Related papers: A pentaquark model of the negative parity Lambda(1…
At this point it is still unclear whether pentaquarks exist. While they have be seen in some experiments there are many experiments in which they are not found. On the assumption that pentaquarks exist, several authors have studied the…
A hypothesis of absolutely stable strange hadronic matter composed of $\Lambda(1405)$ baryons, here denoted $\Lambda^*$, is tested within many-body calculations performed using the Relativistic Mean-Field approach. In our calculations, we…
In this work we investigate the consequences of the Jaffe and Wilczek diquark model in the framework of QCD sum rules. An analysis of the Theta^+(1540) as (ud)^2\bar{s} state shows that the mass of the pentaquark is compatible with the…
In this talk, multiquarks are studied microscopically in a standard quark model. In pure ground-state pentaquarks the short-range interaction is computed and it is shown to be repulsive, a narrow pentaquark cannot be in the groundstate. As…
An interesting mass relation between down type quarks and charged leptons has been recently predicted within a supersymmetric SU(3)_c \times SU(2)_L \times U(1)_Y model based on the A4 flavor symmetry. Here we propose a simple extension…
We investigate the rare decay $\Lambda_b \to \Lambda \gamma$ which receives both short and long distance contributions. We estimate the long distance contributions and find them very small. The form factors are obtained from $\Lambda_c \to…
The stability of strange pentaquarks $uudd\bar s$ is studied in a constituent quark model based on a flavor-spin hyperfine interaction between quarks. With this interaction model, which schematically represents the Goldstone boson exchange…
We present an exploratory investigation of the parity odd $\Delta I = 1$ pion-nucleon coupling $h_\pi^1$ from lattice QCD. Based on the PCAC relation, we study the parity-conserving effective Hamiltonian and extract the coupling by…
Using the QCD Sum Rule Method, we estimate the mass of the lowest strange hybrid baryon with $IJ^P=0(1/2)^-$. We find the mass is approximately that of the $\Lambda(1405)$, whose nature has been a puzzle for many decades. Possible tests of…
Non-mesonic transition of Lambda(1405) N to YN is investigated as one of the essential processes for the non-mesonic absorption of Kbar in nuclei. Using one-meson exchange model in the calculation of the transition, we find that the…
A study of the decay channels Lambda_{b}-->Lambda V, where V is a vector meson (1^-), has been done by putting together kinematical and dynamical analysis. An intensive use of the helicity formalism is involved on the kinematical side,…
A search for narrow Theta(1540)^+, a candidate for pentaquark baryon with positive strangeness, has been performed in an exclusive proton-induced reaction p+C(N) \to Theta^+ \bar{K}^0 + C(N) on carbon nuclei or quasifree nucleons at…
We extend our relativistic quark model to the study of the decay Lambda_b -> Lambda_c ell nu and verify that the model satisfies the heavy-quark symmetry constraints at order 1/mQ^2. We isolate a strong dependence on a parameter which…
The spectrum of heavy-hadron molecules is constrained by heavy-quark symmetry in its different manifestations. Heavy-quark spin symmetry for instance connects the properties of the ground and excited states of heavy hadrons, while…
Two body weak processes $\Lambda N \leftrightarrow NN$ are studied from the viewpoint of quark substructure of baryons.They can be studied in nonmesonic weak decays of hypernuclei and also hyperon production in the $NN$ scattering. The…
QCD instantons are known to produce deeply bound diquarks. We study whether it may be used as building blocks in the formation of multiquark states, in particular pentaquarks and dibaryons. A simple model is presented in which the lowest…
The LHCb collaboration have recently updated their analysis of the resonant $J/\psi\, p$ mass spectrum in the decay $\Lambda_b^0 \to J/\psi\, p\, K^-$, making use of their combined Run~1 and Run~2 data. In the updated analysis, three narrow…
We have recently studied hidden-charm pentaquarks, $c\bar c qqq$, using dynamical correlations between the heavy quarks arising from the Coulomb-like nature of the short-range interaction. A pattern was obtained that compares well with the…
The recently observed pentaquark baryons $\Theta^{+}$ and $\Xi^{--}$ are studied in the dual gravity theory of QCD. By developing a general formulation useful for studying the branched string web in a curved space, simple mass formulae of…
Heavy-quark interactions in the Quark-Gluon Plasma are analyzed in terms of a selfconsistent Brueckner scheme using a thermodynamic $T$-matrix based on a potential model. The interrelations between quarkonium correlators, spectral functions…