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      Mass spectrum of the hidden-charm pentaquarks in the compact diquark model

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          Abstract

          The LHCb collaboration have recently updated their analysis of the resonant \(J/\psi p\) mass spectrum in the decay \(\Lambda_b^0 \to J/\psi p K^-\), making use of their combined Run 1 and Run 2 data. In the updated analysis, three narrow states, \(P_c (4440)^+\), \(P_c (4457)^+\),and \(P_c (4312)^+\), are observed. The spin-parity assignments of these states are not yet known. We interpret these narrow resonances as compact hidden-charm diquark-diquark-antiquark pentaquarks. Using an effective Hamiltonian, based on constituent quarks and diquarks, we calculate the pentaquark mass spectrum for the complete \(SU (3)_F\) lowest \(S\)- and \(P\)-wave multiplets, taking into account dominant spin-spin, spin-orbit, orbital and tensor interactions. The resulting spectrum is very rich and we work out the quark flavor compositions, masses, and \(J^P\) quantum numbers of the pentaquarks. However, heavy quark symmetry restricts the observable states in \(\Lambda_b\)-baryon, as well as in the decays of the other weakly-decaying \(b\)-baryons, \(\Xi_b\) and \(\Omega_b\). In addition, some of the pentaquark states are estimated to lie below the \(J/\psi p\) threshold in \(\Lambda_b\)-decays (and corresponding thresholds in \(\Xi_b\)- and \(\Omega_b\)-decays). They decay via \(c \bar c\) annihilation into light hadrons or a dilepton pair, and are expected to be narrower than the \(P_c\)-states observed. We anticipate their discovery, as well as of the other pentaquark states present in the spectrum at the LHC, and in the long-term future at a Tera-\(Z\) factory.

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          \(Z(4430)\)and a new paradigm for spin interactions in tetraquarks

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            Baryons with two heavy quarks: Masses, production, decays, and detection

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              Study of \(P_c(4457)\), \(P_c(4440)\), and \(P_c(4312)\) in a quasipotential Bethe–Salpeter equation approach

              Jun. He (2019)
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                Author and article information

                Journal
                15 July 2019
                Article
                1907.06507
                61e7cb1f-1862-4aae-bf7b-a7bca36c381c

                http://creativecommons.org/licenses/by/4.0/

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                Custom metadata
                DESY 19-052
                65 pages, 1 figure, 16 tables, to be submitted to JHEP
                hep-ph hep-ex hep-lat

                High energy & Particle physics
                High energy & Particle physics

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