Exotic baryons as a hadronic molecule in the heavy quark region

Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Genova, via Dodecaneso 33, 16146 Genova, Italy

^* e-mail: yasuhiro.yamaguchi@ge.infn.it

Published online: 25 November 2016

Abstract

We study the hadronic molecules formed by the coupled-channel system of D̄^(*)Λ_c and D̄^(*)Σ_c^(*), inspired by the two hidden-charm pentaquark states observed by LHCb collaborations in 2015. In these molecules, the coupled channels of D̄^(*)Σ_c^(*) are important because the thresholds of these channels are approximately degenerated by the heavy quark spin symmetry. In addition, we consider the coupling to the D̄^(*)Λ_c channel whose thresholds are close to the D̄^(*)Σ_c^(*) thresholds, and the coupling to the state with ℓ ≠ 0 mixed by the tensor force. By solving the coupled-channel Schrödinger equations with the one meson exchange potentials, we study the hidden-charm hadronic molecules with I(J^P) = 1/2(3/2^±) and 1/2(5/2^±). We conclude that the J^P assignment of the observed pentaquarks is 3/2⁺ for P⁺_c (4380) and 5/2⁻ for P⁺_c (4450), which is agreement with the results of the LHCb analysis. In addition, we give predictions for other J^P = 3/2^± states.