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arXiv · 1512.00426

Narrow Nucleon-$ψ(2S)$ Bound State and LHCb Pentaquarks

Michael I. Eides·Victor Yu. Petrov·Maxim V. Polyakov
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Abstract

We interpret the newly discovered pentaquark $P_c(4450)$ as a bound state of charmonium $ψ(2S)$ and the nucleon. The binding potential is due to charmonium-nucleon interaction that in the heavy quark approximation is proportional to the product of the charmonium chromoelectric polarizability and the nucleon energy-momentum distribution. We use the large $N_c$ expansion to estimate the quarkonium polarizability and calculate the nucleon properties in the framework of the mean-field picture of light baryons. Two almost degenerate states $J^P=(1/2)^-$ and $J^P=(3/2)^-$ are predicted at the position of the $P_c(4450)$ pentaquark. We find that the nucleon-$ψ(2S)$ bound state has a naturally narrow width in the range of tens of MeV. The unitary multiplet partners of the $P_c(4450)$ pentaquark and the generalization to $b \bar b$-nucleon pentaquark bound states are discussed.

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Michael I. Eides, Victor Yu. Petrov, Maxim V. Polyakov. 2015-12-01. Narrow Nucleon-$ψ(2S)$ Bound State and LHCb Pentaquarks. https://doi.org/10.1103/physrevd.93.054039

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