Abstract
We discuss the mass splittings for the S-wave triply heavy pentaquark states with the QQQqbar{q}(Q=b,c;q=u,d,s) configuration which is a mirror structure of Qbar{Q}qqq. The latter configuration is related with the nature of P_c(4380) observed by the LHCb Collaboration. The considered pentaquark masses are estimated with a simple method. One finds that such states are probably not narrow even if they do exist. This leaves room for molecule interpretation for a state around the low-lying threshold of a doubly heavy baryon and a heavy-light meson, e.g. Xi _{cc}D, if it were observed. As a by product, we conjecture that upper limits for the masses of the conventional triply heavy baryons can be determined by the masses of the conventional doubly heavy baryons.
Highlights
The LHCb Collaboration confirmed the cc baryon [1] which was predicted in the quark model (QM) decades ago [2] and first measured by the SELEX Collaboration in 2002 [3]
The Pc(4380) and Pc(4450) states observed in the J/ψ N channel by the LHCb Collaboration [17] can be interpreted as pentaquark states since their high masses are not natural for conventional 3q baryons [18]
In the study of the Q Q Q Qsystems [33], we checked the effective interaction between two heavy quarks in the mixing case by varying the effective coupling strengths, through which we may roughly guess whether the tetraquark states are stable or not
Summary
The LHCb Collaboration confirmed the cc baryon [1] which was predicted in the quark model (QM) decades ago [2] and first measured by the SELEX Collaboration in 2002 [3]. The most exciting thing in hadron physics is that more and more unexpected hadrons are detected [5,6,7,8,9,10,11,12,13,14,15,16] and hadrons beyond the conventional quark model should exist This indicates that we may identify the existence of multiquark states before the confirmation of all the QM states. The Pc(4380) and Pc(4450) states observed in the J/ψ N channel by the LHCb Collaboration [17] can be interpreted as pentaquark states since their high masses are not natural for conventional 3q baryons [18]. One expects that conventional triply heavy baryons rather than pentaquarks would be found experimentally first
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