Related papers: Determining Pentaquark Quantum Numbers from Strong…
Observations of exotic structures in the $J/\psi p$ channel, that we refer to as pentaquark-charmonium states, in $\Lambda_b^0\to J/\psi K^- p$ decays are presented. The data sample corresponds to an integrated luminosity of 3/fb acquired…
Recent strong experimental evidence of a narrow exotic S = +1 baryon resonance, $\Theta^+$, suggests the existence of other exotic baryons. We discuss the prospects of confirming earlier experimental evidence of $\Theta^+$ and the…
We discuss the quantum state structure on the basis of $SU(3)_c$ for some known exotic quark systems using a model which describes these particular states as highly correlated diquarks and antidiquarks. We are then able to calculate for a…
We estimate the mass of the pentaquark state with QCD sum rules and find that pentaquark states with isospin $I=0, 1, 2$ lie close to each other around $(1.55\pm 0.15)$ GeV. The experimentally observed baryon resonance $\Theta^+ (1540)$…
It is argued that exotic mesons consisting of two quarks and two antiquarks are not ruled out in quantum chromodynamics with a large number $N$ of colors, as generally thought. They can come in two varieties: short-lived tetraquarks with…
The earlier search at HERMES for narrow baryon states excited in quasi-real photoproduction, decaying through the channel $pK_S^0\rightarrow p\pi^+\pi^-$, has been extended with improved decay-particle reconstruction, more advanced particle…
The newly discovered exotic $\Theta$ baryon of mass 1540 MeV (and very small width) truly has a very low mass, if it is a pentaquark system of even parity. A schematic model in which the coherent interaction of $u\bar s$ and $d\bar s$ pairs…
We present an exact calculation of $S$ and $P$ wave $QQ\bar n\bar n$ states using different standard nonrelativistic quark--quark potentials. We explore in detail the charm and bottom sectors looking for bound states that could be measured…
In this talk I review the theory of electromagnetic decays of the ground state baryon multiplets with oneheavy quark, calculated using Heavy Hadron Chiral Perturbation Theory. The M1 and E2 amplitudes for (S^{*}-> S gamma), (S^{*} -> T…
We apply the method of QCD sum rules to study the doubly heavy tetraquark states $QQ\bar{q}\bar{n}$ with spin-parity $J^{P}=1^{+}$ and strangeness $S=0, -1$ using careful estimates of the Borel and threshold parameters involved. Masses of…
In this work, the multiquark approach is used to analyze the spectroscopy of hidden-charm pentaquark states, motivated by recent discoveries at the LHCb collaboration. Using the SU(3) flavor representation, pentaquarks having $J^P = 5/2^-$…
For purely leptonic decays of pseudoscalar mesons, the decay rates are related to the product of the relevant weak interaction-based CKM matrix element of the constituent quarks on the one hand, and the strong interaction parameter, the…
The SU(3) octet states with baryon number B = 2, hexaquark dibaryons, are considered. Decay coupling constants sum rules for dibaryon octet into two ordinary baryon octets with ?$\lambda_8$ first order SU(3) symmetry breaking are given. An…
In this paper, axion models supplemented by leptoquarks and diquarks are systematically analyzed. Turning on some couplings to and among these latter states permits to unify the Peccei-Quinn symmetry with baryon (B) and lepton (L) numbers,…
By comparing SU(3)-breaking scales of linear mass formulae, it is shown that the lowest vector, axial-vector, and scalar mesons all have a $\bar{q}q$ configuration, while the ground-state octet and decuplet baryons are $qqq$. Also, the…
We discuss the decays X^* -> Xe^+e^- (``Dalitz decays'') of excited heavy mesons into their ground states and an electron-positron pair. We argue that the measurement of the invariant mass spectrum of the lepton pair gives clear indication…
We evaluate the widths for the strong decays $\Sigma_c\to\Lambda_c \pi$, $\Sigma_c^*\to\Lambda_c \pi$ and $\Xi_c^{*}\to\Xi_c \pi$. The calculations have been done within a nonrelativistic constituent quark model with wave functions that…
Starting from a consistent SU(6) extension of the Weinberg-Tomozawa (WT) meson-baryon chiral Lagrangian (Phys. Rev. D74 (2006) 034025), we study the s-wave meson-baryon resonances in the strangeness S=-3 and negative parity sector. Those…
The calculation of the partial width of the rare t-quark decay into Upsilon-meson, W-boson and b-quark (t -> \Upsilon W b) is presented. The branching ratio equals Br(t -> Upsilon W b) = 1.3 * 10^{-5} that make possible searches for this…
The known ratio of the branching fractions for D_s^* --> D_s pi^0 and D_s^* --> D_s gamma may be used to extract the coupling of eta mesons to strange quarks once the value of the pi^0-eta mixing angle is known. This requires that realistic…