Abstract
On March 26th, 2019, at the Rencontres de Moriond QCD conference, the LHCb Collaboration reported the observation of three new pentaquarks, namely $P_c(4312)$, $P_c(4440)$ and $P_c(4457)$, which are consistent with the loosely bound molecular hidden-charm pentaquark states composed of an S-wave charmed baryon $\Sigma_c$ and an S-wave anti-charmed meson ($\bar{D}, \bar{D}^*$). In this work, we present a direct calculation by the one-boson-exchange (OBE) model and demonstrate explicitly that the $P_c(4312)$, $P_c(4440)$ and $P_c(4457)$ do correspond to the loosely bound $\Sigma_c\bar{D}$ with $(I=1/2,J^P=1/2^-)$, $\Sigma_c\bar{D}^*$ with $(I=1/2,J^P=1/2^-)$ and $\Sigma_c\bar{D}^*$ with $(I=1/2,J^P=3/2^-)$, respectively.
Highlights
Finding the multiquark matter is an extremely important issue of hadron physics, which is full of challenge and opportunity for theorists and for experimentalists
On 26 March 2019, at the Rencontres de Moriond QCD conference, the LHCb Collaboration reported the observation of three new pentaquarks, namely Pcð4312Þ, Pcð4440Þ, and Pcð4457Þ, which are consistent with the loosely bound molecular hidden-charm pentaquark states composed of an S-wave charmed baryon Σc and an S-wave anticharmed meson (D, D Ã)
We present a direct calculation by the oneboson-exchange model and demonstrate explicitly that the Pcð4312Þ, Pcð4440Þ, and Pcð4457Þ do correspond to the loosely bound ΣcDwith (I 1⁄4 1=2, JP 1⁄4 1=2−), ΣcD Ã with (I 1⁄4 1=2, JP 1⁄4 1=2−), and ΣcD Ã with (I 1⁄4 1=2, JP 1⁄4 3=2−), respectively
Summary
Finding the multiquark matter is an extremely important issue of hadron physics, which is full of challenge and opportunity for theorists and for experimentalists. In the past 16 years, a series of observations of the charmoniumlike XYZ states and two Pc states have inspired extensive investigations of the hidden-charm tetraquarks and pentaquarks, which enlarge our knowledge of the multiquark matter (see review articles [1–3] for more details). In 2015, LHCb announced the observation of two hidden-charm pentaquarks Pcð4380Þ and Pcð4450Þ in the J=ψp invariant mass spectrum of Λb → J=ψKp [9]. This observation had stimulated extensive discussions on decoding their inner structures based on different configurations, which include the loosely bound molecular baryon-meson state [10–12] and tightly bound pentaquark state [13–16]. The LHCb updated analysis further indicates that the Pcð4450Þ reported previously by LHCb [9] contains two narrow subpeaks, Pcð4440Þ and Pcð4457Þ, which have 5.4σ significance By borrowing the experience of studying nuclear force, the one-boson-exchange (OBE) model was developed to
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