Abstract
In a chromomagnetic model, we analyse the properties of the newly observed $P_c(4457)^+$, $P_c(4440)^+$, and $P_c(4312)^+$ states. We estimate the masses of the $(uud)_{8_c}(c\bar{c})_{8_c}$ and $(uds)_{8_c}(c\bar{c})_{8_c}$ pentaquark states by considering the isospin breaking effects. Their values are determined by calculating mass distances from the $\Sigma_c^{++}D^-$ and $\Xi_c^{\prime+}D^-$ thresholds, respectively. It is found that the isospin breaking effects on the spectrum are small. From the uncertainty consideration and the rearrangement decay properties in a simple model, we find that it is possible to assign the $P_c(4457)^+$, $P_c(4440)^+$, and $P_c(4312)^+$ as $J^P=3/2^-$, $1/2^-$, and $3/2^-$ pentaquark states, respectively. The assignment in the molecule picture can be different, in particular for the $P_c(4312)^+$. The information from open-charm channels, e.g. ${\cal B}[P_c\to\Sigma_c^{++}D^-]/{\cal B}[P_c\to J/\psi p]$, will play an important role in distinguishing the inner structures of the $P_c$ states. Discussions and predictions based on the calculations are also given.
Highlights
The LHCb Collaboration observed two pentaquarklike Pcð4380Þ and Pcð4450Þ states in the invariant mass distribution of J=ψp in the Λ0b decay in 2015 [1,2,3]
There are pioneering works about hidden-charm type pentaquarks before the observation [4,5,6,7,8] and lots of heated discussions on their structures motivated by this observation. These two Pc states have been widely discussed in the ΣcD Ã, ΣÃcD, or ΣÃcD Ã molecule picture, diquark-diquark-antiquark picture, diquark-triquark picture, compact pentaquark picture, and nonresonance picture
The previously observed Pcð4450Þ consists of the latter two states. These three newly observed Pc states are certainly helpful to deepen our understandings about the nature of strong interactions
Summary
The LHCb Collaboration observed two pentaquarklike Pcð4380Þ and Pcð4450Þ states in the invariant mass distribution of J=ψp in the Λ0b decay in 2015 [1,2,3]. These three newly observed Pc states are certainly helpful to deepen our understandings about the nature of strong interactions Because these states are just below the ΣcDor ΣcD Ã threshold with narrow decay widths, a typical feature expected for molecules and their structures in the molecule picture have been discussed through various. We would like to investigate another possibility, namely, they are compact pentaquark states composed of colored cc. The mass of the lowest uudccstate was found to be consistent with the prediction in the molecule picture given in Ref. The decay properties of pentaquarks should be different and the relevant studies are helpful to distinguish their structures. In understanding the nature of Pcð4380Þ and Pcð4450Þ and in predicting other pentaquark states, investigations in this compact picture were performed in Refs.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
