Emergence of a Complete Heavy-Quark Spin Symmetry Multiplet: Seven Molecular Pentaquarks in Light of the Latest LHCb Analysis

Abstract

A recent analysis by the LHCb collaboration suggests the existence of three narrow pentaquark-like states -the P c (4312), P c (4440) and P c (4457) -instead of just one in the previous analysis (the P c (4450)). The closeness of the P c (4312) to theDΣ c threshold and the P c (4440)/P c (4457) to theD * Σ c one suggests a molecular interpretation of these resonances. We show that these three pentaquark-like 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 S-wave heavy antimeson-baryon molecules (that is, there should be four additional molecular pentaquarks in addition to the P c (4312), P c (4440) and P c (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.

Hidden-charm and hidden-bottom molecular pentaquarks in chiral effective field theory

“…After the above discussions, one may wonder whether it is possible to reproduce the three The J P quantum numbers of the P c (4312), P c (4440) and P c (4457) are not determined yet [10]. The theoretically favored J P for P c (4440) and P c (4457) in this paper and some previous works [11][12][13][14][15] The result of interchanging the spin assignment of P c (4440) and P c (4457) is given in figure 12(b). Marvelously, the result is comparable with the one in figure 8(b), i.e., it seems this assignment can well describe the experimental data, likewise.…”

“…In the April of this year, the LHCb collaboration reported the observation of the three pentaquark states P c (4312), P c (4440) and P c (4457) [10]. They were subsequently interpreted as the molecular states by many theoretical works [11][12][13][14][15] due to the proximities to the Σ cD and Σ cD * thresholds. In this paper, we have systematically investigated the interactions between the charmed baryons Σ ( * ) c and anticharmed mesonsD ( * ) in the framework of chiral perturbation theory.…”

Doubly charmed pentaquarks

“…The top panel of [3,4,6,19,22]; moreover, its 5-quark configuration is identified with a molecular state of Σ cD with mass and width 4311.9 ± 0.7 +6.8 −0.6 MeV and 9.8 ± 2.7 +3.7 is found in these channels; however, a loosely bound one of Σ c D * with a binding energy of E = −1 MeV could be obtained, as shown in Table VII. For the possible bound state of Σ c D * (4461), hidden-color channel helps a little in forming the baryon-meson molecular state.…”

“…A common one is the baryonmeson molecular picture, i.e. Σ cD ( * ) states described within different kind of formalisms such as effective field theories [3,4], heavy quark spin symmetry approach [5,6], phenomenological potential models [7][8][9][10][11][12][13], heavy hadron chiral perturbation theory [14], and QCD sum rules [15,16]. The P c (4312) + and P c (4457) + signals have been studied independently in Refs.…”

“…Bottom panel: Enlarged top panel, with real values of energy ranging from 4.35 GeV to 4.46 GeV.charm P + c (4457) state. The later one is explained as Σ cD * molecular state with quantum numbers IJ P = 1[3,4,6,19,22], and its experimental mass and width is 4457.3 ± 0.6 +4.MeV and 6.4 ± 2.0 +5.MeV, respectively. The nature of our candidate Σ * c D(4449) molecular state is deserved to be investigated in future experimental facilities.…”