Pentaquark Bound States and Regge Trajectories in QCD via Bethe Salpeter Formalism
We present a comprehensive calculation of pentaquark masses and Regge trajectories within the framework of the Godfrey-Isgur relativized quark model. The pentaquark is treated as a meson-baryon molecular system, and the bound state is solved using the Bethe-Salpeter equation with the effective meson-baryon interaction motivated by GI, including smearing, running coupling, and spin-spin interactions. Using the latest PDG data for the known Pc and Pcs states, we compute the ground state and first two radial excitations for four pentaquark candidates: Pc(4440), Pc(4457), Pcs(4338), and Pcs(4459). The calculated masses are in excellent agreement with experiment. We also construct radial Regge trajectories in the (n, M^2) plane. Within the three calculated radial levels, the trajectories are approximately linear, with slopes comparable to those reported for ordinary hadrons. These results are consistent with a common confinement-driven pattern, but do not establish its universality.