K^+ Xe --> K^0 p Xe' in the bubble chamber DIANA. In agreement with our previous results based on part of the present statistics, formation of a narrow p K^0 resonance with…
The mass and coupling of the axial-vector tetraquark $T_{bc;\bar{u}\bar{d} }^{0}$ (in a short form $T_{bc}^{0}$) are calculated by means of the QCD two-point sum rule method. In computations we take into account contributions arising from…
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…
We investigate the isovector axial vector and pseudoscalar form factors of $\Delta$ baryon by employing light-cone QCD sum rules. Numerical calculations show that the form factors can be well fitted by the exponential form. We make a…
We investigate the properties of different modifications to the linear $\sigma$-model (including a dilaton field associated with broken scale invariance) at finite baryon density $\rho$ and nonzero temperature $T$. The explicit breaking of…