2019/04/30 by Xiaoyun Wang, Xiao-Yun Wang, Xurong Chen +2 · 1 citation
Physics and Astronomy · #Branching fraction #Energy (signal processing) #Hadron #High-Energy Particle Collisions Research #Nuclear physics #Particle physics #Particle physics theoretical and experimental studies #Pentaquark #Physics #Pomeron #Quantum Chromodynamics and Particle Interactions #Quantum mechanics #hep-ph #nucl-ex #nucl-th
paper · pdf · doi:10.1103/physrevd.99.114007
published as Phys. Rev. D 99, 114007 (2019) · 7 pages, 7 figures, version to be published in PRD
openalex created_date 2019/05/03 · arxiv created 2019/05/31 · openalex publication_date 2019/06/11 · arxiv updated 2019/06/13 · openalex updated_date 2026/08/05
Inspired by the observation of the pentaquark states Pc(4312), Pc(4440), and Pc(4457) at LHCb, photoproduction of these three Pc states via the interaction \ensuremathγp\ensuremath→J/\ensuremathψp is investigated in an effective Lagrangian approach. The t-channel Pomeron exchange diffractive process is considered as the main background for the J/\ensuremathψ photoproduction. The numerical results show that the theoretical cross section, which is calculated by assuming a branching ratio Br[Pc\ensuremath→J/\ensuremathψp]\ensuremath≃3%, is consistent with the existing experimental data of the \ensuremathγp\ensuremath→J/\ensuremathψp process. With such a branching ratio, if experimental precision reaches 0.1 nb within a bin of 100 MeV for photon energy, two peaks are expected to be obviously observed in the J/\ensuremathψ photoproduction. To observe the two-peak structure from Pc(4440) and Pc(4457), higher precision, about 0.1 nb/10 MeV, is required to distinguish two close pentaquarks. If the physical branching ratio is larger, the requirement of experimental precision will be reduced. The differential cross sections for reaction \ensuremathγp\ensuremath→J/\ensuremathψp are also present. It is found that the t-channel Pomeron exchange provides a sharp increase at extreme forward angles and gives a sizable contribution at most energy points, while the contributions from the s-channel Pc exchanges play important roles at threshold energies. The experimental measurement of the \ensuremathγp\ensuremath→J/\ensuremathψp process in the near-threshold energy region around E_\ensuremathγ\ensuremath≃9.4--10.5 GeV is suggested and is accessible at CEBAF@JLab and COMPASS.