The charged $Z_c$ and $Z_b$ structures in a constituent quark model approach

The nature of the recently discovered Z_cZc and Z_bZb structures is intriguing. Their charge forces its minimal quark content to be Q\bar Q q\bar qQQ‾qq‾ (where Q=\{c,b\}Q={c,b} and q=\{u,d\}q={u,d}). In this work we perform a molecular coupled-channels calculation of the I^G(J^{PC})=1^+(1^{+-})IG(JPC)=1+(1+−) charm and bottom sectors in the framework of a constituent quark model which satisfactorily describes a wide range of properties of (non-)conventional hadrons containing heavy quarks. All the relevant channels are included for each sector, i.e.: The D^{(\ast)}\bar D^{\ast}+h.c.D(*)D‾*+h.c., \pi J/\psiπJ/ψ and \rho\eta_cρηc channels for the Z_cZc and B^{(\ast)}B^{\ast}B(*)B* and \Upsilon(nS)\piΥ(nS)π (n=1,2,3n=1,2,3) channels for the Z_bZb analysis. Possible structures of these resonances will be discussed.

Some proposed fixed target experiments with the LHC beams

The physics opportunities offered by using the multi-TeV LHC beams for a fixed target experiment have been widely discussed in recent years. This mode is convenient to investigate rare processes of particle production and polarization phenomena because the expected luminosity exceeds the luminosity of the collider. The main physical goals of these experiments are: i) investigations of the large-x gluon, antiquark and heavy quark content in the nucleon and nucleus; ii) investigations of the dynamics and spin of quarks and gluons inside nucleus; iii) studies of the ion-ion collisions between SPS and RHIC energies towards large rapidities. With the LHC lead beam energy scan on a fixed target it would be possible to investigate the energy range up to 72 GeV to search for the critical point for the phase transition to the Quark Gluon Plasma (QGP).