Related papers: Pentaquark decay is suppressed by chirality conser…
Assuming that the recently observed hidden-charm pentaquark state, $P_c(4450)$, is of molecular nature as predicted in the unitary approach, we propose to study the decay of $\Xi^-_b\rightarrow J/\psi K^- \Lambda$ to search for the…
We report the recent results of the magnetic transitions and axial-vector transitions of the baryon antidecuplet within the framework of the chiral quark-soliton model. The dynamical model parameters are fixed by experimental data for the…
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…
H1 Collaboration recently observed the charmed pentaquark. In this short note, we point out that the dominant production mechanism for pentaquark consisting of a heavy quark is heavy quark fragmentation. We obtain a crude estimate on the…
For top-quarks produced via the subprocess $q\bar q\to t\bar t$, the longitudinal t-quark polarization ($P_{\parallel}$) vanishes in QCD. $P_{\parallel}$ can be measured by the angular distribution of the lepton in $t$-quark semileptonic…
Using dimensional regularization for both infrared and ultraviolet divergences, we confirm that the QCD corrections to the decay width $\Gamma(t\to H^+b)$ are equal to those to $\Gamma(t\to W^+b)$ in the limit of a large $t$ quark mass.
In this work, we systematically calculate transition magnetic moments, radiative decay widths, and axial-vector coupling constants of octet hidden-charm molecular pentaquark states with different flavor representations in constituent quark…
The exotic baryon $\Theta^+(uudd\bar{s})$ is studied with microscopic calculations in a quark model by using a method of antisymmetrized molecular dynamics. We predict that the lowest even state is $J^\pi=1/2^+(I=0)$ or $J^\pi=3/2^+(I=0)$,…
By using of vector diquark ideas in the chiral limit diquark correlations in the relativistic region and imposing HF interactions between quarks in a vector diquark we calculated the mass of two multiquark states (Theta pentaquark and H…
We construct QCD sum rules for the anti-charmed pentaquark $\Theta_c (3099)$, recently reported at HERA. The sum rules are constructed similarly with the $\Theta^+ (1540)$ sum rules using the anti-charmed analogue of the $\Theta^+$…
The problem of the long life time of the pentaquark $\Theta^+$ is investigated on the basis of the color molecular dynamics simulation. We find that it takes a long time (typically of 50-100 fm/c) for the initial pentaquark-state to…
Further consequences of the 1540 MeV Theta+ resonance as an isotensor pentaquark beyond Capstick et al. are explored. It is argued that the SAPHIR data may not currently exclude the existence of the charged partner Theta++. The usual…
We consider a $[ud]^2\bar{s}$ current in the QCD sum rule framework to study the mass of the recently observed pentaquark state $\Theta^+(1540)$, obtaining good agreement with the experimental value. We also study the mass of the pentaquark…
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…
The narrow width of the exotic narrow baryon resonance $\Theta^+$ might be explained by mixing between the two nearly degenerate states that arise in models with two diquarks and an antiquark. The only open $\Theta^+$ decay channel is $KN$.…
Baryon number conservation is an accidental symmetry in the Standard Model, but its violation is theoretically anticipated, making the search for such processes a promising avenue for discovering new physics. In this paper, we explore how…
The $SU(3)$-violating decays $\Phi^{2S} \goto \Phi^{1S} X$, where $X = \pi^0$ or $\eta$ and $\Phi = J/\psi$ or $\Upsilon$ have been recently proposed as a means of probing the light quark masses beyond leading order in chiral perturbation…
Top quark polarization in $e^+e^-$ annihilation into $t\bar t$ is calculated for linearly polarized beams. The Green function formalism is applied to this reaction near threshold. The Lippmann--Schwinger equations for the $S$-wave and…
Using the QCD string theory, we investigate the physical reason of the narrow width of penta-quark baryons in terms of the large gluonic-excitation energy. In the QCD string theory, the penta-quark baryon decays via a gluonic-excited state…
The two photon decay width of the neutral pion is analyzed within the combined framework of Chiral Perturbation Theory and the 1/Nc expansion up to order p^6 and p^4 times 1/Nc in the decay amplitude. The eta' is explicitly included in the…