Emergence of a complete heavy-quark spin symmetry multiplet; Seven molecular pentaquarks in light of the latest LHCb analysis
Liu, M.-Z.*; Pan, Y.-W.*; Peng, F.-Z.*; S
nchez-S
nchez, M.*; Geng, L.-S.*; Hosaka, Atsushi; Valderrama, M. P.*
A recent analysis by the LHCb Collaboration suggests the existence of three narrow pentaquarklike states-the
(4312),
(4440), and
(4457)-instead of just one in the previous analysis [the
(4450)]. The closeness of the
(4312) to the
threshold and the
(4440) and
(4457) to the
threshold suggests a molecular interpretation of these resonances. We show that these three pentaquarklike resonances can be naturally accommodated in a contact-range effective field theory description that incorporates heavy-quark spin symmetry. This description leads to the prediction of all the seven possible
-wave heavy antimeson-baryon molecules [that is, there should be four additional molecular pentaquarks in addition to the
(4312),
(4440), and
(4457)], providing the first example of a heavy-quark spin symmetry molecular multiplet that is complete. If this is confirmed, it will not only give us an impressive example of the application of heavy-quark symmetries and effective field theories in hadron physics, it will also uncover a clear and powerful ordering principle for the molecular spectrum, reminiscent of the SU(3)-flavor multiplets to which the light hadron spectrum conforms.