Quark-model search for compact $c\bar{c}uds$ pentaquark states

Abstract

A potential quark model is used to search for a $P_{c\bar{c}s}^0=(c\bar{c}uds{)}^0$, $J^P=1/2^{-}$ pentaquark state that has recently been observed experimentally by the LHCb collaboration at 4338.2 MeV, with a width of 7.0 MeV and high statistical significance $>15\sigma$. Our model Hamiltonian reproduces the masses of the low-lying charmed and strange hadrons. We use the Gaussian expansion method {to solve the} five-body Schrödinger equation. Employing the real scaling method {including} the relevant meson-baryon thresholds explicitly, sharp resonances are distinguished from the meson-baryon scattering states. We incorporate new color states of the color-octet meson and baryon configurations as well as the color-singlet configurations for the five-quark states. We find no $J^P=1/2^{-}$ resonance close to the observed state, and also none in the $J^P=3/2^{-}$ state. This increases the likelihood that $P_{c\bar{c}s}^0$ is a ${\Xi }_c\bar{D}$ hadronic molecule rather than a compact state.

10 pages, 6 figures

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