Hidden charm dynamically generated resonances and the e+e−→J/ψDDˉe^+e^-\to J/\psi D \bar D, J/ψDDˉ∗J/\psi D\bar D^* reactions

We analyze two recent reactions of Belle, producing $D\bar D$ and $D\bar D^*$ states that have an enhancement of the invariant $D\bar D$, $D\bar D^*$ mass distribution close to threshold, from the point of view that they might be indicative of the existence of a hidden charm scalar and an axial vector meson states below $D\bar D$ or $D\bar D^*$ thresholds, respectively. We conclude that the data is compatible with the existing prediction of a hidden charm scalar meson with mass around 3700 MeV, though other possibilities cannot be discarded. The peak seen in the $D\bar D^*$ spectrum above threshold is, however, unlikely to be due to a threshold enhancement produced by the presence, below threshold, of the hidden charm axial vector meson X(3872).Comment: 5 pages, 5 figures, 2 table

Isospin breaking effects in the X(3872) resonance

In this paper we study the effects of isospin breaking in the dynamical generation of the X(3872) state. We also calculate the ratio of the branching fractions of the $X$ decaying into $J/\psi$ with two and three pions, which has been measured experimentally to be close to unity. Together with the X(3872), of positive C-parity, we predict the existence of a negative C-parity state and we comment on which decay channel is more promising to observe this state.Comment: 10 pages, 6 figures, study on the line shape of the X(3872) adde

Charm and Hidden Charm Scalar Resonances in Nuclear Matter

We study the properties of the scalar charm resonances $D_{s0}(2317)$ and $D_0(2400)$, and the theoretical hidden charm state X(3700) in nuclear matter. We find that for the $D_{s0}(2317)$ and X(3700) resonances, with negligible and small width at zero density, respectively, the width becomes about $100 {\rm MeV}$ and $200 {\rm MeV}$ at normal nuclear matter density, accordingly. For $D_0(2400)$ the change in width is relatively less important. We discuss the origin of this new width and trace it to reactions occurring in the nucleus. We also propose a possible experimental test for those modifications in nuclear matter, which will bring valuable information on the nature of those scalar resonances and the interaction of $D$ mesons with nucleons.Comment: 3 pages, 3 figures, to appear in the proceedings of the International Conference on Particles And Nuclei (PANIC08), Eilat, Israel, November 9-14, 200

The radiative decay of ψ(3770)\psi(3770) into the predicted scalar state X(3700)

We calculate the radiative decay width of the $\psi(3770)$ into the dynamically generated scalar resonance X(3700) which is predicted in a previous paper. The results show that it is possible that the upgraded BEPC-II facility will generate enough statistics in order to observe this decay and thus confirm the existence of the X(3700).Comment: 5 pages, 1 figur

Couplings in coupled channels versus wave functions: application to the X(3872) resonance

We perform an analytical study of the scattering matrix and bound states in problems with many physical coupled channels. We establish the relationship of the couplings of the states to the different channels, obtained from the residues of the scattering matrix at the poles, with the wave functions for the different channels. The couplings basically reflect the value of the wave functions around the origin in coordinate space. In the concrete case of the X(3872) resonance, understood as a bound state of \ddn and \ddc (and $c.c.$), with the \ddn loosely bound, we find that the couplings to the two channels are essentially equal leading to a state of good isospin I=0 character. This is in spite of having a probability for finding the \ddn state much larger than for \ddc since the loosely bound channel extends further in space. The analytical results, obtained with exact solutions of the Schr\"odinger equation for the wave functions, can be useful in general to interpret results found numerically in the study of problems with unitary coupled channels methods.Comment: 14 pages, 4 figure

Isospin breaking effects in the dynamical generation of the X(3872)

We have studied isospin breaking effects in the X(3872) resonance and found a natural explanation for the branching fraction of the X decaying to $J/\psi$ with two and three pions being close to unit. Within our framework the X(3872) is a dynamically generated resonance in coupled channels. We also study the relationship between the couplings of the resonance to the coupled channels with its wave function, which further helps us to understand the isospin structure of the resonance.Comment: 5 pages, 1 figure. To appear in the Proceedings of XIII International Conference on Hadron Spectroscopy, November 29 - December 4, 2009, Florida State Universit

Radiative decays of dynamically generated charmed baryons

In this work we study the radiative decay of dynamically generated J^P=\oh^- charm baryons into the ground state J^P=\oh^+ baryons. Since different theoretical interpretations of these baryonic resonances, and in particular of the $\Lambda_c(2595)$, give different predictions, a precise experimental measurement of these decays would be an important step for understanding their nature.Comment: 10 pages, 1 figur

Charm at FAIR

Charmed mesons in hot and dense matter are studied within a self-consistent coupled-channel approach for the experimental conditions of density and temperature expected at the CBM experiment at FAIR/GSI. The $D$ meson spectral function broadens with increasing density with an extended tail towards lower energies due to $\Lambda_c(2593) N^{-1}$ and $\Sigma_c(2800) N^{-1}$ excitations. The in-medium $\bar D$ meson mass increases with density. We also discuss the consequences for the renormalized properties in nuclear matter of the charm scalar $D_{s0}(2317)$ and D(2400), and the predicted hidden charm X(3700) resonances at FAIR energies.Comment: 6 pages, 3 figures, to appear in the proceedings of ExcitedQCD 09, Zakopane, Poland, 8-14 February 200