We present a coupled channel unitary approach to obtain states dynamically generated from the meson baryon interaction with hidden charm, using constraints of heavy quark spin symmetry. We use as basis of states,DB,D * B states, with B baryon charmed states belonging to the 20 representations of SU(4) with J P = 1/2 + , 3/2 + . In addition we also include the η c N and J/ψN states. The inclusion of these coupled channels is demanded by heavy quark spin symmetry, since in the large m Q limit the D and D * states are degenerate and are obtained from each other by means of a spin rotation, under which QCD is invariant. The novelty in the work is that we use dynamics from the extrapolation of the local hidden gauge model to SU(4) and we show that this dynamics fully respects the constraints of heavy quark spin symmetry.With the full space of states demanded by the heavy quark spin symmetry and the dynamics of the local hidden gauge we look for states dynamically generated and find four basic states which are bound, corresponding toDΣ c ,DΣ * c ,D * Σ c andD * Σ * c , decaying mostly into η c N and J/ψN . All the states appear in isospin I = 1/2 and we find no bound states or resonances in I = 3/2. TheDΣ c state appears in J = 1/2, theDΣ * c in J = 3/2, theD * Σ c appears nearly degenerate in J = 1/2, 3/2 and theD * Σ * c appears nearly degenerate in J = 1/2, 3/2, 5/2, with the peculiarity that in J = 5/2 the state has zero width in the space of states chosen. All the states are bound with about 50 MeV with respect to the correspondingDB thresholds and the width, except for the J = 5/2 state, is also of the same order of magnitude.

In this paper we examine the interaction of DN and D * N states, together with their coupled channels, by using an extension of the local hidden gauge formalism from the light meson sector, which is based on heavy quark spin symmetry. The scheme is based on the use of the impulse approximation at the quark level, with the heavy quarks acting as spectators, which occurs for the dominant terms where there is the exchange of a light meson. The pion exchange and the WeinbergTomozawa interactions are generalized and with this dynamics we look for states generated from the interaction, with a unitary coupled channels approach that mixes the pseudoscalar-baryon and vector-baryon states. We find two states with nearly zero width which are associated to the Λ c (2595) and Λ c (2625). The lower state, with J P = 1/2 − , couples to DN and D * N , and the second one, with J P = 3/2 − , to D * N . In addition to these two Λ c states, we find four more states with I = 0, one of them nearly degenerate in two states of J = 1/2, 3/2. Furthermore we find three states in I = 1, two of them degenerate in J = 1/2, 3/2. * liangwh@gxnu.edu.cn 1 I. INTRODUCTIONIn dealing with hadronic states involving heavy quarks (charm or beauty) the heavy quark spin symmetry [1][2][3][4] plays an important role and serves as a guiding principle to proceed with calculations. Heavy quark spin symmetry (HQSS) has been applied to calculate baryon spectra in Refs. [5][6][7][8][9][10][11][12]. The basic idea behind these works is to use HQSS to reduce the freedom in the interaction, which is then written in terms of a few parameters which are adjusted to some experimental data. Then predictions on spectra of baryons with charm or beauty, or hidden charm and beauty are made. In Ref.[5] an SU(8) spin-flavor scheme is used, to account for the spin symmetry, in order to obtain the interaction, and a coupled channels unitary approach is implemented to obtain poles in the scattering matrices, which correspond to the baryon resonance states. In particular the Λ c (2595) state is obtained and shown to couple largely to the D * N channel. In Ref.[8] the SU(8) scheme is once again used, but with some symmetry breaking, to match with an extension of the WeinbergTomozawa interaction in SU(3). Among other resonances, the states Λ c (2595) (J P = 1/2 − ) and Λ c (2625) (J P = 3/2 − ) are obtained. Further steps on the relationship of the Weinberg-Tomozawa interaction and HQSS are given in Refs. [10,13], where it is shown that this interaction, which stems from the exchange of vector mesons in the local hidden gauge approach [14][15][16] (see also Ref.[17] for practical rules), fulfills the HQSS. Indeed, the dominant terms correspond to the exchange of light vectors (the exchange of heavy vectors is suppressed), the heavy quarks act as spectators and hence the interaction does not depend on them. HQSS is then automatically fulfilled. Another step forward in this direction was given in Ref. [18], where using the impulse approximation at the quark level, the Weinb...

We consider theD ðÃÞ Σ ðÃÞ c states, together with J=ψN and other coupled channels, and take an interaction consistent with heavy quark spin symmetry, with the dynamical input obtained from an extension of the local hidden gauge approach. By fitting only one parameter to the recent three pentaquark states reported by the LHCb Collaboration, we can reproduce the three of them in base to the mass and the width, providing for them the quantum numbers and approximate molecular structure as 1=2 −D Σ c , 1=2 −DÃ Σ c , and 3=2 − D Ã Σ c , and the isospin I ¼ 1=2. We find another state around 4374 MeV, of the 3=2 −D Σ Ã c structure, for which indications appear in the experimental spectrum. Two other near degenerate states of a 1=2 −DÃ Σ Ã c and 3=2 −DÃ Σ Ã c nature are also found around 4520 MeV, which although less clear, are not incompatible with the observed spectrum. In addition, a 5=2 −DÃ Σ Ã c state at the same energy appears, which however does not couple to J=ψp in an S wave, and hence, it is not expected to show up in the LHCb experiment.

No abstract

Using a coupled channel unitary approach, combining the heavy quark spin symmetry and the dynamics of the local hidden gauge, we investigate the meson-meson interaction with hidden beauty and obtain several new states. Both I = 0 and I = 1 states are analyzed and it is shown that in the I = 1 sector, the interactions are too weak to create any bound states within our framework. In total, we predict with confidence the existence of 6 bound states, and weakly bound 6 more possible states. The existence of these weakly bound states depend on the influence of the coupled channel effects.