firstname = "Francisco"
lastname = "Fernandez"
email = "fdz@usal.es"
affiliation = "IUFFyM Universidad de Salamanca"
city = "Salamanca"
country = "Espaņa"
visa = "yes"
passportname = "Fernandez Gonzalez Francisco"
birthday = "04-10-1949"
citizenship = "espaņola"
passportnumber = "BF049424"
passportissued = "18-03-2009"
passportexpire = "18-03-2019"
workplace = "University of Salamanca Professor"
workaddress = "Calle del parque s/n 37008 Salamanca Spain"
visadates = "from 30-09-2013  to  5-10-2013"
transfer = "yes"
talktitle = "Molecular Charmonium. A new spectroscopy?"
section = "A - Particle physics"
talkabstract = "\documentstyle[epsfig,11pt]{article}
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\TITLE{Molecular Charmonium. A new spectroscopy?}\\[3mm]
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\AUTHORS{\underline{F. Fern\'andez}$^1$, P. G. Ortega $^2$ and D. R. Entem $^1$}
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{\small \it 
\AFFILIATION {1}{Grupo de F\'isica Nuclear and IUFFyM, Universidad de Salamanca, E-37008 Salamanca, Spain}
\AFFILIATION {2}{CERN Geneve} 
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\centerline{Contact email: {\it fdz@usal.es}}

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In different charmonium sectors several resonances like the X(3872), X(3915), G(3900), etc, has been reported in the last time without a clear theoretical interpretation in terms of $c\bar c$ pairs. Even in the baryon spectrum,
resonances like the $\Lambda^+_c(2940)$ are a challenge for theoretical models.
In this work we propose a theoretical explanation for this kind of phenomena as molecular structures coupled or not to $q\bar q$ states.
We work in the framework of a coupled channel calculation
~\cite{Baru} generalized to include several
meson-antimeson channels, several $q\bar q$ states below and resonances above threshold.

The $q\bar q$ states are found solving the Schr\"odinger 
equation in the framework of the constituent quark model of Ref.~\cite{Vijande}. This model includes pion exchanges between quarks which is very important to describe the $D\bar D$ and $D p$ interaction
The meson-antimeson interaction is consistently obtained
using the Resonating Group Method with these wave functions
and interaction.
Finally we couple the $q\bar q$ states with the $q\bar q q\bar q$ states
using the microscopic $^3 P_0$ model. 

In this calculation the well known X(3872) resonance appears as a $DD^*$ molecule coupled to a $\chi_{c_1}(2P)$ $c\bar c$ state. The original $\chi_{c_1}(2P)$ acquires a significant $DD^*$ component and can be identified with the X(3940).
In the $0^{++}$ sector we include in the calculation the
$\chi_{c0}(2P)$ $c\bar c$ state and the $DD$, $J/\psi\omega$, $D_sD_s$ and
$J/\psi\phi$ meson-antimeson states. We find two states which can be identified with the $X(3915)$ and with the sometimes called $Y(3940)$.
In the $1^{--}$ sector we obtain one new molecular state that could be assigned to the $G(3940)$ with an important dressing of the well established $\psi(4040)$ and $\psi(4160)$. Physical consequences of this dressing are discussed.

Our results shows a new phenomenology in the charmonium spectrum which may constitute a challenge for more fundamental descriptions like ADS/CFT correspondence.

However these new structures not only appear in the charmonium spectrum  but can also occur in the baryon sector.

We have extended the calculation to $DN$ and $BN$ molecules. We have identified the $\Lambda_c(2940)^+$ baryon as a $J^P=\frac{3}{2}^-$ $D^*N$ molecule ~\cite{PLB}. We have study the decay channels $\Lambda_c(2940)^+\rightarrow D^0p$, $\Lambda_c(2940)^+\rightarrow D^+n$,
$\Lambda_c(2940)^+\rightarrow \Sigma_c^{++} \pi^-$, $\Lambda_c(2940)^+\rightarrow \Sigma_c^{+} \pi^0$ and
$\Lambda_c(2940)^+\rightarrow \Sigma_c^0 \pi^+$.
The  obtained widths of the $D^0p$ and $D^+n$ decay channels are of the order of the experimental data whereas
the contributions of the $\Sigma_c\pi$ channels are negligible. The predicted total width  agrees with experimental data .

Moreover we predict in the same model the existence of new resonances in the $BN$ $D\Delta$ and $B\Delta$ channels with a relatively small width which can be discovered at LHCb in the near future.

\begin{thebibliography}{99}

\bibitem{Baru} V. Baru {\it et al.},
Eur. Phys. J. A {\bf 44}, 93 (2010).
Phys. Rev. D {\bf 79}, 092001 (2009).  

\bibitem{Vijande} J. Vijande, F. Fern\'andez, and A. Valcarce,
J. Phys. G {\bf 31}, 481 (2005).

\bibitem{PLB} P: G. Ortega, D. R. Entem, F. Fern\'andez Phys. Lett B in Press and arXiv:1210.2633


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