Abstract: We study theoretically the resonant structure of the double Cabibbo suppressed D+ -> K-K+K+ decay. We start from an elementary production diagram, considered subleading in previous approaches, which cannot produce a final K-K+ pair at the tree level but which we show to be able to provide the strength of the decay through final meson-meson state interaction. The different meson-meson elementary productions are related through SU(3), and the final rescattering is implemented from a suitable implementation of unitary extensions of chiral perturbation theory, which generate dynamically the scalar resonances1 f(0)(980) and a(0)(980). We obtain a good agreement with recent experimental data from the LHCb Collaboration with a minimal freedom in the fit and show the dominance of the a(0)(980) contribution close to the threshold of the K-K+ spectrum.

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 study the time evolution of the numbers of charm mesons after the kinetic freeze-out of the hadron gas produced by a central heavy-ion collision. The pi D* -> pi D* reaction rates have t-channel singularities that give contributions inversely proportional to the thermal width of the D. The ratio of the D0 and D+ production rates can differ significantly from those predicted using the measured D* branching fractions.

Abstract: We study the temperature and baryon density dependence of the masses of the lightest charmed baryons Lambda(c), Sigma(c) and Sigma(c)*. We also look at the effects of the temperature and baryon density on the binding energies of the Lambda N-c and Lambda(c)Lambda(c) systems. Baryon masses and baryon-baryon interactions are evaluated within a chiral constituent quark model. Medium effects are incorporated in those parameters of the model related to the dynamical breaking of chiral symmetry, which are the masses of the constituent quarks, the sigma and pi meson masses, and quark-meson couplings. We find that while the in-medium Lambda(c) mass decreases monotonically with temperature, those of Sigma(c) and Sigma(c)* have a nonmonotonic dependence. These features can be understood in terms of a simple group theory analysis regarding the one-gluon exchange interaction in those hadrons. The in-medium Lambda N-c and Lambda(c)Lambda(c) interactions are governed by a delicate balance involving a stronger attraction due to the decrease of the sigma meson mass, suppression of coupled-channel effects and lower thresholds, leading to shallow bound states with binding energies of a few MeV. The Lambda(c) baryon could possibly be bound to a large nucleus, in qualitative agreement with results based on relativistic mean field models or QCD sum rules. Ongoing experiments at RHIC or LHCb or the planned ones at FAIR and J-PARC may take advantage of the present results.

Abstract: We study the structure of the Lambda(c) (2595) and Lambda(c) (2625) resonances in the framework of an effective field theory consistent with heavy quark spin and chiral symmetries, which incorporates the interplay between Sigma(()(c)*() )pi – ND(*()) baryon-meson degrees of freedom (d.o.f.) and bare P-wave c (u) over bard quark-model states. We show that these two resonances are not heavy quark spin symmetry partners. The J(P) = 3/2(-) Lambda(c) (2625) should be viewed mostly as a dressed three-quark state, whose origin is determined by a bare state, predicted to lie very close to the mass of the resonance. The J(P) = 1/2(-) Lambda(c) (2595) seems to have, however, a predominant molecular structure. This is because it is either the result of the chiral Sigma(c)pi interaction, whose threshold is located much closer than the mass of the bare three-quark state, or because the light d.o.f. in its inner structure are coupled to the unnatural 0(-) quantum numbers. We show that both situations can occur depending on the renormalization procedure used. We find some additional states, but the classification of the spectrum in terms of heavy quark spin symmetry is difficult, despite having used interactions that respect this symmetry. This is because the bare quark-model state and the Sigma(c)pi threshold are located extraordinarily close to the Lambda(c) (2625) and Lambda(c) (2595), respectively, and hence they play totally different roles in each sector.