D. Gamermann

Dynamically generated open and hidden charm meson systems

We will study open and hidden charm scalar meson resonances within two different models. The first one is a direct application of a chiral Lagrangian already used to study flavor symmetry breaking in Skyrme models. In another approach to the problem a SU(4) symmetric Lagrangian is built and the symmetry is broken down to SU(3) by identifying currents where heavy mesons are exchanged and suppressing those. Unitarization in coupled channels leads to dynamical generation of resonances in both models, in particular, a new hidden charm resonance with mass 3.7 GeV is predicted. The small differences between these models and with previous works is discussed. We also perform an error analysis of the results, checking their stability and determining the uncertainties in masses and couplings of the heavy resonances.

Isospin breaking effects in the X(3872) resonance

We would like to thank discussions and encouragement from E. Swanson, E. Braaten, Y. Dong and E. Lyubovitskij. This work is partly supported by DGICYT contract number FIS2006-03438. We acknowledge the support of the European Community-Research Infrastructure Integrating Activity ”Study of Strongly Interacting Matter”(acronym HadronPhysics2, Grant Agreement n. 227431)under the Seventh Framework Programme of EU. Work supported in part by DFG (SFB/TR 16, ”Subnuclear Structure of Matter”).

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

We calculate the radiative decay width of the

Charm and hidden charm scalar mesons in the nuclear medium

\psi

The Y(4260) as a

(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) .

J/\psi K \bar{K}

We study the renormalization of the properties of low-lying charm and hidden charm scalar mesons in a nuclear medium, concretely of the Ds0(2317) and the theoretical hidden charm state X(3700) . We find that for the Ds0(2317) , with negligible width at zero density, the width becomes about 100MeV at normal nuclear-matter density, while in the case of the X(3700) the width becomes as large as 200MeV. We discuss the origin of this new width and trace it to reactions occurring in the nucleus, while offering a guideline for future experiments testing these changes. We also show how those medium modifications will bring valuable information on the nature of the scalar resonances and the mechanisms of the interaction of D mesons with nucleons and nuclei.

system

A study of the J/{psi}{pi}{pi} and J/{psi}KK systems, treating them as coupled channels, has been made by solving the Faddeev equations, with the purpose of investigating the possibility of generation of the J{sup PC}=1{sup --}, Y(4260) resonance due to the interaction between these three mesons. In order to do this, we start by solving the Bethe-Salpeter equation for the two pseudoscalar and for the vector-pseudocalar meson systems using the amplitudes obtained from the lowest order chiral Lagrangians as potentials. With the t- matrices generated from these potentials, which contain the poles of the {sigma}, f{sub 0}(980), and a{sub 0}(980) resonances for the pseudoscalar-pseudoscalar system and the pole of the X(3872), along with other new charmed resonant states, for the vector-pseudoscalar system, we solve the Faddeev equations. As a result, we get a peak around 4150 MeV with a width {approx}90 MeV when the invariant mass of the two pseudoscalars is close to that of the f{sub 0}(980)

Charm and Hidden Charm Scalar Resonances in Nuclear Matter

We study the properties of the scalar charm resonances Ds0(2317) and D0(2400), and the theoretical hidden charm state X(3700) in nuclear matter. We find that for the Ds0(2317) and X(3700) resonances, with negligible and small width at zero density, respectively, the width becomes about 100 MeV and 200 MeV at normal nuclear matter density, accordingly. For D0(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.

THE X(3872) AND OTHER X,Y,Z RESONANCES AS HIDDEN CHARM MESON-MESON MOLECULES

We report on some ideas concerning the nature of the X(3872) resonance and the need for approximately equal charged and neutral components of

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

D \bar{D}^* +cc