Fully heavy pentaquark states from QCD sum rules
Zheng-Lei Jing, Jian-Rong Zhang
TL;DR
This work uses QCD sum rules to predict the masses of fully heavy pentaquarks with quark content $QQQQ\bar{Q}$, employing three baryon-meson form interpolating currents. The authors derive two-point sum rules with perturbative and gluon-condensate contributions up to $\langle g^3 G^3\rangle$, and compute the spectra for all-charm $cccc\bar{c}$ and all-bottom $bbbb\bar{b}$ states. Their results place the three $cccc\bar{c}$ masses around $7.76-7.81$ GeV and the three $bbbb\bar{b}$ masses around $22.27-22.37$ GeV, with uncertainties, and indicate these states lie below corresponding baryon–meson thresholds, suggesting loosely bound configurations. The paper discusses model comparisons, notes generally lower $J^{P}=\frac{3}{2}^-}$ predictions than some models, and proposes experimental search channels in specific invariant-mass spectra, underscoring the potential discovery prospects for these exotic multi-quark states.
Abstract
In this work, we systematically investigate the mass spectra of fully heavy pentaquark states $QQQQ\bar{Q}$ within the framework of QCD sum rules. Employing three configurations of interpolating currents, we obtain the following mass predictions: for the $cccc\bar{c}$ states, the masses are determined to be $7.79^{+0.18}_{-0.17}$ GeV, $7.76^{+0.23}_{-0.18}$ Gev, $7.81^{+0.17}_{-0.18}$ GeV; while for the $bbbb\bar{b}$ states, the corresponding masses are calculated as $22.35^{+0.19}_{-0.19}$ GeV, $22.27^{+0.22}_{-0.22}$ GeV, $22.37^{+0.18}_{-0.20}$ GeV, respectively.