Peaks within peaks and the possible two-peak structure of the Pc(4457): The effective field theory perspective

摘要

The LHCb pentaquarks—the P c ( 4312 ) , P c ( 4440 ) , and P c ( 4457 ) —have been theorized to be Σ c D ˉ and Σ c D ˉ * S-wave molecules. Here, we explore the possibility that two of these pentaquarks—the P c ( 4440 ) and P c ( 4457 ) —contain in addition a Λ c ( 2595 ) D ˉ component in the P-wave. We will analyze the effects of this extra channel within two effective field theories: the first one will be a standard contact-range effective field theory, and the second one will include the nondiagonal pion dynamics connecting the Σ c D ˉ * and Λ c ( 2595 ) D ˉ channels, which happens to be unusually long ranged. The impact of the coupled-channel dynamics between the Σ c D ˉ * and Λ c ( 2595 ) D ˉ components is modest at best for the P c ( 4440 ) and P c ( 4457 ) , which will remain predominantly Σ c D ˉ * molecules. However, if the quantum numbers of the P c ( 4457 ) are J P = 1 2 ? , the coupled-channel dynamics is likely to induce the binding of a Λ ( 2595 ) D ˉ S-wave molecule (coupled to Σ c D ˉ * in the P-wave) with J P = 1 2 + and a mass similar to the P c ( 4457 ) . If this is the case, the P c ( 4457 ) could actually be a double peak containing two different pentaquark states.