Abstract: We investigate the production of exotic tetraquarks, QQ (q) over bar (q) over bar T-QQ (Q = c or b and q = u or d), in relativistic heavy-ion collisions using the quark coalescence model. The T-QQ yield is given by the overlap of the density matrix of the constituents in the emission source with the Wigner function of the produced tetraquark. The tetraquark wave function is obtained from exact solutions of the four-body problem using realistic constituent models. The production yields are typically one order of magnitude smaller than previous estimations based on simplified wave functions for the tetraquarks. We also evaluate the consequences of the partial restoration of chiral symmetry at the hadronization temperature on the coalescence probability. Such effects, in addition to increasing the stability of the tetraquarks, lead to an enhancement of the production yields, pointing towards an excellent discovery potential in forthcoming experiments. We discuss further consequences of our findings for the search of exotic tetraquarks in central Pb + Pb collisions at the LHC.

Abstract: The mass spectrum of pi(+) and rho(+) mesons in the presence of a static uniform magnetic field (B) over right arrow is studied within a two-flavor Nambu-Jona-Lasinio-like model. We improve previous calculations, taking into account the effect of Schwinger phases carried by quark propagators and using an expansion of meson fields in terms of the solutions of the corresponding equations of motion for nonzero B. It is shown that the meson polarization functions are diagonal in this basis. Our numerical results for the rho(+) meson spectrum are found to disfavor the existence of a meson condensate induced by the magnetic field. In the case of the pi(+) meson, pi-rho mixing effects are analyzed for the meson lowest-energy state. The predictions of the model are compared with available lattice QCD results.

Abstract: We study the weak decay Omega(-)(b) -> (Xi(+)(c) K-)pi(-), in view of the narrow Omega(c) states recently measured by the LHCb Collaboration and later confirmed by the Belle Collaboration. The Omega(c) (3050) and Omega(c) (3090) are described as meson-baryon molecular states, using an extension of the local hidden gauge approach in coupled channels. We investigate the Xi D, Xi(c)(K) over bar, and. Xi '(c) (K) over bar invariant mass distributions making predictions that could be confronted with future experiments, providing useful information that could help determine the quantum numbers and nature of these states.

Abstract: We have made a study of the J/psi -> eta'h(1), eta h(1) [with h(1) being /11(1170) and h(1)(1380)1 and P/psi ->pi(0)b(1) 171(1235)(0) assuming the axial vector mesons to be dynamically generated from the pseudoscalar-vectormeson interaction. We have taken the needed input from previous studies of the J/psi -> phi pi pi, omega pi pi reactions. We obtain fair agreement with experimental data and provide an explanation on why the recent experiment on J/psi -> eta'h(1)(1380), h(1)(1380) -> K*K-+(-) + c.c. observed in the K+K-pi(0) mode observes the peak of the h(1)(1380) at a higher energy than its nominal mass.

Abstract: Stimulated by the new experimental LHCb findings associated with the Omega(c) states, some of which we have described in a previous work as being dynamically generated through meson-baryon interaction, we have extended this approach to make predictions for new Xi(cc) molecular states in the C = 2, S = 0, and I = 1/2 sector. These states manifest themselves as poles in the solution of the Bethe-Salpeter equation in coupled channels. The kernels of this equation were obtained using general Lagrangians coming from the hidden local gauge symmetry or massive Yang-Mills theory, and the interactions are dominated by the exchange of light vector mesons. The extension of this approach to the heavy sector stems from the realization that the dominant interaction corresponds to having the heavy quarks as spectators, which implies the preservation of the heavy quark symmetry. As a result, we get several states: three states from the pseudoscalar meson-baryon interaction with J(P) = 1/2(-), and masses around 3840, 4080 and 4090 MeV, and two at 3920 and 4150 MeV for J(P) = 3/2(-). Furthermore, from the vector meson-baryon interaction we get three states degenerate with J(P) 1/2(-) and 3/2(-) from 4220 MeV to 4290 MeV, and two more states around 4280 and 4370 MeV, degenerate with J(P) = 1/2(-), 3/2(-), and 5/2(-).